From 599de4b2c348738a5d6d2f5d475c74ac835e091a Mon Sep 17 00:00:00 2001 From: Robert Griesemer Date: Mon, 1 Nov 2021 13:41:32 -0700 Subject: [PATCH] cmd/compile/internal/types2: adjust printing of type parameter in error For constraint type inference failures where the type parameter doesn't match the constraint, print the type parameter rather than its type name object. This provides more flexibility for improving the error message down the road. Change-Id: I188871d6f26a16cd96e59770966a1ec65607b128 Reviewed-on: https://go-review.googlesource.com/c/go/+/360514 Trust: Robert Griesemer Reviewed-by: Robert Findley --- src/cmd/compile/internal/types2/infer.go | 7 ++++--- .../internal/types2/testdata/fixedbugs/issue45985.go2 | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go index 494e896ee97..24c461f1c36 100644 --- a/src/cmd/compile/internal/types2/infer.go +++ b/src/cmd/compile/internal/types2/infer.go @@ -378,7 +378,6 @@ func (check *Checker) inferB(tparams []*TypeParam, targs []Type) (types []Type, // If a constraint has a structural type, unify the corresponding type parameter with it. for _, tpar := range tparams { - typ := tpar sbound := structure(tpar) if sbound != nil { // If the structural type is the underlying type of a single @@ -386,8 +385,10 @@ func (check *Checker) inferB(tparams []*TypeParam, targs []Type) (types []Type, if named, _ := tpar.singleType().(*Named); named != nil { sbound = named } - if !u.unify(typ, sbound) { - check.errorf(tpar.obj, "%s does not match %s", tpar.obj, sbound) + if !u.unify(tpar, sbound) { + // TODO(gri) improve error message by providing the type arguments + // which we know already + check.errorf(tpar.obj, "%s does not match %s", tpar, sbound) return nil, 0 } } diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2 index ee5282d6ef3..9963d2ee003 100644 --- a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2 +++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue45985.go2 @@ -5,7 +5,7 @@ package issue45985 // TODO(gri): this error should be on app[int] below. -func app[S /* ERROR "type S S does not match" */ interface{ ~[]T }, T any](s S, e T) S { +func app[S /* ERROR "S does not match" */ interface{ ~[]T }, T any](s S, e T) S { return append(s, e) }