Fix all the links to be relative for mdbook 2
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@ -94,7 +94,7 @@ and Michael I. Schwartzbach is an incredible resource!
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Check out the subtyping chapter from the
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Check out the subtyping chapter from the
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[Rust Nomicon](https://doc.rust-lang.org/nomicon/subtyping.html).
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[Rust Nomicon](https://doc.rust-lang.org/nomicon/subtyping.html).
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See the [variance](./variance.html) chapter of this guide for more info on how
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See the [variance](../variance.html) chapter of this guide for more info on how
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the type checker handles variance.
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the type checker handles variance.
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<a name="free-vs-bound"></a>
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<a name="free-vs-bound"></a>
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@ -29,16 +29,16 @@ Item | Kind | Short description | Chapter |
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`Ty<'tcx>` | struct | This is the internal representation of a type used for type checking | [Type checking] | [src/librustc/ty/mod.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty/type.Ty.html)
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`Ty<'tcx>` | struct | This is the internal representation of a type used for type checking | [Type checking] | [src/librustc/ty/mod.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty/type.Ty.html)
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`TyCtxt<'cx, 'tcx, 'tcx>` | type | The "typing context". This is the central data structure in the compiler. It is the context that you use to perform all manner of queries | [The `ty` modules] | [src/librustc/ty/context.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty/struct.TyCtxt.html)
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`TyCtxt<'cx, 'tcx, 'tcx>` | type | The "typing context". This is the central data structure in the compiler. It is the context that you use to perform all manner of queries | [The `ty` modules] | [src/librustc/ty/context.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty/struct.TyCtxt.html)
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[The HIR]: hir.html
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[The HIR]: ../hir.html
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[Identifiers in the HIR]: hir.html#hir-id
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[Identifiers in the HIR]: ../hir.html#hir-id
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[The parser]: the-parser.html
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[The parser]: ../the-parser.html
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[The Rustc Driver]: rustc-driver.html
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[The Rustc Driver]: ../rustc-driver.html
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[Type checking]: type-checking.html
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[Type checking]: ../type-checking.html
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[The `ty` modules]: ty.html
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[The `ty` modules]: ../ty.html
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[Rustdoc]: rustdoc.html
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[Rustdoc]: ../rustdoc.html
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[Emitting Diagnostics]: diag.html
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[Emitting Diagnostics]: ../diag.html
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[Macro expansion]: macro-expansion.html
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[Macro expansion]: ../macro-expansion.html
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[Name resolution]: name-resolution.html
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[Name resolution]: ../name-resolution.html
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[Parameter Environment]: param_env.html
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[Parameter Environment]: ../param_env.html
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[Trait Solving: Goals and Clauses]: traits/goals-and-clauses.html#domain-goals
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[Trait Solving: Goals and Clauses]: ../traits/goals-and-clauses.html#domain-goals
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[Trait Solving: Lowering impls]: traits/lowering-rules.html#lowering-impls
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[Trait Solving: Lowering impls]: ../traits/lowering-rules.html#lowering-impls
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@ -7,25 +7,25 @@ them better.
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Term | Meaning
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Term | Meaning
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------------------------|--------
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------------------------|--------
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AST | the abstract syntax tree produced by the syntax crate; reflects user syntax very closely.
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AST | the abstract syntax tree produced by the syntax crate; reflects user syntax very closely.
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binder | a "binder" is a place where a variable or type is declared; for example, the `<T>` is a binder for the generic type parameter `T` in `fn foo<T>(..)`, and \|`a`\|` ...` is a binder for the parameter `a`. See [the background chapter for more](./appendix/background.html#free-vs-bound)
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binder | a "binder" is a place where a variable or type is declared; for example, the `<T>` is a binder for the generic type parameter `T` in `fn foo<T>(..)`, and \|`a`\|` ...` is a binder for the parameter `a`. See [the background chapter for more](./background.html#free-vs-bound)
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bound variable | a "bound variable" is one that is declared within an expression/term. For example, the variable `a` is bound within the closure expession \|`a`\|` a * 2`. See [the background chapter for more](./appendix/background.html#free-vs-bound)
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bound variable | a "bound variable" is one that is declared within an expression/term. For example, the variable `a` is bound within the closure expession \|`a`\|` a * 2`. See [the background chapter for more](./background.html#free-vs-bound)
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codegen | the code to translate MIR into LLVM IR.
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codegen | the code to translate MIR into LLVM IR.
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codegen unit | when we produce LLVM IR, we group the Rust code into a number of codegen units. Each of these units is processed by LLVM independently from one another, enabling parallelism. They are also the unit of incremental re-use.
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codegen unit | when we produce LLVM IR, we group the Rust code into a number of codegen units. Each of these units is processed by LLVM independently from one another, enabling parallelism. They are also the unit of incremental re-use.
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completeness | completeness is a technical term in type theory. Completeness means that every type-safe program also type-checks. Having both soundness and completeness is very hard, and usually soundness is more important. (see "soundness").
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completeness | completeness is a technical term in type theory. Completeness means that every type-safe program also type-checks. Having both soundness and completeness is very hard, and usually soundness is more important. (see "soundness").
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control-flow graph | a representation of the control-flow of a program; see [the background chapter for more](./appendix/background.html#cfg)
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control-flow graph | a representation of the control-flow of a program; see [the background chapter for more](./background.html#cfg)
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CTFE | Compile-Time Function Evaluation. This is the ability of the compiler to evaluate `const fn`s at compile time. This is part of the compiler's constant evaluation system. ([see more](./const-eval.html))
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CTFE | Compile-Time Function Evaluation. This is the ability of the compiler to evaluate `const fn`s at compile time. This is part of the compiler's constant evaluation system. ([see more](../const-eval.html))
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cx | we tend to use "cx" as an abbreviation for context. See also `tcx`, `infcx`, etc.
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cx | we tend to use "cx" as an abbreviation for context. See also `tcx`, `infcx`, etc.
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DAG | a directed acyclic graph is used during compilation to keep track of dependencies between queries. ([see more](incremental-compilation.html))
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DAG | a directed acyclic graph is used during compilation to keep track of dependencies between queries. ([see more](../incremental-compilation.html))
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data-flow analysis | a static analysis that figures out what properties are true at each point in the control-flow of a program; see [the background chapter for more](./appendix/background.html#dataflow)
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data-flow analysis | a static analysis that figures out what properties are true at each point in the control-flow of a program; see [the background chapter for more](./background.html#dataflow)
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DefId | an index identifying a definition (see `librustc/hir/def_id.rs`). Uniquely identifies a `DefPath`.
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DefId | an index identifying a definition (see `librustc/hir/def_id.rs`). Uniquely identifies a `DefPath`.
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Double pointer | a pointer with additional metadata. See "fat pointer" for more.
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Double pointer | a pointer with additional metadata. See "fat pointer" for more.
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DST | Dynamically-Sized Type. A type for which the compiler cannot statically know the size in memory (e.g. `str` or `[u8]`). Such types don't implement `Sized` and cannot be allocated on the stack. They can only occur as the last field in a struct. They can only be used behind a pointer (e.g. `&str` or `&[u8]`).
