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[dev.typeparams] cmd/compile/internal/types2: no "declared but not used" errors for invalid var decls

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Matches compiler behavior.

Change-Id: I87ca46fb7269fbac61ffbf8ed48902156b06f6e4
Reviewed-on: https://go-review.googlesource.com/c/go/+/274615
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2020-12-01 16:02:37 -08:00
parent 036245862a
commit ab18125567
3 changed files with 27 additions and 1 deletions
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1
src/cmd/compile/internal/types2/assignments.go
View File

@ -112,6 +112,7 @@ func (check *Checker) initVar(lhs *Var, x *operand, context string) Type {
if lhs.typ == nil {
lhs.typ = Typ[Invalid]
}
lhs.used = true // avoid follow-on "declared but not used" errors
return nil
}

14
src/cmd/compile/internal/types2/decl.go
View File

@ -457,6 +457,20 @@ func (check *Checker) constDecl(obj *Const, typ, init syntax.Expr) {
func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init syntax.Expr) {
assert(obj.typ == nil)
// If we have undefined variable types due to errors,
// mark variables as used to avoid follow-on errors.
// Matches compiler behavior.
defer func() {
if obj.typ == Typ[Invalid] {
obj.used = true
}
for _, lhs := range lhs {
if lhs.typ == Typ[Invalid] {
lhs.used = true
}
}
}()
// determine type, if any
if typ != nil {
obj.typ = check.varType(typ)

13
src/cmd/compile/internal/types2/testdata/vardecl.src vendored
View File

@ -155,7 +155,18 @@ func _() {
}
}
// Invalid (unused) expressions must not lead to spurious "declared but not used errors"
// Invalid variable declarations must not lead to "declared but not used errors".
func _() {
var a x // ERROR undeclared name: x
var b = x // ERROR undeclared name: x
var c int = x // ERROR undeclared name: x
var d, e, f x /* ERROR x */ /* ERROR x */ /* ERROR x */
var g, h, i = x, x, x /* ERROR x */ /* ERROR x */ /* ERROR x */
var j, k, l float32 = x, x, x /* ERROR x */ /* ERROR x */ /* ERROR x */
// but no "declared but not used" errors
}
// Invalid (unused) expressions must not lead to spurious "declared but not used errors".
func _() {
var a, b, c int
var x, y int