Fix ICEs related to VM types in C 1/2 [PR70418, PR107557, PR108423]

Size expressions were sometimes lost and not gimplified correctly, leading to
ICEs and incorrect evaluation order.  Fix this by 1) not recursing into
pointers when gimplifying parameters in the middle-end (the code is merged with
gimplify_type_sizes), which is incorrect because it might access variables
declared later for incomplete structs, and 2) tracking size expressions for
struct/union members correctly, 3) emitting code to evaluate size expressions
for missing cases (nested functions, empty declarations, and structs/unions).

	PR c/70418
	PR c/106465
	PR c/107557
	PR c/108423

	gcc/c/
	* c-decl.cc (start_decl): Make sure size expression are
	evaluated only in correct context.
	(grokdeclarator): Size expression in fields may need a bind
	expression, make sure DECL_EXPR is always created.
	(grokfield, declspecs_add_type): Pass along size expressions.
	(finish_struct): Remove unneeded DECL_EXPR.
	(start_function): Evaluate size expressions for nested functions.
	* c-parser.cc (c_parser_struct_declarations,
	c_parser_struct_or_union_specifier): Pass along size expressions.
	(c_parser_declaration_or_fndef): Evaluate size expression.
	(c_parser_objc_at_property_declaration,
	c_parser_objc_class_instance_variables): Adapt.
	* c-tree.h (grokfield): Adapt declaration.

	gcc/testsuite/
	* gcc.dg/nested-vla-1.c: New test.
	* gcc.dg/nested-vla-2.c: New test.
	* gcc.dg/nested-vla-3.c: New test.
	* gcc.dg/pr70418.c: New test.
	* gcc.dg/pr106465.c: New test.
	* gcc.dg/pr107557-1.c: New test.
	* gcc.dg/pr107557-2.c: New test.
	* gcc.dg/pr108423-1.c: New test.
	* gcc.dg/pr108423-2.c: New test.
	* gcc.dg/pr108423-3.c: New test.
	* gcc.dg/pr108423-4.c: New test.
	* gcc.dg/pr108423-5.c: New test.
	* gcc.dg/pr108423-6.c: New test.
	* gcc.dg/typename-vla-2.c: New test.
	* gcc.dg/typename-vla-3.c: New test.
	* gcc.dg/typename-vla-4.c: New test.
	* gcc.misc-tests/gcov-pr85350.c: Adapt.

1 files changed, 22 insertions, 17 deletions

diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index 94ce760..494d3cf 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -5364,7 +5364,8 @@ start_decl (struct c_declarator *declarator, struct c_declspecs *declspecs,
     if (lastdecl != error_mark_node)
       *lastloc = DECL_SOURCE_LOCATION (lastdecl);
 
-  if (expr)
+  /* Make sure the size expression is evaluated at this point.  */
+  if (expr && !current_scope->parm_flag)
     add_stmt (fold_convert (void_type_node, expr));
 
   if (TREE_CODE (decl) != FUNCTION_DECL && MAIN_NAME_P (DECL_NAME (decl))
@@ -7498,7 +7499,8 @@ grokdeclarator (const struct c_declarator *declarator,
 		&& c_type_variably_modified_p (type))
 	      {
 		tree bind = NULL_TREE;
-		if (decl_context == TYPENAME || decl_context == PARM)
+		if (decl_context == TYPENAME || decl_context == PARM
+		    || decl_context == FIELD)
 		  {
 		    bind = build3 (BIND_EXPR, void_type_node, NULL_TREE,
 				   NULL_TREE, NULL_TREE);
@@ -7507,10 +7509,11 @@ grokdeclarator (const struct c_declarator *declarator,
 		    push_scope ();
 		  }
 		tree decl = build_decl (loc, TYPE_DECL, NULL_TREE, type);
-		DECL_ARTIFICIAL (decl) = 1;
 		pushdecl (decl);
-		finish_decl (decl, loc, NULL_TREE, NULL_TREE, NULL_TREE);
+		DECL_ARTIFICIAL (decl) = 1;
+		add_stmt (build_stmt (DECL_SOURCE_LOCATION (decl), DECL_EXPR, decl));
 		TYPE_NAME (type) = decl;
+
 		if (bind)
 		  {
 		    pop_scope ();
@@ -8709,7 +8712,7 @@ start_struct (location_t loc, enum tree_code code, tree name,
 tree
 grokfield (location_t loc,
 	   struct c_declarator *declarator, struct c_declspecs *declspecs,
-	   tree width, tree *decl_attrs)
+	   tree width, tree *decl_attrs, tree *expr)
 {
   tree value;
 