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DST | Dynamically-Sized Type. A type for which the compiler cannot statically know the size in memory (e.g. `str` or `[u8]`). Such types don't implement `Sized` and cannot be allocated on the stack. They can only occur as the last field in a struct. They can only be used behind a pointer (e.g. `&str` or `&[u8]`).
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empty type | see "uninhabited type".
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empty type | see "uninhabited type".
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Fat pointer | a two word value carrying the address of some value, along with some further information necessary to put the value to use. Rust includes two kinds of "fat pointers": references to slices, and trait objects. A reference to a slice carries the starting address of the slice and its length. A trait object carries a value's address and a pointer to the trait's implementation appropriate to that value. "Fat pointers" are also known as "wide pointers", and "double pointers".
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Fat pointer | a two word value carrying the address of some value, along with some further information necessary to put the value to use. Rust includes two kinds of "fat pointers": references to slices, and trait objects. A reference to a slice carries the starting address of the slice and its length. A trait object carries a value's address and a pointer to the trait's implementation appropriate to that value. "Fat pointers" are also known as "wide pointers", and "double pointers".
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free variable | a "free variable" is one that is not bound within an expression or term; see [the background chapter for more](./appendix/background.html#free-vs-bound)
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free variable | a "free variable" is one that is not bound within an expression or term; see [the background chapter for more](./background.html#free-vs-bound)
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'gcx | the lifetime of the global arena ([see more](ty.html))
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'gcx | the lifetime of the global arena ([see more](../ty.html))
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generics | the set of generic type parameters defined on a type or item
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generics | the set of generic type parameters defined on a type or item
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HIR | the High-level IR, created by lowering and desugaring the AST ([see more](hir.html))
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HIR | the High-level IR, created by lowering and desugaring the AST ([see more](../hir.html))
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HirId | identifies a particular node in the HIR by combining a def-id with an "intra-definition offset".
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HirId | identifies a particular node in the HIR by combining a def-id with an "intra-definition offset".
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HIR Map | The HIR map, accessible via tcx.hir, allows you to quickly navigate the HIR and convert between various forms of identifiers.
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HIR Map | The HIR map, accessible via tcx.hir, allows you to quickly navigate the HIR and convert between various forms of identifiers.
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ICE | internal compiler error. When the compiler crashes.
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ICE | internal compiler error. When the compiler crashes.
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@ -36,39 +36,39 @@ IR | Intermediate Representation. A general term in compil
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local crate | the crate currently being compiled.
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local crate | the crate currently being compiled.
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LTO | Link-Time Optimizations. A set of optimizations offered by LLVM that occur just before the final binary is linked. These include optimizations like removing functions that are never used in the final program, for example. _ThinLTO_ is a variant of LTO that aims to be a bit more scalable and efficient, but possibly sacrifices some optimizations. You may also read issues in the Rust repo about "FatLTO", which is the loving nickname given to non-Thin LTO. LLVM documentation: [here][lto] and [here][thinlto]
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LTO | Link-Time Optimizations. A set of optimizations offered by LLVM that occur just before the final binary is linked. These include optimizations like removing functions that are never used in the final program, for example. _ThinLTO_ is a variant of LTO that aims to be a bit more scalable and efficient, but possibly sacrifices some optimizations. You may also read issues in the Rust repo about "FatLTO", which is the loving nickname given to non-Thin LTO. LLVM documentation: [here][lto] and [here][thinlto]
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[LLVM] | (actually not an acronym :P) an open-source compiler backend. It accepts LLVM IR and outputs native binaries. Various languages (e.g. Rust) can then implement a compiler front-end that output LLVM IR and use LLVM to compile to all the platforms LLVM supports.
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[LLVM] | (actually not an acronym :P) an open-source compiler backend. It accepts LLVM IR and outputs native binaries. Various languages (e.g. Rust) can then implement a compiler front-end that output LLVM IR and use LLVM to compile to all the platforms LLVM supports.
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MIR | the Mid-level IR that is created after type-checking for use by borrowck and codegen ([see more](./mir/index.html))
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MIR | the Mid-level IR that is created after type-checking for use by borrowck and codegen ([see more](../mir/index.html))
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miri | an interpreter for MIR used for constant evaluation ([see more](./miri.html))
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miri | an interpreter for MIR used for constant evaluation ([see more](../miri.html))
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normalize | a general term for converting to a more canonical form, but in the case of rustc typically refers to [associated type normalization](./traits/associated-types.html#normalize)
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normalize | a general term for converting to a more canonical form, but in the case of rustc typically refers to [associated type normalization](../traits/associated-types.html#normalize)
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newtype | a "newtype" is a wrapper around some other type (e.g., `struct Foo(T)` is a "newtype" for `T`). This is commonly used in Rust to give a stronger type for indices.
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newtype | a "newtype" is a wrapper around some other type (e.g., `struct Foo(T)` is a "newtype" for `T`). This is commonly used in Rust to give a stronger type for indices.
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NLL | [non-lexical lifetimes](./borrow_check/region_inference.html), an extension to Rust's borrowing system to make it be based on the control-flow graph.
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NLL | [non-lexical lifetimes](../borrow_check/region_inference.html), an extension to Rust's borrowing system to make it be based on the control-flow graph.
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node-id or NodeId | an index identifying a particular node in the AST or HIR; gradually being phased out and replaced with `HirId`.
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node-id or NodeId | an index identifying a particular node in the AST or HIR; gradually being phased out and replaced with `HirId`.
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obligation | something that must be proven by the trait system ([see more](traits/resolution.html))
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obligation | something that must be proven by the trait system ([see more](../traits/resolution.html))
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projection | a general term for a "relative path", e.g. `x.f` is a "field projection", and `T::Item` is an ["associated type projection"](./traits/goals-and-clauses.html#trait-ref)
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projection | a general term for a "relative path", e.g. `x.f` is a "field projection", and `T::Item` is an ["associated type projection"](../traits/goals-and-clauses.html#trait-ref)
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promoted constants | constants extracted from a function and lifted to static scope; see [this section](./mir/index.html#promoted) for more details.
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promoted constants | constants extracted from a function and lifted to static scope; see [this section](../mir/index.html#promoted) for more details.
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provider | the function that executes a query ([see more](query.html))
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provider | the function that executes a query ([see more](../query.html))
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quantified | in math or logic, existential and universal quantification are used to ask questions like "is there any type T for which is true?" or "is this true for all types T?"; see [the background chapter for more](./appendix/background.html#quantified)
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quantified | in math or logic, existential and universal quantification are used to ask questions like "is there any type T for which is true?" or "is this true for all types T?"; see [the background chapter for more](./background.html#quantified)
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query | perhaps some sub-computation during compilation ([see more](query.html))
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query | perhaps some sub-computation during compilation ([see more](../query.html))
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region | another term for "lifetime" often used in the literature and in the borrow checker.
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region | another term for "lifetime" often used in the literature and in the borrow checker.
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rib | a data structure in the name resolver that keeps track of a single scope for names. ([see more](./name-resolution.html))
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rib | a data structure in the name resolver that keeps track of a single scope for names. ([see more](../name-resolution.html))
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sess | the compiler session, which stores global data used throughout compilation
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sess | the compiler session, which stores global data used throughout compilation
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side tables | because the AST and HIR are immutable once created, we often carry extra information about them in the form of hashtables, indexed by the id of a particular node.
