Use the object's package to mangle method names, rather than the receiver's package

pcc · pcc · commit 545e7276a870 · 2014-12-16T20:04:55.000Z
If we use the receiver's package, we can end up with identical manglings for different functions. Consider: package p type U struct{} func (U) f() package q import "p" type T struct { p.U } func (T) f() The method set of *T has two synthetic methods named (*T).f(); one forwards to (T).f(), and the other to (U).f(). Previously, we were distinguishing them by the receiver's package, and in this case because both methods have the same receiver, they received the same name. The methods are correctly distinguished by the package owning the identifier "f", which is available via f.Object().Pkg(). Differential Revision: http://reviews.llvm.org/D6673 llvm-svn: 224357
diff --git a/llgo/irgen/typemap.go b/llgo/irgen/typemap.go
@@ -659,21 +659,25 @@ func (ctx *manglerContext) mangleFunctionName(f *ssa.Function) string {
 		return b.String()
 	}
 
-	pkg := f.Pkg
-	var pkgobj *types.Package
-	if pkg != nil {
-		pkgobj = pkg.Object
-	} else if f.Signature.Recv() != nil {
-		pkgobj = f.Signature.Recv().Pkg()
-	} else {
+	// Synthetic bound and thunk functions are special cases; they can only be
+	// distinguished using private data that is only exposed via String().
+	if strings.HasSuffix(f.Name(), "$bound") || strings.HasSuffix(f.Name(), "$thunk") {
 		b.WriteString(f.String())
 		return b.String()
 	}
 
+	var pkg *types.Package
+	if f.Pkg != nil {
+		pkg = f.Pkg.Object
+	} else if !f.Object().Exported() {
+		pkg = f.Object().Pkg()
+	}
+
 	if pkg != nil {
-		ctx.manglePackagePath(pkgobj.Path(), &b)
+		ctx.manglePackagePath(pkg.Path(), &b)
 		b.WriteRune('.')
 	}
+
 	if f.Signature.Recv() == nil && f.Name() == "init" {
 		b.WriteString(".import")
 	} else {
diff --git a/llgo/test/irgen/Inputs/mangling-synthetic-p.go b/llgo/test/irgen/Inputs/mangling-synthetic-p.go
@@ -0,0 +1,4 @@
+package p
+
+type U struct{}
+func (U) f()
diff --git a/llgo/test/irgen/mangling-dot.go b/llgo/test/irgen/mangling-dot.go
diff --git a/llgo/test/irgen/mangling-synthetic.go b/llgo/test/irgen/mangling-synthetic.go
@@ -0,0 +1,14 @@
+// RUN: llgo -fgo-pkgpath=p -c -o %T/p.o %S/Inputs/mangling-synthetic-p.go
+// RUN: llgo -fgo-pkgpath=q -I %T -S -emit-llvm -o - %s | FileCheck %s
+
+package q
+
+import "p"
+
+// CHECK-DAG: define linkonce_odr void @p.f.N3_q.T(i8*)
+// CHECK-DAG: define linkonce_odr void @p.f.pN3_q.T(i8*)
+type T struct { p.U }
+
+// CHECK-DAG: declare void @q.f.N3_q.T(i8*)
+// CHECK-DAG: define linkonce_odr void @q.f.pN3_q.T(i8*)
+func (T) f()
