cmd/gc: add space to export data to match linker expectations

The linker split PKGDEF into (prefix, name, def) pairs,
and defines def to begin after a space following the identifier.
This is totally wrong for the following export data:

        func "".FunctionName()
        var SomethingCompletelyUnrelated int

The linker would parse
    name=`"".FunctionName()\n\tvar`
    def=`SomethingCompletelyUnrelated int`
since there is no space after FunctionName.

R=minux.ma, rsc
CC=golang-dev
https://golang.org/cl/7068051

src/cmd/gc/export.c

@@ -220,10 +220,11 @@ dumpexportvar(Sym *s)
 			// currently that can leave unresolved ONONAMEs in import-dot-ed packages in the wrong package
 			if(debug['l'] < 2)
 				typecheckinl(n);
-			Bprint(bout, "\tfunc %#S%#hT { %#H }\n", s, t, n->inl);
+			// NOTE: The space after %#S here is necessary for ld's export data parser.
+			Bprint(bout, "\tfunc %#S %#hT { %#H }\n", s, t, n->inl);
 			reexportdeplist(n->inl);
 		} else
-			Bprint(bout, "\tfunc %#S%#hT\n", s, t);
+			Bprint(bout, "\tfunc %#S %#hT\n", s, t);
 	} else
 		Bprint(bout, "\tvar %#S %#T\n", s, t);
 }
@@ -282,10 +283,10 @@ dumpexporttype(Type *t)
 			// currently that can leave unresolved ONONAMEs in import-dot-ed packages in the wrong package
 			if(debug['l'] < 2)
 				typecheckinl(f->type->nname);
-			Bprint(bout, "\tfunc (%#T) %#hhS%#hT { %#H }\n", getthisx(f->type)->type, f->sym, f->type, f->type->nname->inl);
+			Bprint(bout, "\tfunc (%#T) %#hhS %#hT { %#H }\n", getthisx(f->type)->type, f->sym, f->type, f->type->nname->inl);
 			reexportdeplist(f->type->nname->inl);
 		} else
-			Bprint(bout, "\tfunc (%#T) %#hhS%#hT\n", getthisx(f->type)->type, f->sym, f->type);
+			Bprint(bout, "\tfunc (%#T) %#hhS %#hT\n", getthisx(f->type)->type, f->sym, f->type);
 	}
 }
 

test/fixedbugs/bug472.dir/p1.go

+// Copyright 2013 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 p1
+
+import "runtime"
+
+func E() func() int { return runtime.NumCPU }
+
+func F() func() { return runtime.Gosched }
+
+func G() func() string { return runtime.GOROOT }
+
+func H() func() { return runtime.GC }
+
+func I() func() string { return runtime.Version }

test/fixedbugs/bug472.dir/p2.go

+// Copyright 2013 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 p2
+
+import "runtime"
+
+func E() func() int { return runtime.NumCPU }
+
+func F() func() { return runtime.GC }
+
+func G() func() string { return runtime.GOROOT }
+
+func H() func() { return runtime.Gosched }
+
+func I() func() string { return runtime.Version }

test/fixedbugs/bug472.dir/z.go

+// Copyright 2013 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 main
+
+import (
+	_ "./p1"
+	_ "./p2"
+)
+
+func main() {
+}

test/fixedbugs/bug472.go

+// rundir
+
+// Copyright 2013 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.
+
+// Linker would incorrectly parse export data and think
+// definitions are inconsistent.
+
+package ignored