From 6f8e8e14c8c860b7da2c3d97a7c92c4bd57e503b Mon Sep 17 00:00:00 2001
From: Rebecca Stambler <rstambler@golang.org>
Date: Thu, 12 Jul 2018 12:52:18 -0400
Subject: [PATCH] go/types: record type information after detecting error

The existing implementation stops recording type information once it
encounters an error. This results in missing type information that is
needed by various tools. This change handles a few commonly encountered
cases by continuing to check subtrees after errors. Also, add tests for
cases where the package fails to type-check.

Updates #22467

Change-Id: I1bb48d4cb8ae5548dca63bdd785ea2f69329e92b
Reviewed-on: https://go-review.googlesource.com/123578
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>
---
 src/go/types/api_test.go    | 22 ++++++++++++++++++++--
 src/go/types/assignments.go |  1 +
 src/go/types/call.go        |  3 +++
 src/go/types/expr.go        |  6 +++---
 4 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index 1d3c32520a..700fde9231 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -26,7 +26,6 @@ func pkgFor(path, source string, info *Info) (*Package, error) {
 	if err != nil {
 		return nil, err
 	}
-
 	conf := Config{Importer: importer.Default()}
 	return conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
 }
@@ -43,6 +42,20 @@ func mustTypecheck(t *testing.T, path, source string, info *Info) string {
 	return pkg.Name()
 }
 
+func maybeTypecheck(t *testing.T, path, source string, info *Info) string {
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, path, source, 0)
+	if f == nil { // ignore errors unless f is nil
+		t.Fatalf("%s: unable to parse: %s", path, err)
+	}
+	conf := Config{
+		Error:    func(err error) {},
+		Importer: importer.Default(),
+	}
+	pkg, _ := conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
+	return pkg.Name()
+}
+
 func TestValuesInfo(t *testing.T) {
 	var tests = []struct {
 		src  string
@@ -243,11 +256,16 @@ func TestTypesInfo(t *testing.T) {
 			`<-ch`,
 			`(string, bool)`,
 		},
+
+		// tests for broken code that doesn't parse or type-check
+		{`package x0; func _() { var x struct {f string}; x.f := 0 }`, `x.f`, `string`},
+		{`package x1; func _() { var z string; type x struct {f string}; y := &x{q: z}}`, `z`, `string`},
+		{`package x2; func _() { var a, b string; type x struct {f string}; z := &x{f: a; f: b;}}`, `b`, `string`},
 	}
 
 	for _, test := range tests {
 		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
-		name := mustTypecheck(t, "TypesInfo", test.src, &info)
+		name := maybeTypecheck(t, "TypesInfo", test.src, &info)
 
 		// look for expression type
 		var typ Type
diff --git a/src/go/types/assignments.go b/src/go/types/assignments.go
index cb0fe3bc3a..6adef3b407 100644
--- a/src/go/types/assignments.go
+++ b/src/go/types/assignments.go
@@ -310,6 +310,7 @@ func (check *Checker) shortVarDecl(pos token.Pos, lhs, rhs []ast.Expr) {
 				check.recordDef(ident, obj)
 			}
 		} else {
+			check.expr(&operand{}, lhs)
 			check.errorf(lhs.Pos(), "cannot declare %s", lhs)
 		}
 		if obj == nil {
diff --git a/src/go/types/call.go b/src/go/types/call.go
index 1b40651b73..4e8544ad88 100644
--- a/src/go/types/call.go
+++ b/src/go/types/call.go
@@ -34,6 +34,9 @@ func (check *Checker) call(x *operand, e *ast.CallExpr) exprKind {
 				check.conversion(x, T)
 			}
 		default:
+			for _, arg := range e.Args {
+				check.expr(&operand{}, arg)
+			}
 			check.errorf(e.Args[n-1].Pos(), "too many arguments in conversion to %s", T)
 		}
 		x.expr = e
diff --git a/src/go/types/expr.go b/src/go/types/expr.go
index 39ee6bcca3..60ac4a33ad 100644
--- a/src/go/types/expr.go
+++ b/src/go/types/expr.go
@@ -1094,6 +1094,7 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 						continue
 					}
 					key, _ := kv.Key.(*ast.Ident)
+					check.expr(x, kv.Value)
 					if key == nil {
 						check.errorf(kv.Pos(), "invalid field name %s in struct literal", kv.Key)
 						continue
@@ -1105,15 +1106,14 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 					}
 					fld := fields[i]
 					check.recordUse(key, fld)
+					etyp := fld.typ
+					check.assignment(x, etyp, "struct literal")
 					// 0 <= i < len(fields)
 					if visited[i] {
 						check.errorf(kv.Pos(), "duplicate field name %s in struct literal", key.Name)
 						continue
 					}
 					visited[i] = true
-					check.expr(x, kv.Value)
-					etyp := fld.typ
-					check.assignment(x, etyp, "struct literal")
 				}
 			} else {
 				// no element must have a key