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side tables | because the AST and HIR are immutable once created, we often carry extra information about them in the form of hashtables, indexed by the id of a particular node.
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sigil | like a keyword but composed entirely of non-alphanumeric tokens. For example, `&` is a sigil for references.
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sigil | like a keyword but composed entirely of non-alphanumeric tokens. For example, `&` is a sigil for references.
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skolemization | a way of handling subtyping around "for-all" types (e.g., `for<'a> fn(&'a u32)`) as well as solving higher-ranked trait bounds (e.g., `for<'a> T: Trait<'a>`). See [the chapter on skolemization and universes](./borrow_check/region_inference.html#skol) for more details.
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skolemization | a way of handling subtyping around "for-all" types (e.g., `for<'a> fn(&'a u32)`) as well as solving higher-ranked trait bounds (e.g., `for<'a> T: Trait<'a>`). See [the chapter on skolemization and universes](../borrow_check/region_inference.html#skol) for more details.
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soundness | soundness is a technical term in type theory. Roughly, if a type system is sound, then if a program type-checks, it is type-safe; i.e. I can never (in safe rust) force a value into a variable of the wrong type. (see "completeness").
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soundness | soundness is a technical term in type theory. Roughly, if a type system is sound, then if a program type-checks, it is type-safe; i.e. I can never (in safe rust) force a value into a variable of the wrong type. (see "completeness").
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span | a location in the user's source code, used for error reporting primarily. These are like a file-name/line-number/column tuple on steroids: they carry a start/end point, and also track macro expansions and compiler desugaring. All while being packed into a few bytes (really, it's an index into a table). See the Span datatype for more.
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span | a location in the user's source code, used for error reporting primarily. These are like a file-name/line-number/column tuple on steroids: they carry a start/end point, and also track macro expansions and compiler desugaring. All while being packed into a few bytes (really, it's an index into a table). See the Span datatype for more.
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substs | the substitutions for a given generic type or item (e.g. the `i32`, `u32` in `HashMap<i32, u32>`)
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substs | the substitutions for a given generic type or item (e.g. the `i32`, `u32` in `HashMap<i32, u32>`)
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tcx | the "typing context", main data structure of the compiler ([see more](ty.html))
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tcx | the "typing context", main data structure of the compiler ([see more](../ty.html))
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'tcx | the lifetime of the currently active inference context ([see more](ty.html))
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'tcx | the lifetime of the currently active inference context ([see more](../ty.html))
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trait reference | the name of a trait along with a suitable set of input type/lifetimes ([see more](./traits/goals-and-clauses.html#trait-ref))
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trait reference | the name of a trait along with a suitable set of input type/lifetimes ([see more](../traits/goals-and-clauses.html#trait-ref))
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token | the smallest unit of parsing. Tokens are produced after lexing ([see more](the-parser.html)).
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token | the smallest unit of parsing. Tokens are produced after lexing ([see more](../the-parser.html)).
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[TLS] | Thread-Local Storage. Variables may be defined so that each thread has its own copy (rather than all threads sharing the variable). This has some interactions with LLVM. Not all platforms support TLS.
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[TLS] | Thread-Local Storage. Variables may be defined so that each thread has its own copy (rather than all threads sharing the variable). This has some interactions with LLVM. Not all platforms support TLS.
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trans | the code to translate MIR into LLVM IR. Renamed to codegen.
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trans | the code to translate MIR into LLVM IR. Renamed to codegen.
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trait reference | a trait and values for its type parameters ([see more](ty.html)).
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trait reference | a trait and values for its type parameters ([see more](../ty.html)).
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ty | the internal representation of a type ([see more](ty.html)).
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ty | the internal representation of a type ([see more](../ty.html)).
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UFCS | Universal Function Call Syntax. An unambiguous syntax for calling a method ([see more](type-checking.html)).
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UFCS | Universal Function Call Syntax. An unambiguous syntax for calling a method ([see more](../type-checking.html)).
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uninhabited type | a type which has _no_ values. This is not the same as a ZST, which has exactly 1 value. An example of an uninhabited type is `enum Foo {}`, which has no variants, and so, can never be created. The compiler can treat code that deals with uninhabited types as dead code, since there is no such value to be manipulated. `!` (the never type) is an uninhabited type. Uninhabited types are also called "empty types".
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uninhabited type | a type which has _no_ values. This is not the same as a ZST, which has exactly 1 value. An example of an uninhabited type is `enum Foo {}`, which has no variants, and so, can never be created. The compiler can treat code that deals with uninhabited types as dead code, since there is no such value to be manipulated. `!` (the never type) is an uninhabited type. Uninhabited types are also called "empty types".
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upvar | a variable captured by a closure from outside the closure.
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upvar | a variable captured by a closure from outside the closure.
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variance | variance determines how changes to a generic type/lifetime parameter affect subtyping; for example, if `T` is a subtype of `U`, then `Vec<T>` is a subtype `Vec<U>` because `Vec` is *covariant* in its generic parameter. See [the background chapter](./appendix/background.html#variance) for a more general explanation. See the [variance chapter](./variance.html) for an explanation of how type checking handles variance.
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variance | variance determines how changes to a generic type/lifetime parameter affect subtyping; for example, if `T` is a subtype of `U`, then `Vec<T>` is a subtype `Vec<U>` because `Vec` is *covariant* in its generic parameter. See [the background chapter](./background.html#variance) for a more general explanation. See the [variance chapter](../variance.html) for an explanation of how type checking handles variance.
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Wide pointer | a pointer with additional metadata. See "fat pointer" for more.
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Wide pointer | a pointer with additional metadata. See "fat pointer" for more.
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ZST | Zero-Sized Type. A type whose values have size 0 bytes. Since `2^0 = 1`, such types can have exactly one value. For example, `()` (unit) is a ZST. `struct Foo;` is also a ZST. The compiler can do some nice optimizations around ZSTs.
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ZST | Zero-Sized Type. A type whose values have size 0 bytes. Since `2^0 = 1`, such types can have exactly one value. For example, `()` (unit) is a ZST. `struct Foo;` is also a ZST. The compiler can do some nice optimizations around ZSTs.
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- More details to come, though the [NLL RFC] also includes fairly thorough
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- More details to come, though the [NLL RFC] also includes fairly thorough
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(and hopefully readable) coverage.
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(and hopefully readable) coverage.
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[fvb]: appendix/background.html#free-vs-bound
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[fvb]: ../appendix/background.html#free-vs-bound
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[NLL RFC]: http://rust-lang.github.io/rfcs/2094-nll.html
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[NLL RFC]: http://rust-lang.github.io/rfcs/2094-nll.html
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## Universal regions
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## Universal regions
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We handle this sort of subtyping by taking the variables that are
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We handle this sort of subtyping by taking the variables that are
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bound in the supertype and **skolemizing** them: this means that we
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bound in the supertype and **skolemizing** them: this means that we
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replace them with
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replace them with
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[universally quantified](appendix/background.html#quantified)
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[universally quantified](../appendix/background.html#quantified)
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representatives, written like `!1`. We call these regions "skolemized
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representatives, written like `!1`. We call these regions "skolemized
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regions" – they represent, basically, "some unknown region".
