cmd/compile: remove Pointer from builtin/unsafe.go

We already explicitly construct the "unsafe.Pointer" type in typeinit
because we need it for Types[TUNSAFEPTR]. No point in also having it
in builtin/unsafe.go if it just means (*importer).importtype needs to
fix it.

Change-Id: Ife8a5a73cbbe2bfcabe8b25ee4f7e0f5fd0570b4
Reviewed-on: https://go-review.googlesource.com/29082
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/gc/bimport.go

@@ -390,13 +390,6 @@ func (p *importer) newtyp(etype EType) *Type {
 
 // importtype declares that pt, an imported named type, has underlying type t.
 func (p *importer) importtype(pt, t *Type) {
-	// override declaration in unsafe.go for Pointer.
-	// there is no way in Go code to define unsafe.Pointer
-	// so we have to supply it.
-	if incannedimport != 0 && importpkg.Name == "unsafe" && pt.Nod.Sym.Name == "Pointer" {
-		t = Types[TUNSAFEPTR]
-	}
-
 	if pt.Etype == TFORW {
 		n := pt.Nod
 		copytype(pt.Nod, t)

src/cmd/compile/internal/gc/builtin.go

@@ -106,6 +106,5 @@ const runtimeimport = "" +
 	"\x11msanwrite\x00\x04\x16\x96\x03\x00`\x16\x98\x03\x00`\x00\v\xf8\x01\v\x00\x01\x00\n$$\n"
 
 const unsafeimport = "" +
-	"version 2\n\n\x00\x00\x01\vunsafe\x00\x05\r\rPointer\x00\x16\x00\t\x0fOff" +
-	"setof\x00\x01:\x00\x01\x16\x00\t\vSizeof\x00\x01:\x00\x01\x16\x00\t\rAlignof\x00\x01:\x00" +
-	"\x01\x16\x00\v\b\v\x00\x01\x00\n$$\n"
+	"version 2\n\n\x00\x00\x01\vunsafe\x00\t\x0fOffsetof\x00\x01:\x00\x01\x16\x00\t" +
+	"\vSizeof\x00\x01:\x00\x01\x16\x00\t\rAlignof\x00\x01:\x00\x01\x16\x00\v\x06\v\x00\x01\x00\n$$\n"

src/cmd/compile/internal/gc/builtin/unsafe.go

@@ -10,7 +10,7 @@
 
 package unsafe
 
-type Pointer uintptr // not really; filled in by compiler
+// Type Pointer is constructed directly in typeinit.
 
 // return types here are ignored; see unsafe.go
 func Offsetof(any) uintptr

src/cmd/compile/internal/gc/universe.go

@@ -163,7 +163,6 @@ func typeinit() {
 	t.Sym = Pkglookup("Pointer", unsafepkg)
 	t.Sym.Def = typenod(t)
 	t.Sym.Def.Name = new(Name)
-
 	dowidth(Types[TUNSAFEPTR])
 
 	Tptr = TPTR32