Revert "go/types, types2: remove unnecessary tests for x.typ == Typ[Invalid]"

This reverts commit 4c49d52439805c248f4a01d529b90b22e821b7d6.

Reason for revert: it is trickier than expected to enforce an invariant that x.typ == Typ[Invalid] => x.mode == invalid. For example, builtins have invalid type until their call is evaluated.

I think it is better to keep this defensive code for now. My bad for suggesting this strictness. I will send a follow-up CL with a test that exercises the panic discovered inside Google, and a bit more commentary about what 'invalid' means in both contexts.

Fixes #59603

Change-Id: If291f7268e7ef7ae6cd9bb861bb9af349a729cb2
Reviewed-on: https://go-review.googlesource.com/c/go/+/484375
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>

diff --git a/src/cmd/compile/internal/types2/assignments.go b/src/cmd/compile/internal/types2/assignments.go
index 5a51b3de1e2bb29bcd4ef90f4aa0356b1d1ca6a1..02823fed2c6479a5230632c2c6d909a665ed1f5e 100644 (file)
--- a/src/cmd/compile/internal/types2/assignments.go
+++ b/src/cmd/compile/internal/types2/assignments.go
@@ -99,7 +99,7 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
 }
 
 func (check *Checker) initConst(lhs *Const, x *operand) {
-       if x.mode == invalid || lhs.typ == Typ[Invalid] {
+       if x.mode == invalid || x.typ == Typ[Invalid] || lhs.typ == Typ[Invalid] {
                if lhs.typ == nil {
                        lhs.typ = Typ[Invalid]
                }
@@ -133,7 +133,7 @@ func (check *Checker) initConst(lhs *Const, x *operand) {
 // If lhs doesn't have a type yet, it is given the type of x,
 // or Typ[Invalid] in case of an error.
 func (check *Checker) initVar(lhs *Var, x *operand, context string) {
-       if x.mode == invalid || lhs.typ == Typ[Invalid] {
+       if x.mode == invalid || x.typ == Typ[Invalid] || lhs.typ == Typ[Invalid] {
                if lhs.typ == nil {
                        lhs.typ = Typ[Invalid]
                }
@@ -195,6 +195,10 @@ func (check *Checker) lhsVar(lhs syntax.Expr) Type {
                v.used = v_used // restore v.used
        }
 
+       if x.mode == invalid || x.typ == Typ[Invalid] {
+               return Typ[Invalid]
+       }
+
        // spec: "Each left-hand side operand must be addressable, a map index
        // expression, or the blank identifier. Operands may be parenthesized."
        switch x.mode {

diff --git a/src/go/types/assignments.go b/src/go/types/assignments.go
index 5eca569b56840b286c555021a8f2f2f8c1bfae87..68b07a717227773d0781c54983cd0805163e4525 100644 (file)
--- a/src/go/types/assignments.go
+++ b/src/go/types/assignments.go
@@ -97,7 +97,7 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
 }
 
 func (check *Checker) initConst(lhs *Const, x *operand) {
-       if x.mode == invalid || lhs.typ == Typ[Invalid] {
+       if x.mode == invalid || x.typ == Typ[Invalid] || lhs.typ == Typ[Invalid] {
                if lhs.typ == nil {
                        lhs.typ = Typ[Invalid]
                }
@@ -131,7 +131,7 @@ func (check *Checker) initConst(lhs *Const, x *operand) {
 // If lhs doesn't have a type yet, it is given the type of x,
 // or Typ[Invalid] in case of an error.
 func (check *Checker) initVar(lhs *Var, x *operand, context string) {
-       if x.mode == invalid || lhs.typ == Typ[Invalid] {
+       if x.mode == invalid || x.typ == Typ[Invalid] || lhs.typ == Typ[Invalid] {
                if lhs.typ == nil {
                        lhs.typ = Typ[Invalid]
                }
@@ -193,6 +193,10 @@ func (check *Checker) lhsVar(lhs ast.Expr) Type {
                v.used = v_used // restore v.used
        }
 
+       if x.mode == invalid || x.typ == Typ[Invalid] {
+               return Typ[Invalid]
+       }
+
        // spec: "Each left-hand side operand must be addressable, a map index
        // expression, or the blank identifier. Operands may be parenthesized."
        switch x.mode {