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regions" – they represent, basically, "some unknown region".
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So let's work through what happens next. To check if two functions are
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So let's work through what happens next. To check if two functions are
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subtypes, we check if their arguments have the desired relationship
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subtypes, we check if their arguments have the desired relationship
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(fn arguments are [contravariant](./appendix/background.html#variance), so
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(fn arguments are [contravariant](../appendix/background.html#variance), so
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we swap the left and right here):
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we swap the left and right here):
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||||||
```text
|
```text
|
||||||
|
|
@ -187,7 +187,7 @@ Here, the root universe would consist of the lifetimes `'static` and
|
||||||
the same concept to types, in which case the types `Foo` and `T` would
|
the same concept to types, in which case the types `Foo` and `T` would
|
||||||
be in the root universe (along with other global types, like `i32`).
|
be in the root universe (along with other global types, like `i32`).
|
||||||
Basically, the root universe contains all the names that
|
Basically, the root universe contains all the names that
|
||||||
[appear free](./appendix/background.html#free-vs-bound) in the body of `bar`.
|
[appear free](../appendix/background.html#free-vs-bound) in the body of `bar`.
|
||||||
|
|
||||||
Now let's extend `bar` a bit by adding a variable `x`:
|
Now let's extend `bar` a bit by adding a variable `x`:
|
||||||
|
|
||||||
|
|
|
||||||
|
|
@ -1,7 +1,7 @@
|
||||||
# The MIR (Mid-level IR)
|
# The MIR (Mid-level IR)
|
||||||
|
|
||||||
MIR is Rust's _Mid-level Intermediate Representation_. It is
|
MIR is Rust's _Mid-level Intermediate Representation_. It is
|
||||||
constructed from [HIR](./hir.html). MIR was introduced in
|
constructed from [HIR](../hir.html). MIR was introduced in
|
||||||
[RFC 1211]. It is a radically simplified form of Rust that is used for
|
[RFC 1211]. It is a radically simplified form of Rust that is used for
|
||||||
certain flow-sensitive safety checks – notably the borrow checker! –
|
certain flow-sensitive safety checks – notably the borrow checker! –
|
||||||
and also for optimization and code generation.
|
and also for optimization and code generation.
|
||||||
|
|
@ -26,7 +26,7 @@ Some of the key characteristics of MIR are:
|
||||||
- It does not have nested expressions.
|
- It does not have nested expressions.
|
||||||
- All types in MIR are fully explicit.
|
- All types in MIR are fully explicit.
|
||||||
|
|
||||||
[cfg]: ./appendix/background.html#cfg
|
[cfg]: ../appendix/background.html#cfg
|
||||||
|
|
||||||
## Key MIR vocabulary
|
## Key MIR vocabulary
|
||||||
|
|
||||||
|
|
@ -244,4 +244,4 @@ but [you can read about those below](#promoted)).
|
||||||
[mir]: https://github.com/rust-lang/rust/tree/master/src/librustc/mir
|
[mir]: https://github.com/rust-lang/rust/tree/master/src/librustc/mir
|
||||||
[mirmanip]: https://github.com/rust-lang/rust/tree/master/src/librustc_mir
|
[mirmanip]: https://github.com/rust-lang/rust/tree/master/src/librustc_mir
|
||||||
[mir]: https://github.com/rust-lang/rust/tree/master/src/librustc/mir
|
[mir]: https://github.com/rust-lang/rust/tree/master/src/librustc/mir
|
||||||
[newtype'd]: appendix/glossary.html
|
[newtype'd]: ../appendix/glossary.html
|
||||||
|
|
|
||||||
|
|
@ -156,7 +156,7 @@ then `mir_const_qualif(D)` would succeed if it came before
|
||||||
`mir_validated(D)`, but fail otherwise. Therefore, `mir_validated(D)`
|
`mir_validated(D)`, but fail otherwise. Therefore, `mir_validated(D)`
|
||||||
will **force** `mir_const_qualif` before it actually steals, thus
|
will **force** `mir_const_qualif` before it actually steals, thus
|
||||||
ensuring that the reads have already happened (remember that
|
ensuring that the reads have already happened (remember that
|
||||||
[queries are memoized](./query.html), so executing a query twice
|
[queries are memoized](../query.html), so executing a query twice
|
||||||
simply loads from a cache the second time):
|
simply loads from a cache the second time):
|
||||||
|
|
||||||
```text
|
```text
|
||||||
|
|
@ -174,4 +174,4 @@ alternatives in [rust-lang/rust#41710].
|
||||||
[rust-lang/rust#41710]: https://github.com/rust-lang/rust/issues/41710
|
[rust-lang/rust#41710]: https://github.com/rust-lang/rust/issues/41710
|
||||||
[mirtransform]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/transform/
|
[mirtransform]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/transform/
|
||||||
[`NoLandingPads`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/transform/no_landing_pads/struct.NoLandingPads.html
|
[`NoLandingPads`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/transform/no_landing_pads/struct.NoLandingPads.html
|
||||||
[MIR visitor]: mir/visitor.html
|
[MIR visitor]: ./visitor.html
|
||||||
|
|
|
||||||
|
|
@ -5,8 +5,8 @@ by the build system (`x.py test`). The main test harness for testing
|
||||||
the compiler itself is a tool called compiletest (sources in the
|
the compiler itself is a tool called compiletest (sources in the
|
||||||
[`src/tools/compiletest`]). This section gives a brief overview of how
|
[`src/tools/compiletest`]). This section gives a brief overview of how
|
||||||
the testing framework is setup, and then gets into some of the details
|
the testing framework is setup, and then gets into some of the details
|
||||||
on [how to run tests](./tests/running.html#ui) as well as
|
on [how to run tests](./running.html#ui) as well as
|
||||||
[how to add new tests](./tests/adding.html).
|
[how to add new tests](./adding.html).
|
||||||
|
|
||||||
[`src/tools/compiletest`]: https://github.com/rust-lang/rust/tree/master/src/tools/compiletest
|
[`src/tools/compiletest`]: https://github.com/rust-lang/rust/tree/master/src/tools/compiletest
|
||||||
|
|
||||||
|
|
@ -24,7 +24,7 @@ Here is a brief summary of the test suites as of this writing and what
|
||||||
they mean. In some cases, the test suites are linked to parts of the manual
|
they mean. In some cases, the test suites are linked to parts of the manual
|
||||||
that give more details.
|
that give more details.
|
||||||
|
|
||||||
- [`ui`](./tests/adding.html#ui) – tests that check the exact
|
- [`ui`](./adding.html#ui) – tests that check the exact
|
||||||
stdout/stderr from compilation and/or running the test
|
stdout/stderr from compilation and/or running the test
|
||||||
- `run-pass` – tests that are expected to compile and execute
|
- `run-pass` – tests that are expected to compile and execute
|
||||||
successfully (no panics)
|
successfully (no panics)
|
||||||
|
|
@ -59,7 +59,7 @@ including:
|
||||||
- **Tidy** – This is a custom tool used for validating source code
|
- **Tidy** – This is a custom tool used for validating source code
|
||||||
style and formatting conventions, such as rejecting long lines.
|
style and formatting conventions, such as rejecting long lines.
