diff --git a/src/cmd/compile/internal/syntax/parser.go b/src/cmd/compile/internal/syntax/parser.go index e1cd8f9f5a1bb1de66c0d0f4db4d82efbe6b5967..d4e9bf2f9651540c4eed125c7ce69876209b6242 100644 --- a/src/cmd/compile/internal/syntax/parser.go +++ b/src/cmd/compile/internal/syntax/parser.go @@ -170,6 +170,20 @@ func (p *parser) want(tok token) { } } +// gotAssign is like got(_Assign) but it also accepts ":=" +// (and reports an error) for better parser error recovery. +func (p *parser) gotAssign() bool { + switch p.tok { + case _Define: + p.syntaxError("expecting =") + fallthrough + case _Assign: + p.next() + return true + } + return false +} + // ---------------------------------------------------------------------------- // Error handling @@ -514,7 +528,7 @@ func (p *parser) constDecl(group *Group) Decl { d.NameList = p.nameList(p.name()) if p.tok != _EOF && p.tok != _Semi && p.tok != _Rparen { d.Type = p.typeOrNil() - if p.got(_Assign) { + if p.gotAssign() { d.Values = p.exprList() } } @@ -533,7 +547,7 @@ func (p *parser) typeDecl(group *Group) Decl { d.pos = p.pos() d.Name = p.name() - d.Alias = p.got(_Assign) + d.Alias = p.gotAssign() d.Type = p.typeOrNil() if d.Type == nil { d.Type = p.bad() @@ -556,11 +570,11 @@ func (p *parser) varDecl(group *Group) Decl { d.pos = p.pos() d.NameList = p.nameList(p.name()) - if p.got(_Assign) { + if p.gotAssign() { d.Values = p.exprList() } else { d.Type = p.type_() - if p.got(_Assign) { + if p.gotAssign() { d.Values = p.exprList() } } diff --git a/src/cmd/compile/internal/syntax/testdata/issue31092.src b/src/cmd/compile/internal/syntax/testdata/issue31092.src new file mode 100644 index 0000000000000000000000000000000000000000..b1839b8f468290d97ff2cca2bec70401e402b7e7 --- /dev/null +++ b/src/cmd/compile/internal/syntax/testdata/issue31092.src @@ -0,0 +1,16 @@ +// Copyright 2018 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. + +// Test cases for issue 31092: Better synchronization of +// parser after seeing an := rather than an = in a const, +// type, or variable declaration. + +package p + +const _ /* ERROR unexpected := */ := 0 +type _ /* ERROR unexpected := */ := int +var _ /* ERROR unexpected := */ := 0 + +const _ int /* ERROR unexpected := */ := 0 +var _ int /* ERROR unexpected := */ := 0