Fix up vla, vm and [*] sematics.

	PR c/18740
	PR c/7948
	PR c/25802
	* c-tree.h (struct c_arg_info): Add had_vla_unspec.
	(c_vla_unspec_p): Add.
	(c_vla_type_p): Add.
	* c-decl.c (struct c_scope): Add had_vla_unspec.
	(build_array_declarator): Add support for [*].
	(grokdeclarator): Likewise.
	(grokparms): Likewise.
	(get_parm_info): Likewise.
	* c-objc-common.c (c_vla_unspec_p): Likewise.
	* c-objc-common.h (LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P): Likewise.
	* c-parser.c (c_parser_typeof_specifier): Evaluate arguments to
	typeof when argument is a variably modified type not inside sizeof or alignof.
	(c_parser_direct_declarator_inner): Propagate errors.
	(c_parser_sizeof_expression): Add support for [*].
	* c-typeck.c (c_vla_type_p): Add.
	(composite_type): Add support for vla compositing.
	(comptypes_internal): Add support for vla compatibility.
	(c_expr_sizeof_expr): Evaluate vla arguments.
	* tree.c (variably_modified_type_p): Update comment for [*].

testsuite:
	* gcc.dg/c90-arraydecl-1.c: Update for vla, vm [*] fixups.
	* gcc.dg/vla-4.c: Add.
	* gcc.dg/vla-5.c: Add.
	* gcc.dg/vla-6.c: Add.

From-SVN: r113888

1 files changed, 72 insertions, 15 deletions

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index f4d3330..ea1a8c4 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -331,6 +331,10 @@ struct c_scope GTY((chain_next ("%h.outer")))
      declarations.  */
   BOOL_BITFIELD parm_flag : 1;
 
+  /* True if we saw [*] in this scope.  Used to give an error messages
+     if these appears in a function definition.  */
+  BOOL_BITFIELD had_vla_unspec : 1;
+
   /* True if we already complained about forward parameter decls
      in this scope.  This prevents double warnings on
      foo (int a; int b; ...)  */
@@ -3007,14 +3011,14 @@ quals_from_declspecs (const struct c_declspecs *specs)
   return quals;
 }
 
-/* Construct an array declarator.  EXPR is the expression inside [], or
-   NULL_TREE.  QUALS are the type qualifiers inside the [] (to be applied
-   to the pointer to which a parameter array is converted).  STATIC_P is
-   true if "static" is inside the [], false otherwise.  VLA_UNSPEC_P
-   is true if the array is [*], a VLA of unspecified length which is
-   nevertheless a complete type (not currently implemented by GCC),
-   false otherwise.  The field for the contained declarator is left to be
-   filled in by set_array_declarator_inner.  */
+/* Construct an array declarator.  EXPR is the expression inside [],
+   or NULL_TREE.  QUALS are the type qualifiers inside the [] (to be
+   applied to the pointer to which a parameter array is converted).
+   STATIC_P is true if "static" is inside the [], false otherwise.
+   VLA_UNSPEC_P is true if the array is [*], a VLA of unspecified
+   length which is nevertheless a complete type, false otherwise.  The
+   field for the contained declarator is left to be filled in by
+   set_array_declarator_inner.  */
 
 struct c_declarator *
 build_array_declarator (tree expr, struct c_declspecs *quals, bool static_p,
@@ -3046,7 +3050,16 @@ build_array_declarator (tree expr, struct c_declspecs *quals, bool static_p,
 	pedwarn ("ISO C90 does not support %<[*]%> array declarators");
     }
   if (vla_unspec_p)
-    warning (0, "GCC does not yet properly implement %<[*]%> array declarators");
+    {
+      if (!current_scope->parm_flag)
+	{
+	  /* C99 6.7.5.2p4 */
+	  error ("%<[*]%> not allowed in other than function prototype scope");
+	  declarator->u.array.vla_unspec_p = false;
+	  return NULL;
+	}
+      current_scope->had_vla_unspec = true;
+    }
   return declarator;
 }
 
@@ -3858,20 +3871,21 @@ grokdeclarator (const struct c_declarator *declarator,
   int type_quals = TYPE_UNQUALIFIED;
   const char *name, *orig_name;
   tree typedef_type = 0;
-  int funcdef_flag = 0;
+  bool funcdef_flag = false;
   bool funcdef_syntax = false;
   int size_varies = 0;
   tree decl_attr = declspecs->decl_attr;
   int array_ptr_quals = TYPE_UNQUALIFIED;
   tree array_ptr_attrs = NULL_TREE;
   int array_parm_static = 0;
+  bool array_parm_vla_unspec_p = false;
   tree returned_attrs = NULL_TREE;
   bool bitfield = width != NULL;
   tree element_type;
   struct c_arg_info *arg_info = 0;
 
   if (decl_context == FUNCDEF)
-    funcdef_flag = 1, decl_context = NORMAL;
+    funcdef_flag = true, decl_context = NORMAL;
 