|
||||||
There is more information in the
|
There is more information in the
|
||||||
[section on coding conventions](./conventions.html#formatting).
|
[section on coding conventions](../conventions.html#formatting).
|
||||||
|
|
||||||
Example: `./x.py test src/tools/tidy`
|
Example: `./x.py test src/tools/tidy`
|
||||||
|
|
||||||
|
|
|
||||||
|
|
@ -17,7 +17,7 @@ type can be referenced by the user using an **associated type
|
||||||
projection** like `<Option<u32> as IntoIterator>::Item`. (Often,
|
projection** like `<Option<u32> as IntoIterator>::Item`. (Often,
|
||||||
though, people will use the shorthand syntax `T::Item` – presently,
|
though, people will use the shorthand syntax `T::Item` – presently,
|
||||||
that syntax is expanded during
|
that syntax is expanded during
|
||||||
["type collection"](./type-checking.html) into the explicit form,
|
["type collection"](../type-checking.html) into the explicit form,
|
||||||
though that is something we may want to change in the future.)
|
though that is something we may want to change in the future.)
|
||||||
|
|
||||||
[intoiter-item]: https://doc.rust-lang.org/nightly/core/iter/trait.IntoIterator.html#associatedtype.Item
|
[intoiter-item]: https://doc.rust-lang.org/nightly/core/iter/trait.IntoIterator.html#associatedtype.Item
|
||||||
|
|
@ -130,7 +130,7 @@ any given associated item.
|
||||||
|
|
||||||
Now we are ready to discuss how associated type equality integrates
|
Now we are ready to discuss how associated type equality integrates
|
||||||
with unification. As described in the
|
with unification. As described in the
|
||||||
[type inference](./type-inference.html) section, unification is
|
[type inference](../type-inference.html) section, unification is
|
||||||
basically a procedure with a signature like this:
|
basically a procedure with a signature like this:
|
||||||
|
|
||||||
```text
|
```text
|
||||||
|
|
|
||||||
|
|
@ -24,7 +24,7 @@ On the other hand, if there is no hit, we need to go through the [selection
|
||||||
process] from scratch. Suppose, we come to the conclusion that the only
|
process] from scratch. Suppose, we come to the conclusion that the only
|
||||||
possible impl is this one, with def-id 22:
|
possible impl is this one, with def-id 22:
|
||||||
|
|
||||||
[selection process]: ./traits/resolution.html#selection
|
[selection process]: ./resolution.html#selection
|
||||||
|
|
||||||
```rust,ignore
|
```rust,ignore
|
||||||
impl Foo<isize> for usize { ... } // Impl #22
|
impl Foo<isize> for usize { ... } // Impl #22
|
||||||
|
|
@ -34,7 +34,7 @@ We would then record in the cache `usize : Foo<$0> => ImplCandidate(22)`. Next
|
||||||
we would [confirm] `ImplCandidate(22)`, which would (as a side-effect) unify
|
we would [confirm] `ImplCandidate(22)`, which would (as a side-effect) unify
|
||||||
`$t` with `isize`.
|
`$t` with `isize`.
|
||||||
|
|
||||||
[confirm]: ./traits/resolution.html#confirmation
|
[confirm]: ./resolution.html#confirmation
|
||||||
|
|
||||||
Now, at some later time, we might come along and see a `usize :
|
Now, at some later time, we might come along and see a `usize :
|
||||||
Foo<$u>`. When skolemized, this would yield `usize : Foo<$0>`, just as
|
Foo<$u>`. When skolemized, this would yield `usize : Foo<$0>`, just as
|
||||||
|
|
@ -61,7 +61,7 @@ to be pretty clearly safe and also still retains a very high hit rate
|
||||||
**TODO**: it looks like `pick_candidate_cache` no longer exists. In
|
**TODO**: it looks like `pick_candidate_cache` no longer exists. In
|
||||||
general, is this section still accurate at all?
|
general, is this section still accurate at all?
|
||||||
|
|
||||||
[`ParamEnv`]: ./param_env.html
|
[`ParamEnv`]: ../param_env.html
|
||||||
[`tcx`]: ./ty.html
|
[`tcx`]: ../ty.html
|
||||||
[#18290]: https://github.com/rust-lang/rust/issues/18290
|
[#18290]: https://github.com/rust-lang/rust/issues/18290
|
||||||
[#22019]: https://github.com/rust-lang/rust/issues/22019
|
[#22019]: https://github.com/rust-lang/rust/issues/22019
|
||||||
|
|
|
||||||
|
|
@ -3,11 +3,11 @@
|
||||||
The "start" of the trait system is the **canonical query** (these are
|
The "start" of the trait system is the **canonical query** (these are
|
||||||
both queries in the more general sense of the word – something you
|
both queries in the more general sense of the word – something you
|
||||||
would like to know the answer to – and in the
|
would like to know the answer to – and in the
|
||||||
[rustc-specific sense](./query.html)). The idea is that the type
|
[rustc-specific sense](../query.html)). The idea is that the type
|
||||||
checker or other parts of the system, may in the course of doing their
|
checker or other parts of the system, may in the course of doing their
|
||||||
thing want to know whether some trait is implemented for some type
|
thing want to know whether some trait is implemented for some type
|
||||||
(e.g., is `u32: Debug` true?). Or they may want to
|
(e.g., is `u32: Debug` true?). Or they may want to
|
||||||
[normalize some associated type](./traits/associated-types.html).
|
[normalize some associated type](./associated-types.html).
|
||||||
|
|
||||||
This section covers queries at a fairly high level of abstraction. The
|
This section covers queries at a fairly high level of abstraction. The
|
||||||
subsections look a bit more closely at how these ideas are implemented
|
subsections look a bit more closely at how these ideas are implemented
|
||||||
|
|
@ -106,7 +106,7 @@ value for a type variable, that means that this is the **only possible
|
||||||
instantiation** that you could use, given the current set of impls and
|
instantiation** that you could use, given the current set of impls and
|
||||||
where-clauses, that would be provable. (Internally within the solver,
|
where-clauses, that would be provable. (Internally within the solver,
|
||||||
though, they can potentially enumerate all possible answers. See
|
though, they can potentially enumerate all possible answers. See
|
||||||
[the description of the SLG solver](./traits/slg.html) for details.)
|
[the description of the SLG solver](./slg.html) for details.)
|
||||||
|
|
||||||
The response to a trait query in rustc is typically a
|
The response to a trait query in rustc is typically a
|
||||||
`Result<QueryResult<T>, NoSolution>` (where the `T` will vary a bit
|
`Result<QueryResult<T>, NoSolution>` (where the `T` will vary a bit
|
||||||
|
|
@ -132,7 +132,7 @@ we did find. It consists of four parts:
|
||||||
- **Region constraints:** these are relations that must hold between
|
- **Region constraints:** these are relations that must hold between
|
||||||
the lifetimes that you supplied as inputs. We'll ignore these here,
|
the lifetimes that you supplied as inputs. We'll ignore these here,
|
||||||
but see the
|
but see the
|
||||||
[section on handling regions in traits](./traits/regions.html) for
|
[section on handling regions in traits](./regions.html) for
|
||||||
more details.
|
more details.