@@ -8766,7 +8769,7 @@ grokfield (location_t loc,
     }
 
   value = grokdeclarator (declarator, declspecs, FIELD, false,
-			  width ? &width : NULL, decl_attrs, NULL, NULL,
+			  width ? &width : NULL, decl_attrs, expr, NULL,
 			  DEPRECATED_NORMAL);
 
   finish_decl (value, loc, NULL_TREE, NULL_TREE, NULL_TREE);
@@ -9424,13 +9427,6 @@ finish_struct (location_t loc, tree t, tree fieldlist, tree attributes,
 
   finish_incomplete_vars (incomplete_vars, toplevel);
 
-  /* If we're inside a function proper, i.e. not file-scope and not still
-     parsing parameters, then arrange for the size of a variable sized type
-     to be bound now.  */
-  if (building_stmt_list_p () && c_type_variably_modified_p(t))
-    add_stmt (build_stmt (loc,
-			  DECL_EXPR, build_decl (loc, TYPE_DECL, NULL, t)));
-
   if (warn_cxx_compat)
     warn_cxx_compat_finish_struct (fieldlist, TREE_CODE (t), loc);
 
@@ -10056,6 +10052,7 @@ start_function (struct c_declspecs *declspecs, struct c_declarator *declarator,
   tree restype, resdecl;
   location_t loc;
   location_t result_loc;
+  tree expr = NULL;
 
   current_function_returns_value = 0;  /* Assume, until we see it does.  */
   current_function_returns_null = 0;
@@ -10067,7 +10064,7 @@ start_function (struct c_declspecs *declspecs, struct c_declarator *declarator,
   in_statement = 0;
 
   decl1 = grokdeclarator (declarator, declspecs, FUNCDEF, true, NULL,
-			  &attributes, NULL, NULL, DEPRECATED_NORMAL);
+			  &attributes, &expr, NULL, DEPRECATED_NORMAL);
   invoke_plugin_callbacks (PLUGIN_START_PARSE_FUNCTION, decl1);
 
   /* If the declarator is not suitable for a function definition,
@@ -10076,6 +10073,11 @@ start_function (struct c_declspecs *declspecs, struct c_declarator *declarator,
       || TREE_CODE (decl1) != FUNCTION_DECL)
     return false;
 
+  /* Nested functions may have variably modified (return) type.
+     Make sure the size expression is evaluated at this point.  */
+  if (expr && !current_scope->parm_flag)
+    add_stmt (fold_convert (void_type_node, expr));
+
   loc = DECL_SOURCE_LOCATION (decl1);
 
   /* A nested function is not global.  */
@@ -12284,10 +12286,13 @@ declspecs_add_type (location_t loc, struct c_declspecs *specs,
     }
   else
     {
-      if (TREE_CODE (type) != ERROR_MARK && spec.kind == ctsk_typeof)
+      if (TREE_CODE (type) != ERROR_MARK)
 	{
-	  specs->typedef_p = true;
-	  specs->locations[cdw_typedef] = loc;
+	  if (spec.kind == ctsk_typeof)
+	    {
+	      specs->typedef_p = true;
+	      specs->locations[cdw_typedef] = loc;
+	    }
 	  if (spec.expr)
 	    {
 	      if (specs->expr)