cmd/cgo: fix C.complexfloat and C.complexdouble

This also fixes an unintended behavior where C's "complex float" and
"complex double" types were interchangeable with Go's "complex64" and
"complex128" types.

Fixes #13402.

Change-Id: I73f96d9a4772088d495073783c6982e9634430e8
Reviewed-on: https://go-review.googlesource.com/17208Reviewed-by: Ian Lance Taylor <iant@golang.org>

misc/cgo/test/issue13402.go

+// Copyright 2015 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.
+
+package cgotest
+
+import "C"
+
+var _ C.complexfloat
+var _ C.complexdouble

misc/cgo/test/issue8694.go

@@ -22,14 +22,14 @@ func test8694(t *testing.T) {
 		t.Skip("test8694 is disabled on ARM because 5l cannot handle thumb library.")
 	}
 	// Really just testing that this compiles, but check answer anyway.
-	x := complex64(2 + 3i)
+	x := C.complexfloat(2 + 3i)
 	x2 := x * x
 	cx2 := C.complexFloatSquared(x)
 	if cx2 != x2 {
 		t.Errorf("C.complexFloatSquared(%v) = %v, want %v", x, cx2, x2)
 	}
 
-	y := complex128(2 + 3i)
+	y := C.complexdouble(2 + 3i)
 	y2 := y * y
 	cy2 := C.complexDoubleSquared(y)
 	if cy2 != y2 {

src/cmd/cgo/doc.go

@@ -117,7 +117,8 @@ The standard C numeric types are available under the names
 C.char, C.schar (signed char), C.uchar (unsigned char),
 C.short, C.ushort (unsigned short), C.int, C.uint (unsigned int),
 C.long, C.ulong (unsigned long), C.longlong (long long),
-C.ulonglong (unsigned long long), C.float, C.double.
+C.ulonglong (unsigned long long), C.float, C.double,
+C.complexfloat (complex float), and C.complexdouble (complex double).
 The C type void* is represented by Go's unsafe.Pointer.
 The C types __int128_t and __uint128_t are represented by [16]byte.
 

src/cmd/cgo/gcc.go

@@ -38,8 +38,8 @@ var nameToC = map[string]string{
 	"ulong":         "unsigned long",
 	"longlong":      "long long",
 	"ulonglong":     "unsigned long long",
-	"complexfloat":  "float complex",
-	"complexdouble": "double complex",
+	"complexfloat":  "__complex float",
+	"complexdouble": "__complex double",
 }
 
 // cname returns the C name to use for C.s.
@@ -1319,8 +1319,6 @@ var dwarfToName = map[string]string{
 	"long long int":          "longlong",
 	"long long unsigned int": "ulonglong",
 	"signed char":            "schar",
-	"float complex":          "complexfloat",
-	"double complex":         "complexdouble",
 }
 
 const signedDelta = 64
@@ -1690,7 +1688,7 @@ func (c *typeConv) Type(dtype dwarf.Type, pos token.Pos) *Type {
 	}
 
 	switch dtype.(type) {
-	case *dwarf.AddrType, *dwarf.BoolType, *dwarf.CharType, *dwarf.IntType, *dwarf.FloatType, *dwarf.UcharType, *dwarf.UintType:
+	case *dwarf.AddrType, *dwarf.BoolType, *dwarf.CharType, *dwarf.ComplexType, *dwarf.IntType, *dwarf.FloatType, *dwarf.UcharType, *dwarf.UintType:
 		s := dtype.Common().Name
 		if s != "" {
 			if ss, ok := dwarfToName[s]; ok {