|
||||||
- **Value:** The query result also comes with a value of type `T`. For
|
- **Value:** The query result also comes with a value of type `T`. For
|
||||||
some specialized queries – like normalizing associated types –
|
some specialized queries – like normalizing associated types –
|
||||||
|
|
@ -219,7 +219,7 @@ As a result of this assignment, the type of `u` is forced to be
|
||||||
`Option<Vec<?V>>`, where `?V` represents the element type of the
|
`Option<Vec<?V>>`, where `?V` represents the element type of the
|
||||||
vector. This in turn implies that `?U` is [unified] to `Vec<?V>`.
|
vector. This in turn implies that `?U` is [unified] to `Vec<?V>`.
|
||||||
|
|
||||||
[unified]: ./type-checking.html
|
[unified]: ../type-checking.html
|
||||||
|
|
||||||
Let's suppose that the type checker decides to revisit the
|
Let's suppose that the type checker decides to revisit the
|
||||||
"as-yet-unproven" trait obligation we saw before, `Vec<?T>:
|
"as-yet-unproven" trait obligation we saw before, `Vec<?T>:
|
||||||
|
|
|
||||||
|
|
@ -6,7 +6,7 @@ from its context. It is a key part of implementing
|
||||||
to get more context.
|
to get more context.
|
||||||
|
|
||||||
Canonicalization is really based on a very simple concept: every
|
Canonicalization is really based on a very simple concept: every
|
||||||
[inference variable](./type-inference.html#vars) is always in one of
|
[inference variable](../type-inference.html#vars) is always in one of
|
||||||
two states: either it is **unbound**, in which case we don't know yet
|
two states: either it is **unbound**, in which case we don't know yet
|
||||||
what type it is, or it is **bound**, in which case we do. So to
|
what type it is, or it is **bound**, in which case we do. So to
|
||||||
isolate some data-structure T that contains types/regions from its
|
isolate some data-structure T that contains types/regions from its
|
||||||
|
|
@ -16,7 +16,7 @@ starting from zero and numbered in a fixed order (left to right, for
|
||||||
the most part, but really it doesn't matter as long as it is
|
the most part, but really it doesn't matter as long as it is
|
||||||
consistent).
|
consistent).
|
||||||
|
|
||||||
[cq]: ./traits/canonical-queries.html
|
[cq]: ./canonical-queries.html
|
||||||
|
|
||||||
So, for example, if we have the type `X = (?T, ?U)`, where `?T` and
|
So, for example, if we have the type `X = (?T, ?U)`, where `?T` and
|
||||||
`?U` are distinct, unbound inference variables, then the canonical
|
`?U` are distinct, unbound inference variables, then the canonical
|
||||||
|
|
@ -41,7 +41,7 @@ trait query: `?A: Foo<'static, ?B>`, where `?A` and `?B` are unbound.
|
||||||
This query contains two unbound variables, but it also contains the
|
This query contains two unbound variables, but it also contains the
|
||||||
lifetime `'static`. The trait system generally ignores all lifetimes
|
lifetime `'static`. The trait system generally ignores all lifetimes
|
||||||
and treats them equally, so when canonicalizing, we will *also*
|
and treats them equally, so when canonicalizing, we will *also*
|
||||||
replace any [free lifetime](./appendix/background.html#free-vs-bound) with a
|
replace any [free lifetime](../appendix/background.html#free-vs-bound) with a
|
||||||
canonical variable. Therefore, we get the following result:
|
canonical variable. Therefore, we get the following result:
|
||||||
|
|
||||||
```text
|
```text
|
||||||
|
|
@ -98,12 +98,12 @@ Remember that substitution S though! We're going to need it later.
|
||||||
|
|
||||||
OK, now that we have a fresh inference context and an instantiated
|
OK, now that we have a fresh inference context and an instantiated
|
||||||
query, we can go ahead and try to solve it. The trait solver itself is
|
query, we can go ahead and try to solve it. The trait solver itself is
|
||||||
explained in more detail in [another section](./traits/slg.html), but
|
explained in more detail in [another section](./slg.html), but
|
||||||
suffice to say that it will compute a [certainty value][cqqr] (`Proven` or
|
suffice to say that it will compute a [certainty value][cqqr] (`Proven` or
|
||||||
`Ambiguous`) and have side-effects on the inference variables we've
|
`Ambiguous`) and have side-effects on the inference variables we've
|
||||||
created. For example, if there were only one impl of `Foo`, like so:
|
created. For example, if there were only one impl of `Foo`, like so:
|
||||||
|
|
||||||
[cqqr]: ./traits/canonical-queries.html#query-response
|
[cqqr]: ./canonical-queries.html#query-response
|
||||||
|
|
||||||
```rust,ignore
|
```rust,ignore
|
||||||
impl<'a, X> Foo<'a, X> for Vec<X>
|
impl<'a, X> Foo<'a, X> for Vec<X>
|
||||||
|
|
|
||||||
|
|
@ -131,18 +131,18 @@ See [The SLG Solver][slg].
|
||||||
|
|
||||||
[rustc-issues]: https://github.com/rust-lang-nursery/rustc-guide/issues
|
[rustc-issues]: https://github.com/rust-lang-nursery/rustc-guide/issues
|
||||||
[chalk]: https://github.com/rust-lang-nursery/chalk
|
[chalk]: https://github.com/rust-lang-nursery/chalk
|
||||||
[lowering-to-logic]: traits/lowering-to-logic.html
|
[lowering-to-logic]: ./lowering-to-logic.html
|
||||||
[lowering-rules]: traits/lowering-rules.html
|
[lowering-rules]: ./lowering-rules.html
|
||||||
[ast]: https://en.wikipedia.org/wiki/Abstract_syntax_tree
|
[ast]: https://en.wikipedia.org/wiki/Abstract_syntax_tree
|
||||||
[chalk-ast]: https://github.com/rust-lang-nursery/chalk/blob/master/chalk-parse/src/ast.rs
|
[chalk-ast]: https://github.com/rust-lang-nursery/chalk/blob/master/chalk-parse/src/ast.rs
|
||||||
[universal quantification]: https://en.wikipedia.org/wiki/Universal_quantification
|
[universal quantification]: https://en.wikipedia.org/wiki/Universal_quantification
|
||||||
[lowering-forall]: ./traits/lowering-to-logic.html#type-checking-generic-functions-beyond-horn-clauses
|
[lowering-forall]: ./lowering-to-logic.html#type-checking-generic-functions-beyond-horn-clauses
|
||||||
[programclause]: https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/ir.rs#L721
|
[programclause]: https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/ir.rs#L721
|
||||||
[clause]: https://github.com/rust-lang-nursery/chalk/blob/master/GLOSSARY.md#clause
|
[clause]: https://github.com/rust-lang-nursery/chalk/blob/master/GLOSSARY.md#clause
|
||||||
[goals-and-clauses]: ./traits/goals-and-clauses.html
|
[goals-and-clauses]: ./goals-and-clauses.html
|
||||||
[well-formedness-checks]: https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/ir/lowering.rs#L230-L232
|
[well-formedness-checks]: https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/ir/lowering.rs#L230-L232
|
||||||
[ir-code]: https://github.com/rust-lang-nursery/chalk/blob/master/src/ir.rs
|
[ir-code]: https://github.com/rust-lang-nursery/chalk/blob/master/src/ir.rs
|
||||||
[HIR]: hir.html
|
[HIR]: ../hir.html
|
||||||
[binders-struct]: https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/ir.rs#L661
|
[binders-struct]: https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/ir.rs#L661
|
||||||
[rules-environment]: https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/rules.rs#L9
|
[rules-environment]: https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/rules.rs#L9
|
||||||
[slg]: ./traits/slg.html
|
[slg]: ./slg.html
|
||||||
|
|
|
||||||
|
|
@ -2,7 +2,7 @@
|
||||||
|
|
||||||
In logic programming terms, a **goal** is something that you must
|
In logic programming terms, a **goal** is something that you must
|
||||||
prove and a **clause** is something that you know is true. As
|
prove and a **clause** is something that you know is true. As
|
||||||
described in the [lowering to logic](./traits/lowering-to-logic.html)
|
described in the [lowering to logic](./lowering-to-logic.html)
|
||||||
chapter, Rust's trait solver is based on an extension of hereditary
|
chapter, Rust's trait solver is based on an extension of hereditary
|
||||||
harrop (HH) clauses, which extend traditional Prolog Horn clauses with
|
harrop (HH) clauses, which extend traditional Prolog Horn clauses with
|
||||||
a few new superpowers.
