compiler: Flatten erroneous subtrees into errors.

    
    Between the lowering and flattening passes of the compiler, there are
    several passes that modify the lowered Go parse tree and as errors are
    discovered, several nodes transform into error nodes.  However, for a
    higher level node such as a construction expression, the erroneous
    nodes in the subtrees might not propagate their error.  The flatten
    phase for a node now looks for errors in the subtree and flattens the
    node into an error node if any are found.
    
    Fixes golang/go#11559, golang/go#11536, golang/go#11558.
    
    Reviewed-on: https://go-review.googlesource.com/13097

From-SVN: r226845

gcc/go/gofrontend/MERGE

-5fc38e74d132cd6f4e7b56e6bcf9fe57031ab203
+fc9da313b4f5c13b4ac3bdddd98e699fd1c89613
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/expressions.h

@@ -1958,6 +1958,11 @@ class Call_expression : public Expression
   bool
   issue_error();
 
+  // Whether or not this call contains errors, either in the call or the
+  // arguments to the call.
+  bool
+  is_erroneous_call();
+
   // Whether this call returns multiple results that are used as an
   // multi-valued argument.
   bool

gcc/go/gofrontend/statements.cc

@@ -253,6 +253,14 @@ Statement*
 Variable_declaration_statement::do_flatten(Gogo* gogo, Named_object* function,
                                            Block*, Statement_inserter* inserter)
 {
+  Variable* var = this->var_->var_value();
+  if (var->type()->is_error_type()
+      || (var->init() != NULL
+          && var->init()->is_error_expression()))
+    {
+      go_assert(saw_errors());
+      return Statement::make_error_statement(this->location());
+    }
   this->var_->var_value()->flatten_init_expression(gogo, function, inserter);
   return this;
 }
@@ -437,6 +445,14 @@ Statement*
 Temporary_statement::do_flatten(Gogo*, Named_object*, Block*,
 				Statement_inserter* inserter)
 {
+  if (this->type()->is_error_type()
+      || (this->init_ != NULL
+          && this->init_->is_error_expression()))
+    {
+      go_assert(saw_errors());
+      return Statement::make_error_statement(this->location());
+    }
+
   if (this->type_ != NULL
       && this->init_ != NULL
       && !Type::are_identical(this->type_, this->init_->type(), false, NULL)
@@ -610,6 +626,15 @@ Statement*
 Assignment_statement::do_flatten(Gogo*, Named_object*, Block*,
 				 Statement_inserter* inserter)
 {
+  if (this->lhs_->is_error_expression()
+      || this->lhs_->type()->is_error_type()
+      || this->rhs_->is_error_expression()
+      || this->rhs_->type()->is_error_type())
+    {
+      go_assert(saw_errors());
+      return Statement::make_error_statement(this->location());
+    }
+
   if (!this->lhs_->is_sink_expression()
       && !Type::are_identical(this->lhs_->type(), this->rhs_->type(),
 			      false, NULL)
@@ -4397,6 +4422,13 @@ Statement*
 Send_statement::do_flatten(Gogo*, Named_object*, Block*,
 			   Statement_inserter* inserter)
 {
+  if (this->channel_->is_error_expression()
+      || this->channel_->type()->is_error_type())
+    {
+      go_assert(saw_errors());
+      return Statement::make_error_statement(this->location());
+    }
+
   Type* element_type = this->channel_->type()->channel_type()->element_type();
   if (!Type::are_identical(element_type, this->val_->type(), false, NULL)
       && this->val_->type()->interface_type() != NULL