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go/types: better error position for instantiation failure 

This is a port of CL 366757 from types2 to go/types,
adjusted for the different handling of index expressions
in go/types.

For #49179.

Change-Id: Ic859eb09683134d055e28c8e0cb1f3814a87dc5c
Reviewed-on: https://go-review.googlesource.com/c/go/+/367198
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-11-26 13:14:01 -08:00
parent 1ab677a797
commit bc32dd1b69
7 changed files with 45 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/go/types/builtins.go
View File

@ -130,7 +130,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
arg(&x, i)
xlist = append(xlist, &x)
}
check.arguments(call, sig, nil, xlist) // discard result (we know the result type)
check.arguments(call, sig, nil, xlist, nil) // discard result (we know the result type)
// ok to continue even if check.arguments reported errors
x.mode = value

39
src/go/types/call.go
View File

@ -51,16 +51,8 @@ func (check *Checker) funcInst(x *operand, ix *typeparams.IndexExpr) {
}
assert(got == want)
// determine argument positions (for error reporting)
// TODO(rFindley) use a positioner here? instantiate would need to be
// updated accordingly.
poslist := make([]token.Pos, len(ix.Indices))
for i, x := range ix.Indices {
poslist[i] = x.Pos()
}
// instantiate function signature
res := check.instantiateSignature(x.Pos(), sig, targs, poslist)
res := check.instantiateSignature(x.Pos(), sig, targs, ix.Indices)
assert(res.TypeParams().Len() == 0) // signature is not generic anymore
check.recordInstance(ix.Orig, targs, res)
x.typ = res
@ -68,7 +60,7 @@ func (check *Checker) funcInst(x *operand, ix *typeparams.IndexExpr) {
x.expr = ix.Orig
}
func (check *Checker) instantiateSignature(pos token.Pos, typ *Signature, targs []Type, posList []token.Pos) (res *Signature) {
func (check *Checker) instantiateSignature(pos token.Pos, typ *Signature, targs []Type, xlist []ast.Expr) (res *Signature) {
assert(check != nil)
assert(len(targs) == typ.TypeParams().Len())
@ -82,17 +74,17 @@ func (check *Checker) instantiateSignature(pos token.Pos, typ *Signature, targs
}
inst := check.instance(pos, typ, targs, check.bestContext(nil)).(*Signature)
assert(len(posList) <= len(targs))
assert(len(xlist) <= len(targs))
tparams := typ.TypeParams().list()
if i, err := check.verify(pos, tparams, targs); err != nil {
// best position for error reporting
pos := pos
if i < len(posList) {
pos = posList[i]
if i < len(xlist) {
pos = xlist[i].Pos()
}
check.softErrorf(atPos(pos), _InvalidTypeArg, err.Error())
check.softErrorf(atPos(pos), _InvalidTypeArg, "%s", err)
} else {
check.mono.recordInstance(check.pkg, pos, tparams, targs, posList)
check.mono.recordInstance(check.pkg, pos, tparams, targs, xlist)
}
return inst
@ -184,21 +176,23 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
}
// evaluate type arguments, if any
var xlist []ast.Expr
var targs []Type
if ix != nil {
targs = check.typeList(ix.Indices)
xlist = ix.Indices
targs = check.typeList(xlist)
if targs == nil {
check.use(call.Args...)
x.mode = invalid
x.expr = call
return statement
}
assert(len(targs) == len(ix.Indices))
assert(len(targs) == len(xlist))
// check number of type arguments (got) vs number of type parameters (want)
got, want := len(targs), sig.TypeParams().Len()
if got > want {
check.errorf(ix.Indices[want], _WrongTypeArgCount, "got %d type arguments but want %d", got, want)
check.errorf(xlist[want], _WrongTypeArgCount, "got %d type arguments but want %d", got, want)
check.use(call.Args...)
x.mode = invalid
x.expr = call
@ -209,7 +203,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
// evaluate arguments
args, _ := check.exprList(call.Args, false)
isGeneric := sig.TypeParams().Len() > 0
sig = check.arguments(call, sig, targs, args)
sig = check.arguments(call, sig, targs, args, xlist)
if isGeneric && sig.TypeParams().Len() == 0 {
// Update the recorded type of call.Fun to its instantiated type.
@ -286,7 +280,8 @@ func (check *Checker) exprList(elist []ast.Expr, allowCommaOk bool) (xlist []*op
return
}
func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type, args []*operand) (rsig *Signature) {
// xlist is the list of type argument expressions supplied in the source code.
func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type, args []*operand, xlist []ast.Expr) (rsig *Signature) {
rsig = sig
// TODO(gri) try to eliminate this extra verification loop
@ -388,15 +383,13 @@ func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type
check.softErrorf(inNode(call, call.Lparen), _UnsupportedFeature, "implicit function instantiation requires go1.18 or later")
}
}
// TODO(gri) provide position information for targs so we can feed
// it to the instantiate call for better error reporting
targs := check.infer(call, sig.TypeParams().list(), targs, sigParams, args)
if targs == nil {
return // error already reported
}
// compute result signature
rsig = check.instantiateSignature(call.Pos(), sig, targs, nil)
rsig = check.instantiateSignature(call.Pos(), sig, targs, xlist)
assert(rsig.TypeParams().Len() == 0) // signature is not generic anymore
check.recordInstance(call.Fun, targs, rsig)

