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| author | Robert Griesemer <gri@golang.org> | 2022-01-06 14:10:45 -0800 |
|---|---|---|
| committer | Robert Griesemer <gri@golang.org> | 2022-01-07 00:02:57 +0000 |
| commit | c295137ad8e5e947205d060a26164cb71952c1bb (patch) | |
| tree | d5fe6f4e2c564162076acc3784b0bc7ab8bba8d3 /src | |
| parent | 042548b1fdba21e351368e9f3ecd93059d09083f (diff) | |
| download | go-c295137ad8e5e947205d060a26164cb71952c1bb.tar.gz go-c295137ad8e5e947205d060a26164cb71952c1bb.zip | |
go/types, types2: disallow multiple blank type parameters
Work-around for #50481: report an error for multiple
blank type parameters. It's always possible to use
non-blank names in those cases.
We expect to lift this restriction for 1.19.
For #50481.
Change-Id: Ifdd2d91340aac1da3387f7d80d46e44f5997c2a8
Reviewed-on: https://go-review.googlesource.com/c/go/+/376058
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
Trust: Dan Scales <danscales@google.com>
Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/types2/decl.go | 11 | ||||
| -rw-r--r-- | src/go/types/decl.go | 13 |
2 files changed, 24 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/types2/decl.go b/src/cmd/compile/internal/types2/decl.go index d61d2a8b0d..69388f78be 100644 --- a/src/cmd/compile/internal/types2/decl.go +++ b/src/cmd/compile/internal/types2/decl.go @@ -632,8 +632,19 @@ func (check *Checker) collectTypeParams(dst **TypeParamList, list []*syntax.Fiel // Declare type parameters up-front. // The scope of type parameters starts at the beginning of the type parameter // list (so we can have mutually recursive parameterized type bounds). + nblanks := 0 for i, f := range list { tparams[i] = check.declareTypeParam(f.Name) + // Issue #50481: For now, disallow multiple blank type parameters because + // it causes problems with export data. Report an error unless we are in + // testing mode ("assert" is defined). + // We expect to lift this restriction for Go 1.19. + if f.Name.Value == "_" { + nblanks++ + if nblanks == 2 && Universe.Lookup("assert") == nil { + check.softErrorf(f, "cannot have multiple blank type parameters (temporary restriction, see issue #50481)") + } + } } // Set the type parameters before collecting the type constraints because diff --git a/src/go/types/decl.go b/src/go/types/decl.go index 02af0d5f3e..bbd3f04b7e 100644 --- a/src/go/types/decl.go +++ b/src/go/types/decl.go @@ -684,8 +684,21 @@ func (check *Checker) collectTypeParams(dst **TypeParamList, list *ast.FieldList // Declare type parameters up-front, with empty interface as type bound. // The scope of type parameters starts at the beginning of the type parameter // list (so we can have mutually recursive parameterized interfaces). + nblanks := 0 for _, f := range list.List { tparams = check.declareTypeParams(tparams, f.Names) + // Issue #50481: For now, disallow multiple blank type parameters because + // it causes problems with export data. Report an error unless we are in + // testing mode ("assert" is defined). + // We expect to lift this restriction for Go 1.19. + for _, name := range f.Names { + if name.Name == "_" { + nblanks++ + if nblanks == 2 && Universe.Lookup("assert") == nil { + check.softErrorf(name, _InvalidBlank, "cannot have multiple blank type parameters (temporary restriction, see issue #50481)") + } + } + } } // Set the type parameters before collecting the type constraints because |