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cmd/cgo: ignore top-level qualifiers in function args/results

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The top-level qualifiers are unimportant for our purposes. If a C
function is defined as `const int f(const int i)`, the `const`s are
meaningless to C, and we want to avoid using them in the struct we
create where the `const` has a completely different meaning.

This unwinds https://golang.org/cl/33097 with regard to top-level
qualifiers.

Change-Id: I3d66b0eb43b6d9a586d9cdedfae5a2306b46d96c
Reviewed-on: https://go-review.googlesource.com/33325
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
This commit is contained in:
Ian Lance Taylor 2016-11-16 09:55:24 -08:00
parent c1e9760d4c
commit 7061dc3f6e
2 changed files with 16 additions and 3 deletions
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2
misc/cgo/test/issue17537.go
View file

@ -20,7 +20,7 @@ int I17537(S17537 *p);
#define I17537(p) ((p)->i) #define I17537(p) ((p)->i)
// Calling this function used to fail without the cast. // Calling this function used to fail without the cast.
int F17537(const char **p) { const int F17537(const char **p) {
return **p; return **p;
} }
*/ */

17
src/cmd/cgo/gcc.go
View file

@ -1476,6 +1476,19 @@ func base(dt dwarf.Type) dwarf.Type {
return dt return dt
} }
// unqual strips away qualifiers from a DWARF type.
// In general we don't care about top-level qualifiers.
func unqual(dt dwarf.Type) dwarf.Type {
for {
if d, ok := dt.(*dwarf.QualType); ok {
dt = d.Type
} else {
break
}
}
return dt
}
// Map from dwarf text names to aliases we use in package "C". // Map from dwarf text names to aliases we use in package "C".
var dwarfToName = map[string]string{ var dwarfToName = map[string]string{
"long int": "long", "long int": "long",
@ -1930,7 +1943,7 @@ func isStructUnionClass(x ast.Expr) bool {
// FuncArg returns a Go type with the same memory layout as // FuncArg returns a Go type with the same memory layout as
// dtype when used as the type of a C function argument. // dtype when used as the type of a C function argument.
func (c *typeConv) FuncArg(dtype dwarf.Type, pos token.Pos) *Type { func (c *typeConv) FuncArg(dtype dwarf.Type, pos token.Pos) *Type {
t := c.Type(dtype, pos) t := c.Type(unqual(dtype), pos)
switch dt := dtype.(type) { switch dt := dtype.(type) {
case *dwarf.ArrayType: case *dwarf.ArrayType:
// Arrays are passed implicitly as pointers in C. // Arrays are passed implicitly as pointers in C.
@ -1994,7 +2007,7 @@ func (c *typeConv) FuncType(dtype *dwarf.FuncType, pos token.Pos) *FuncType {
if _, ok := dtype.ReturnType.(*dwarf.VoidType); ok { if _, ok := dtype.ReturnType.(*dwarf.VoidType); ok {
gr = []*ast.Field{{Type: c.goVoid}} gr = []*ast.Field{{Type: c.goVoid}}
} else if dtype.ReturnType != nil { } else if dtype.ReturnType != nil {
r = c.Type(dtype.ReturnType, pos) r = c.Type(unqual(dtype.ReturnType), pos)
gr = []*ast.Field{{Type: r.Go}} gr = []*ast.Field{{Type: r.Go}}
} }
return &FuncType{ return &FuncType{