|
a few new superpowers.
|
||||||
|
|
@ -37,7 +37,7 @@ paper
|
||||||
["A Proof Procedure for the Logic of Hereditary Harrop Formulas"][pphhf]
|
["A Proof Procedure for the Logic of Hereditary Harrop Formulas"][pphhf]
|
||||||
gives the details.
|
gives the details.
|
||||||
|
|
||||||
[pphhf]: ./traits/bibliography.html#pphhf
|
[pphhf]: ./bibliography.html#pphhf
|
||||||
|
|
||||||
<a name="domain-goals"></a>
|
<a name="domain-goals"></a>
|
||||||
|
|
||||||
|
|
@ -94,7 +94,7 @@ e.g. `ProjectionEq<T as Iterator>::Item = u8`
|
||||||
|
|
||||||
The given associated type `Projection` is equal to `Type`; this can be proved
|
The given associated type `Projection` is equal to `Type`; this can be proved
|
||||||
with either normalization or using skolemized types. See [the section
|
with either normalization or using skolemized types. See [the section
|
||||||
on associated types](./traits/associated-types.html).
|
on associated types](./associated-types.html).
|
||||||
|
|
||||||
#### Normalize(Projection -> Type)
|
#### Normalize(Projection -> Type)
|
||||||
e.g. `ProjectionEq<T as Iterator>::Item -> u8`
|
e.g. `ProjectionEq<T as Iterator>::Item -> u8`
|
||||||
|
|
@ -102,12 +102,12 @@ e.g. `ProjectionEq<T as Iterator>::Item -> u8`
|
||||||
The given associated type `Projection` can be [normalized][n] to `Type`.
|
The given associated type `Projection` can be [normalized][n] to `Type`.
|
||||||
|
|
||||||
As discussed in [the section on associated
|
As discussed in [the section on associated
|
||||||
types](./traits/associated-types.html), `Normalize` implies `ProjectionEq`,
|
types](./associated-types.html), `Normalize` implies `ProjectionEq`,
|
||||||
but not vice versa. In general, proving `Normalize(<T as Trait>::Item -> U)`
|
but not vice versa. In general, proving `Normalize(<T as Trait>::Item -> U)`
|
||||||
also requires proving `Implemented(T: Trait)`.
|
also requires proving `Implemented(T: Trait)`.
|
||||||
|
|
||||||
[n]: ./traits/associated-types.html#normalize
|
[n]: ./associated-types.html#normalize
|
||||||
[at]: ./traits/associated-types.html
|
[at]: ./associated-types.html
|
||||||
|
|
||||||
#### FromEnv(TraitRef), FromEnv(Projection = Type)
|
#### FromEnv(TraitRef), FromEnv(Projection = Type)
|
||||||
e.g. `FromEnv(Self: Add<i32>)`
|
e.g. `FromEnv(Self: Add<i32>)`
|
||||||
|
|
@ -212,7 +212,7 @@ In addition to auto traits, `WellFormed` predicates are co-inductive.
|
||||||
These are used to achieve a similar "enumerate all the cases" pattern,
|
These are used to achieve a similar "enumerate all the cases" pattern,
|
||||||
as described in the section on [implied bounds].
|
as described in the section on [implied bounds].
|
||||||
|
|
||||||
[implied bounds]: ./traits/lowering-rules.html#implied-bounds
|
[implied bounds]: ./lowering-rules.html#implied-bounds
|
||||||
|
|
||||||
## Incomplete chapter
|
## Incomplete chapter
|
||||||
|
|
||||||
|
|
|
||||||
|
|
@ -4,7 +4,7 @@
|
||||||
[process of being implemented][wg]; this chapter serves as a kind of
|
[process of being implemented][wg]; this chapter serves as a kind of
|
||||||
in-progress design document. If you would prefer to read about how the
|
in-progress design document. If you would prefer to read about how the
|
||||||
current trait solver works, check out
|
current trait solver works, check out
|
||||||
[this other chapter](./traits/resolution.html). (By the way, if you
|
[this other chapter](./resolution.html). (By the way, if you
|
||||||
would like to help in hacking on the new solver, you will find
|
would like to help in hacking on the new solver, you will find
|
||||||
instructions for getting involved in the
|
instructions for getting involved in the
|
||||||
[Traits Working Group tracking issue][wg].) 🚧
|
[Traits Working Group tracking issue][wg].) 🚧
|
||||||
|
|
@ -13,20 +13,20 @@ instructions for getting involved in the
|
||||||
|
|
||||||
Trait solving is based around a few key ideas:
|
Trait solving is based around a few key ideas:
|
||||||
|
|
||||||
- [Lowering to logic](./traits/lowering-to-logic.html), which expresses
|
- [Lowering to logic](./lowering-to-logic.html), which expresses
|
||||||
Rust traits in terms of standard logical terms.
|
Rust traits in terms of standard logical terms.
|
||||||
- The [goals and clauses](./traits/goals-and-clauses.html) chapter
|
- The [goals and clauses](./goals-and-clauses.html) chapter
|
||||||
describes the precise form of rules we use, and
|
describes the precise form of rules we use, and
|
||||||
[lowering rules](./traits/lowering-rules.html) gives the complete set of
|
[lowering rules](./lowering-rules.html) gives the complete set of
|
||||||
lowering rules in a more reference-like form.
|
lowering rules in a more reference-like form.
|
||||||
- [Canonical queries](./traits/canonical-queries.html), which allow us
|
- [Canonical queries](./canonical-queries.html), which allow us
|
||||||
to solve trait problems (like "is `Foo` implemented for the type
|
to solve trait problems (like "is `Foo` implemented for the type
|
||||||
`Bar`?") once, and then apply that same result independently in many
|
`Bar`?") once, and then apply that same result independently in many
|
||||||
different inference contexts.
|
different inference contexts.
|
||||||
- [Lazy normalization](./traits/associated-types.html), which is the
|
- [Lazy normalization](./associated-types.html), which is the
|
||||||
technique we use to accommodate associated types when figuring out
|
technique we use to accommodate associated types when figuring out
|
||||||
whether types are equal.