7
src/go/types/mono.go
View File

@ -5,6 +5,7 @@
package types
import (
"go/ast"
"go/token"
)
@ -166,11 +167,11 @@ func (w *monoGraph) recordCanon(mpar, tpar *TypeParam) {
// recordInstance records that the given type parameters were
// instantiated with the corresponding type arguments.
func (w *monoGraph) recordInstance(pkg *Package, pos token.Pos, tparams []*TypeParam, targs []Type, posList []token.Pos) {
func (w *monoGraph) recordInstance(pkg *Package, pos token.Pos, tparams []*TypeParam, targs []Type, xlist []ast.Expr) {
for i, tpar := range tparams {
pos := pos
if i < len(posList) {
pos = posList[i]
if i < len(xlist) {
pos = xlist[i].Pos()
}
w.assign(pkg, pos, tpar, targs[i])
}

2
src/go/types/testdata/check/issues.go2 vendored
View File

@ -48,7 +48,7 @@ func (*T) m2()
func _() {
// TODO(rFindley) this error should be positioned on the 'T'.
f2 /* ERROR wrong method signature */ [T]()
f2[T /* ERROR wrong method signature */ ]()
f2[*T]()
}

5
src/go/types/testdata/fixedbugs/issue39754.go2 vendored
View File

@ -17,8 +17,5 @@ func f[V interface{}, A, B Box[V]]() {}
func _() {
f[int, Optional[int], Optional[int]]()
_ = f[int, Optional[int], Optional /* ERROR does not implement Box */ [string]]
// TODO(gri) Provide better position information here.
// See TODO in call.go, Checker.arguments.
// TODO(rFindley) Reconcile this error position with types2.
f /* ERROR does not implement Box */ [int, Optional[int], Optional[string]]()
_ = f[int, Optional[int], Optional /* ERROR Optional.* does not implement Box.* */ [string]]
}

19
src/go/types/testdata/fixedbugs/issue49179.go2 vendored Normal file
View File

@ -0,0 +1,19 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package p
type SliceConstraint[T any] interface {
[]T
}
func Map[S SliceConstraint[E], E any](s S, f func(E) E) S {
return s
}
type MySlice []int
func f(s MySlice) {
Map[MySlice /* ERROR MySlice does not implement SliceConstraint\[int\] */, int](s, nil)
}

13
src/go/types/typexpr.go
View File

@ -11,7 +11,6 @@ import (
"go/ast"
"go/constant"
"go/internal/typeparams"
"go/token"
"strings"
)
@ -416,12 +415,6 @@ func (check *Checker) instantiatedType(ix *typeparams.IndexExpr, def *Named) (re
return Typ[Invalid]
}
// determine argument positions
posList := make([]token.Pos, len(targs))
for i, arg := range ix.Indices {
posList[i] = arg.Pos()
}
// create the instance
ctxt := check.bestContext(nil)
h := ctxt.instanceHash(orig, targs)
@ -470,12 +463,12 @@ func (check *Checker) instantiatedType(ix *typeparams.IndexExpr, def *Named) (re
if i, err := check.verify(pos, inst.tparams.list(), inst.targs.list()); err != nil {
// best position for error reporting
pos := ix.Pos()
if i < len(posList) {
pos = posList[i]
if i < len(ix.Indices) {
pos = ix.Indices[i].Pos()
}
check.softErrorf(atPos(pos), _InvalidTypeArg, err.Error())
} else {
check.mono.recordInstance(check.pkg, pos, inst.tparams.list(), inst.targs.list(), posList)
check.mono.recordInstance(check.pkg, pos, inst.tparams.list(), inst.targs.list(), ix.Indices)
}
}