cmd/cgo: split name rewriting out of rewriteRef

This is in preparation for later changes.

Change-Id: I2b9b77a782cf65a2fcec5e700ec6bb8b1476f6b5
Reviewed-on: https://go-review.googlesource.com/c/142882
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/cgo/gcc.go

@@ -1166,6 +1166,60 @@ func (p *Package) rewriteRef(f *File) {
 		if r.Name.IsConst() && r.Name.Const == "" {
 			error_(r.Pos(), "unable to find value of constant C.%s", fixGo(r.Name.Go))
 		}
+
+		if r.Name.Kind == "func" {
+			switch r.Context {
+			case ctxCall, ctxCall2:
+				functions[r.Name.Go] = true
+			}
+		}
+
+		expr := p.rewriteName(f, r)
+
+		if *godefs {
+			// Substitute definition for mangled type name.
+			if id, ok := expr.(*ast.Ident); ok {
+				if t := typedef[id.Name]; t != nil {
+					expr = t.Go
+				}
+				if id.Name == r.Name.Mangle && r.Name.Const != "" {
+					expr = ast.NewIdent(r.Name.Const)
+				}
+			}
+		}
+
+		// Copy position information from old expr into new expr,
+		// in case expression being replaced is first on line.
+		// See golang.org/issue/6563.
+		pos := (*r.Expr).Pos()
+		if x, ok := expr.(*ast.Ident); ok {
+			expr = &ast.Ident{NamePos: pos, Name: x.Name}
+		}
+
+		// Change AST, because some later processing depends on it,
+		// and also because -godefs mode still prints the AST.
+		old := *r.Expr
+		*r.Expr = expr
+
+		// Record source-level edit for cgo output.
+		repl := gofmt(expr)
+		if r.Name.Kind != "type" {
+			repl = "(" + repl + ")"
+		}
+		f.Edit.Replace(f.offset(old.Pos()), f.offset(old.End()), repl)
+	}
+
+	// Remove functions only used as expressions, so their respective
+	// bridge functions are not generated.
+	for name, used := range functions {
+		if !used {
+			delete(f.Name, name)
+		}
+	}
+}
+
+// rewriteName returns the expression used to rewrite a reference.
+func (p *Package) rewriteName(f *File, r *Ref) ast.Expr {
 	var expr ast.Expr = ast.NewIdent(r.Name.Mangle) // default
 	switch r.Context {
 	case ctxCall, ctxCall2:
@@ -1182,7 +1236,6 @@ func (p *Package) rewriteRef(f *File) {
 			error_(r.Pos(), "call of non-function C.%s", fixGo(r.Name.Go))
 			break
 		}
-			functions[r.Name.Go] = true
 		if r.Context == ctxCall2 {
 			if r.Name.Go == "_CMalloc" {
 				error_(r.Pos(), "no two-result form for C.malloc")
@@ -1263,47 +1316,7 @@ func (p *Package) rewriteRef(f *File) {
 			error_(r.Pos(), "must call C.%s", fixGo(r.Name.Go))
 		}
 	}
-
+	return expr
-		if *godefs {
-			// Substitute definition for mangled type name.
-			if id, ok := expr.(*ast.Ident); ok {
-				if t := typedef[id.Name]; t != nil {
-					expr = t.Go
-				}
-				if id.Name == r.Name.Mangle && r.Name.Const != "" {
-					expr = ast.NewIdent(r.Name.Const)
-				}
-			}
-		}
-
-		// Copy position information from old expr into new expr,
-		// in case expression being replaced is first on line.
-		// See golang.org/issue/6563.
-		pos := (*r.Expr).Pos()
-		if x, ok := expr.(*ast.Ident); ok {
-			expr = &ast.Ident{NamePos: pos, Name: x.Name}
-		}
-
-		// Change AST, because some later processing depends on it,
-		// and also because -godefs mode still prints the AST.
-		old := *r.Expr
-		*r.Expr = expr
-
-		// Record source-level edit for cgo output.
-		repl := gofmt(expr)
-		if r.Name.Kind != "type" {
-			repl = "(" + repl + ")"
-		}
-		f.Edit.Replace(f.offset(old.Pos()), f.offset(old.End()), repl)
-	}
-
-	// Remove functions only used as expressions, so their respective
-	// bridge functions are not generated.
-	for name, used := range functions {
-		if !used {
-			delete(f.Name, name)
-		}
-	}
 }
 
 // gccBaseCmd returns the start of the compiler command line.