Rename function recv/params/results (#75)

This PR updates the compiler to rename function params, results and
receivers, so that the identifiers don't clash with those in the
generated code.

compiler/compile.go

@@ -372,12 +372,13 @@ func (scope *scope) compileFuncDecl(p *packages.Package, fn *ast.FuncDecl, color
 	// Generate the coroutine function. At this stage, use the same name
 	// as the source function (and require that the caller use build tags
 	// to disambiguate function calls).
+	fnType := funcTypeWithNamedResults(fn.Type)
 	gen := &ast.FuncDecl{
 		Recv: fn.Recv,
 		Doc:  &ast.CommentGroup{},
 		Name: fn.Name,
-		Type: funcTypeWithNamedResults(fn.Type),
-		Body: scope.compileFuncBody(p, fn.Type, fn.Body, fn.Recv, color),
+		Type: fnType,
+		Body: scope.compileFuncBody(p, fnType, fn.Body, fn.Recv, color),
 	}
 
 	// If the function declaration contains function literals, we have to
@@ -509,6 +510,8 @@ func (scope *scope) compileFuncBody(p *packages.Package, typ *ast.FuncType, body
 	frameName := ast.NewIdent(fmt.Sprintf("_f%d", scope.frameIndex))
 	scope.frameIndex++
 
+	renameFuncRecvParamsResults(typ, recv, body, p.TypesInfo)
+
 	// Handle declarations.
 	//
 	// Types, constants and variables can be defined within any scope in the

compiler/decls.go

@@ -5,6 +5,7 @@ import (
 	"go/ast"
 	"go/token"
 	"go/types"
+	"strconv"
 
 	"golang.org/x/tools/go/ast/astutil"
 	"golang.org/x/tools/go/packages"
@@ -317,3 +318,43 @@ func renameObjects(tree ast.Node, info *types.Info, decls []*ast.GenDecl, frameN
 		nil,
 	)
 }
+
+func renameFuncRecvParamsResults(typ *ast.FuncType, recv *ast.FieldList, body *ast.BlockStmt, info *types.Info) {
+	names := map[types.Object]*ast.Ident{}
+
+	fieldLists := []*ast.FieldList{recv, typ.Params, typ.Results}
+	for _, fieldList := range fieldLists {
+		if fieldList == nil {
+			continue
+		}
+		for _, field := range fieldList.List {
+			for _, name := range field.Names {
+				if name.Name == "_" {
+					continue
+				}
+				obj := info.ObjectOf(name)
+				newIdent := ast.NewIdent("_fn" + strconv.Itoa(len(names)))
+				names[obj] = newIdent
+				info.Defs[newIdent] = obj
+			}
+		}
+	}
+
+	decl := &ast.FuncDecl{
+		Recv: recv,
+		Type: typ,
+		Body: body,
+	}
+
+	astutil.Apply(decl, func(cursor *astutil.Cursor) bool {
+		switch n := cursor.Node().(type) {
+		case *ast.Ident:
+			if obj := info.ObjectOf(n); obj != nil {
+				if ident, ok := names[obj]; ok {
+					cursor.Replace(ident)
+				}
+			}
+		}
+		return true
+	}, nil)
+}