|
whether types are equal.
|
||||||
- [Region constraints](./traits/regions.html), which are accumulated
|
- [Region constraints](./regions.html), which are accumulated
|
||||||
during trait solving but mostly ignored. This means that trait
|
during trait solving but mostly ignored. This means that trait
|
||||||
solving effectively ignores the precise regions involved, always –
|
solving effectively ignores the precise regions involved, always –
|
||||||
but we still remember the constraints on them so that those
|
but we still remember the constraints on them so that those
|
||||||
|
|
|
||||||
|
|
@ -1,7 +1,7 @@
|
||||||
# The lowering module in rustc
|
# The lowering module in rustc
|
||||||
|
|
||||||
The program clauses described in the
|
The program clauses described in the
|
||||||
[lowering rules](./traits/lowering-rules.html) section are actually
|
[lowering rules](./lowering-rules.html) section are actually
|
||||||
created in the [`rustc_traits::lowering`][lowering] module.
|
created in the [`rustc_traits::lowering`][lowering] module.
|
||||||
|
|
||||||
[lowering]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_traits/lowering/
|
[lowering]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_traits/lowering/
|
||||||
|
|
@ -16,7 +16,7 @@ query is invoked on a `DefId` that identifies something like a trait,
|
||||||
an impl, or an associated item definition. It then produces and
|
an impl, or an associated item definition. It then produces and
|
||||||
returns a vector of program clauses.
|
returns a vector of program clauses.
|
||||||
|
|
||||||
[query]: ./query.html
|
[query]: ../query.html
|
||||||
|
|
||||||
<a name="unit-tests"></a>
|
<a name="unit-tests"></a>
|
||||||
|
|
||||||
|
|
|
||||||
|
|
@ -4,8 +4,8 @@ This section gives the complete lowering rules for Rust traits into
|
||||||
[program clauses][pc]. It is a kind of reference. These rules
|
[program clauses][pc]. It is a kind of reference. These rules
|
||||||
reference the [domain goals][dg] defined in an earlier section.
|
reference the [domain goals][dg] defined in an earlier section.
|
||||||
|
|
||||||
[pc]: ./traits/goals-and-clauses.html
|
[pc]: ./goals-and-clauses.html
|
||||||
[dg]: ./traits/goals-and-clauses.html#domain-goals
|
[dg]: ./goals-and-clauses.html#domain-goals
|
||||||
|
|
||||||
## Notation
|
## Notation
|
||||||
|
|
||||||
|
|
@ -16,7 +16,7 @@ The nonterminal `Ai` is used to mean some generic *argument*, which
|
||||||
might be a lifetime like `'a` or a type like `Vec<A>`.
|
might be a lifetime like `'a` or a type like `Vec<A>`.
|
||||||
|
|
||||||
When defining the lowering rules, we will give goals and clauses in
|
When defining the lowering rules, we will give goals and clauses in
|
||||||
the [notation given in this section](./traits/goals-and-clauses.html).
|
the [notation given in this section](./goals-and-clauses.html).
|
||||||
We sometimes insert "macros" like `LowerWhereClause!` into these
|
We sometimes insert "macros" like `LowerWhereClause!` into these
|
||||||
definitions; these macros reference other sections within this chapter.
|
definitions; these macros reference other sections within this chapter.
|
||||||
|
|
||||||
|
|
@ -141,7 +141,7 @@ This `WellFormed` rule states that `T: Trait` is well-formed if (a)
|
||||||
`T: Trait` is implemented and (b) all the where-clauses declared on
|
`T: Trait` is implemented and (b) all the where-clauses declared on
|
||||||
`Trait` are well-formed (and hence they are implemented). Remember
|
`Trait` are well-formed (and hence they are implemented). Remember
|
||||||
that the `WellFormed` predicate is
|
that the `WellFormed` predicate is
|
||||||
[coinductive](./traits/goals-and-clauses.html#coinductive); in this
|
[coinductive](./goals-and-clauses.html#coinductive); in this
|
||||||
case, it is serving as a kind of "carrier" that allows us to enumerate
|
case, it is serving as a kind of "carrier" that allows us to enumerate
|
||||||
all the where clauses that are transitively implied by `T: Trait`.
|
all the where clauses that are transitively implied by `T: Trait`.
|
||||||
|
|
||||||
|
|
@ -266,7 +266,7 @@ where WC
|
||||||
|
|
||||||
We will produce a number of program clauses. The first two define
|
We will produce a number of program clauses. The first two define
|
||||||
the rules by which `ProjectionEq` can succeed; these two clauses are discussed
|
the rules by which `ProjectionEq` can succeed; these two clauses are discussed
|
||||||
in detail in the [section on associated types](./traits/associated-types.html),
|
in detail in the [section on associated types](./associated-types.html),
|
||||||
but reproduced here for reference:
|
but reproduced here for reference:
|
||||||
|
|
||||||
```text
|
```text
|
||||||
|
|
|
||||||
|
|
@ -170,8 +170,8 @@ example Gopalan Nadathur's excellent
|
||||||
["A Proof Procedure for the Logic of Hereditary Harrop Formulas"][pphhf]
|
["A Proof Procedure for the Logic of Hereditary Harrop Formulas"][pphhf]
|
||||||
in [the bibliography].
|
in [the bibliography].
|
||||||
|
|
||||||
[the bibliography]: ./traits/bibliography.html
|
[the bibliography]: ./bibliography.html
|
||||||
[pphhf]: ./traits/bibliography.html#pphhf
|
[pphhf]: ./bibliography.html#pphhf
|
||||||
|
|
||||||
It turns out that supporting FOHH is not really all that hard. And
|
It turns out that supporting FOHH is not really all that hard. And
|
||||||
once we are able to do that, we can easily describe the type-checking
|
once we are able to do that, we can easily describe the type-checking
|
||||||
|
|
|
||||||
|
|
@ -6,7 +6,7 @@ some non-obvious things.
|
||||||
**Note:** This chapter (and its subchapters) describe how the trait
|
**Note:** This chapter (and its subchapters) describe how the trait
|
||||||
solver **currently** works. However, we are in the process of
|
solver **currently** works. However, we are in the process of
|
||||||
designing a new trait solver. If you'd prefer to read about *that*,
|
designing a new trait solver. If you'd prefer to read about *that*,
|
||||||
see [*this* traits chapter](./traits/index.html).
|
see [*this* traits chapter](./index.html).
|
||||||
|
|
||||||
## Major concepts
|
## Major concepts
|
||||||
|
|
||||||
|
|
@ -220,7 +220,7 @@ in that list. If so, it is considered satisfied. More precisely, we
|
||||||
want to check whether there is a where-clause obligation that is for
|
want to check whether there is a where-clause obligation that is for
|
||||||
the same trait (or some subtrait) and which can match against the obligation.
|
the same trait (or some subtrait) and which can match against the obligation.
|
||||||
|
|
||||||
[parameter environment]: ./param_env.html
|
[parameter environment]: ../param_env.html
|
||||||
|
|
||||||
Consider this simple example:
|
Consider this simple example:
|
||||||
|
|
||||||
|
|
|
||||||
Loading…
Reference in New Issue