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| author | Robert Griesemer <gri@golang.org> | 2024-05-23 14:40:22 -0700 |
|---|---|---|
| committer | Robert Griesemer <gri@google.com> | 2024-05-23 23:17:08 +0000 |
| commit | 2fe2e4d593aaa01ca00ad861808846a2b3328b05 (patch) | |
| tree | eb63e58bc0dbf5f20e9050764acd4bb5bcea4e5d | |
| parent | 13e3068b9c0f8640207b1497d15b730b8e31bb51 (diff) | |
| download | go-2fe2e4d593aaa01ca00ad861808846a2b3328b05.tar.xz | |
go/types, types2: document why Unalias is not needed in some places
Documentation change only.
For #67547.
Change-Id: I0da480299c33239bcd1e059f8b9c6d48d8f26609
Reviewed-on: https://go-review.googlesource.com/c/go/+/587820
TryBot-Bypass: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
| -rw-r--r-- | src/cmd/compile/internal/types2/infer.go | 6 | ||||
| -rw-r--r-- | src/go/types/infer.go | 6 |
2 files changed, 10 insertions, 2 deletions
diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go index 1cdc4e79a2..2a46de9b97 100644 --- a/src/cmd/compile/internal/types2/infer.go +++ b/src/cmd/compile/internal/types2/infer.go @@ -184,6 +184,10 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeParam, targs []Type, // Thus, for untyped arguments we only need to look at parameter types // that are single type parameters. // Also, untyped nils don't have a default type and can be ignored. + // Finally, it's not possible to have an alias type denoting a type + // parameter declared by the current function and use it in the same + // function signature; hence we don't need to Unalias before the + // .(*TypeParam) type assertion above. untyped = append(untyped, i) } } @@ -306,7 +310,7 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeParam, targs []Type, // maximum untyped type for each of those parameters, if possible. var maxUntyped map[*TypeParam]Type // lazily allocated (we may not need it) for _, index := range untyped { - tpar := params.At(index).typ.(*TypeParam) // is type parameter by construction of untyped + tpar := params.At(index).typ.(*TypeParam) // is type parameter (no alias) by construction of untyped if u.at(tpar) == nil { arg := args[index] // arg corresponding to tpar if maxUntyped == nil { diff --git a/src/go/types/infer.go b/src/go/types/infer.go index 76c3c72a1a..7e63b0a665 100644 --- a/src/go/types/infer.go +++ b/src/go/types/infer.go @@ -187,6 +187,10 @@ func (check *Checker) infer(posn positioner, tparams []*TypeParam, targs []Type, // Thus, for untyped arguments we only need to look at parameter types // that are single type parameters. // Also, untyped nils don't have a default type and can be ignored. + // Finally, it's not possible to have an alias type denoting a type + // parameter declared by the current function and use it in the same + // function signature; hence we don't need to Unalias before the + // .(*TypeParam) type assertion above. untyped = append(untyped, i) } } @@ -309,7 +313,7 @@ func (check *Checker) infer(posn positioner, tparams []*TypeParam, targs []Type, // maximum untyped type for each of those parameters, if possible. var maxUntyped map[*TypeParam]Type // lazily allocated (we may not need it) for _, index := range untyped { - tpar := params.At(index).typ.(*TypeParam) // is type parameter by construction of untyped + tpar := params.At(index).typ.(*TypeParam) // is type parameter (no alias) by construction of untyped if u.at(tpar) == nil { arg := args[index] // arg corresponding to tpar if maxUntyped == nil { |