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Make instructions for configuring compiler for debug more explicit

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Ryan Levick 2021-01-04 16:47:55 +01:00 committed by Joshua Nelson
parent 92e47a0559
commit 468faaea87
1 changed files with 20 additions and 10 deletions
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src/compiler-debugging.md
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@ -7,6 +7,21 @@ advice about specific parts of the compiler (e.g. the [Queries Debugging and
Testing chapter](./incrcomp-debugging.html) or the [LLVM Debugging
chapter](./backend/debugging.md)).
## Configuring the compiler
By default, rustc is built without most debug information. To enable debug info,
set `debug = true` in your config.toml.
Setting `debug = true` turns on many different debug options (e.g., `debug-assertions`,
`debug-logging`, etc.) which can be individually tweaked if you want to, but many people
simply set `debug = true`. Check out the comments in `config.toml.example` for more info.
In some cases, just setting these options will not trigger a rebuild,
so if you changed it and you already have a compiler built, you might
want to call `x.py clean` to force a rebuild.
You will need to rebuild the compiler once you've changed any configuration options.
## `-Z` flags
The compiler has a bunch of `-Z` flags. These are unstable flags that are only
@ -25,8 +40,8 @@ normal Rust programs. IIRC backtraces **don't work** on MinGW,
sorry. If you have trouble or the backtraces are full of `unknown`,
you might want to find some way to use Linux, Mac, or MSVC on Windows.
In the default configuration, you don't have line numbers enabled, so the
backtrace looks like this:
In the default configuration (without `debug` set to `true`), you don't have line numbers
enabled, so the backtrace looks like this:
```text
stack backtrace:
@ -45,10 +60,9 @@ stack backtrace:
37: rustc_driver::run_compiler
```
If you want line numbers for the stack trace, you can enable `debug = true` in
your config.toml and rebuild the compiler (`debuginfo-level = 1` will also add
line numbers, but `debug = true` gives full debuginfo). Then the backtrace will
look like this:
If you set `debug = true`, you will get line numbers for the stack trace.
`debuginfo-level = 1` will also add line numbers, but `debug = true` gives
full debug info. Then the backtrace will look like this:
```text
stack backtrace:
@ -260,10 +274,6 @@ if you run the compiler with `RUSTC_LOG=rustc rustc some.rs` and only see
`INFO` logs, make sure that `debug-logging=true` is turned on in your
config.toml.
In some cases, just setting it will not trigger a rebuild,
so if you changed it and you already have a compiler built, you might
want to call `x.py clean` to force one.
### Logging etiquette and conventions
Because calls to `debug!` are removed by default, in most cases, don't worry