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go/parser: test and fix := scoping bug

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R=iant
CC=golang-dev, gri
https://golang.org/cl/5327048
This commit is contained in:
Russ Cox 2011-10-27 12:22:06 -07:00
parent d066e02adc
commit fd31d9fd7b
2 changed files with 53 additions and 1 deletions
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10
src/pkg/go/parser/parser.go
View file

@ -434,7 +434,9 @@ func (p *parser) parseLhsList() []ast.Expr {
switch p.tok {
case token.DEFINE:
// lhs of a short variable declaration
p.shortVarDecl(p.makeIdentList(list))
// but doesn't enter scope until later:
// caller must call p.shortVarDecl(p.makeIdentList(list))
// at appropriate time.
case token.COLON:
// lhs of a label declaration or a communication clause of a select
// statement (parseLhsList is not called when parsing the case clause
@ -1398,6 +1400,9 @@ func (p *parser) parseSimpleStmt(mode int) (ast.Stmt, bool) {
} else {
y = p.parseRhsList()
}
if tok == token.DEFINE {
p.shortVarDecl(p.makeIdentList(x))
}
return &ast.AssignStmt{x, pos, tok, y}, isRange
}
@ -1722,6 +1727,9 @@ func (p *parser) parseCommClause() *ast.CommClause {
}
p.next()
rhs = p.parseRhs()
if tok == token.DEFINE && lhs != nil {
p.shortVarDecl(p.makeIdentList(lhs))
}
} else {
// rhs must be single receive operation
if len(lhs) > 1 {

44
src/pkg/go/parser/parser_test.go
View file

@ -5,6 +5,7 @@
package parser
import (
"go/ast"
"go/token"
"os"
"testing"
@ -134,3 +135,46 @@ func TestParse4(t *testing.T) {
}
}
}
func TestColonEqualsScope(t *testing.T) {
f, err := ParseFile(fset, "", `package p; func f() { x, y, z := x, y, z }`, 0)
if err != nil {
t.Errorf("parse: %s", err)
}
// RHS refers to undefined globals; LHS does not.
as := f.Decls[0].(*ast.FuncDecl).Body.List[0].(*ast.AssignStmt)
for _, v := range as.Rhs {
id := v.(*ast.Ident)
if id.Obj != nil {
t.Errorf("rhs %s has Obj, should not", id.Name)
}
}
for _, v := range as.Lhs {
id := v.(*ast.Ident)
if id.Obj == nil {
t.Errorf("lhs %s does not have Obj, should", id.Name)
}
}
}
func TestVarScope(t *testing.T) {
f, err := ParseFile(fset, "", `package p; func f() { var x, y, z = x, y, z }`, 0)
if err != nil {
t.Errorf("parse: %s", err)
}
// RHS refers to undefined globals; LHS does not.
as := f.Decls[0].(*ast.FuncDecl).Body.List[0].(*ast.DeclStmt).Decl.(*ast.GenDecl).Specs[0].(*ast.ValueSpec)
for _, v := range as.Values {
id := v.(*ast.Ident)
if id.Obj != nil {
t.Errorf("rhs %s has Obj, should not", id.Name)
}
}
for _, id := range as.Names {
if id.Obj == nil {
t.Errorf("lhs %s does not have Obj, should", id.Name)
}
}
}