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cmd/cgo: don't ignore qualifiers, don't cast to void*

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The cgo tool used to simply ignore C type qualifiers. To avoid problems
when a C function expected a qualifier that was not present, cgo emitted
a cast to void* around all pointer arguments. Unfortunately, that broke
code that contains both a function declaration and a macro, when the
macro required the argument to have the right type. To fix this problem,
don't ignore qualifiers. They are easy enough to handle for the limited
set of cases that matter for cgo, in which we don't care about array or
function types.

Fixes #17537.

Change-Id: Ie2988d21db6ee016a3e99b07f53cfb0f1243a020
Reviewed-on: https://go-review.googlesource.com/33097
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Ian Lance Taylor 2016-11-10 14:34:32 -08:00
parent dc4a815d10
commit fb8c896aff
4 changed files with 53 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

10
src/cmd/cgo/gcc.go
View file

@ -1702,9 +1702,13 @@ func (c *typeConv) Type(dtype dwarf.Type, pos token.Pos) *Type {
c.ptrs[dt.Type] = append(c.ptrs[dt.Type], t)
case *dwarf.QualType:
// Ignore qualifier.
t = c.Type(dt.Type, pos)
c.m[dtype] = t
t1 := c.Type(dt.Type, pos)
t.Size = t1.Size
t.Align = t1.Align
t.Go = t1.Go
t.EnumValues = nil
t.Typedef = ""
t.C.Set("%s "+dt.Qual, t1.C)
return t
case *dwarf.StructType:

24
src/cmd/cgo/out.go
View file

@ -355,11 +355,7 @@ func (p *Package) structType(n *Name) (string, int64) {
fmt.Fprintf(&buf, "\t\tchar __pad%d[%d];\n", off, pad)
off += pad
}
qual := ""
if c := t.C.String(); c[len(c)-1] == '*' {
qual = "const "
}
fmt.Fprintf(&buf, "\t\t%s%s r;\n", qual, t.C)
fmt.Fprintf(&buf, "\t\t%s r;\n", t.C)
off += t.Size
}
if off%p.PtrSize != 0 {
@ -620,20 +616,10 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
}
}
fmt.Fprintf(fgcc, "%s(", n.C)
for i, t := range n.FuncType.Params {
for i := range n.FuncType.Params {
if i > 0 {
fmt.Fprintf(fgcc, ", ")
}
// We know the type params are correct, because
// the Go equivalents had good type params.
// However, our version of the type omits the magic
// words const and volatile, which can provoke
// C compiler warnings. Silence them by casting
// all pointers to void*. (Eventually that will produce
// other warnings.)
if c := t.C.String(); c[len(c)-1] == '*' {
fmt.Fprintf(fgcc, "(void*)")
}
fmt.Fprintf(fgcc, "a->p%d", i)
}
fmt.Fprintf(fgcc, ");\n")
@ -693,14 +679,10 @@ func (p *Package) writeGccgoOutputFunc(fgcc *os.File, n *Name) {
}
}
fmt.Fprintf(fgcc, "%s(", n.C)
for i, t := range n.FuncType.Params {
for i := range n.FuncType.Params {
if i > 0 {
fmt.Fprintf(fgcc, ", ")
}
// Cast to void* to avoid warnings due to omitted qualifiers.
if c := t.C.String(); c[len(c)-1] == '*' {
fmt.Fprintf(fgcc, "(void*)")
}
fmt.Fprintf(fgcc, "p%d", i)
}
fmt.Fprintf(fgcc, ");\n")