   /* Look inside a declarator for the name being declared
      and get it as a string, for an error message.  */
@@ -4137,7 +4151,8 @@ grokdeclarator (const struct c_declarator *declarator,
 	    array_ptr_quals = declarator->u.array.quals;
 	    array_ptr_attrs = declarator->u.array.attrs;
 	    array_parm_static = declarator->u.array.static_p;
-	    
+	    array_parm_vla_unspec_p = declarator->u.array.vla_unspec_p;
+
 	    declarator = declarator->declarator;
 
 	    /* Check for some types that there cannot be arrays of.  */
@@ -4262,6 +4277,20 @@ grokdeclarator (const struct c_declarator *declarator,
 		   identical to GCC's zero-length array extension.  */
 		itype = build_range_type (sizetype, size_zero_node, NULL_TREE);
 	      }
+	    else if (decl_context == PARM)
+	      {
+		if (array_parm_vla_unspec_p)
+		  {
+		    if (! orig_name)
+		      {
+			/* C99 6.7.5.2p4 */
+			error ("%<[*]%> not allowed in other than a declaration");
+		      }
+
+		    itype = build_range_type (sizetype, size_zero_node, NULL_TREE);
+		    size_varies = 1;
+		  }
+	      }
 
 	     /* Complain about arrays of incomplete types.  */
 	    if (!COMPLETE_TYPE_P (type))
@@ -4275,7 +4304,7 @@ grokdeclarator (const struct c_declarator *declarator,
 	    if (type != error_mark_node)
 	      {
 		if (size_varies)
-		C_TYPE_VARIABLE_SIZE (type) = 1;
+		  C_TYPE_VARIABLE_SIZE (type) = 1;
 
 		/* The GCC extension for zero-length arrays differs from
 		   ISO flexible array members in that sizeof yields
@@ -4285,6 +4314,12 @@ grokdeclarator (const struct c_declarator *declarator,
 		    TYPE_SIZE (type) = bitsize_zero_node;
 		    TYPE_SIZE_UNIT (type) = size_zero_node;
 		  }
+		if (array_parm_vla_unspec_p)
+		  {
+		    /* The type is complete.  C99 6.7.5.2p4  */
+		    TYPE_SIZE (type) = bitsize_zero_node;
+		    TYPE_SIZE_UNIT (type) = size_zero_node;
+		  }
 	      }
 
 	    if (decl_context != PARM
@@ -4472,6 +4507,13 @@ grokdeclarator (const struct c_declarator *declarator,
       return type;
     }
 
+  if (pedantic && decl_context == FIELD
+      && variably_modified_type_p (type, NULL_TREE))
+    {
+      /* C99 6.7.2.1p8 */
+      pedwarn ("a member of a structure or union cannot have a variably modified type");
+    }
+
   /* Aside from typedefs and type names (handle above),
      `void' at top level (not within pointer)
      is allowed only in public variables.
@@ -4737,6 +4779,13 @@ grokdeclarator (const struct c_declarator *declarator,
 	  }
       }
 
+    if (storage_class == csc_extern
+	&& variably_modified_type_p (type, NULL_TREE))
+      {
+	/* C99 6.7.5.2p2 */
+	error ("object with variably modified type must have no linkage");
+      }
+
     /* Record `register' declaration for warnings on &
        and in case doing stupid register allocation.  */
 
@@ -4778,7 +4827,7 @@ grokdeclarator (const struct c_declarator *declarator,
 }
 
 /* Decode the parameter-list info for a function type or function definition.
-   The argument is the value returned by `get_parm_info' (or made in parse.y
+   The argument is the value returned by `get_parm_info' (or made in c-parse.c
    if there is an identifier list instead of a parameter decl list).
    These two functions are separate because when a function returns
    or receives functions then each is called multiple times but the order
@@ -4796,6 +4845,13 @@ grokparms (struct c_arg_info *arg_info, bool funcdef_flag)
 {
   tree arg_types = arg_info->types;
 
+  if (funcdef_flag && arg_info->had_vla_unspec)
+    {
+      /* A function definition isn't function prototype scope C99 6.2.1p4.  */
+      /* C99 6.7.5.2p4 */
+      error ("%<[*]%> not allowed in other than function prototype scope");
+    }
+
   if (arg_types == 0 && !funcdef_flag && !in_system_header)
     warning (OPT_Wstrict_prototypes,
 	     "function declaration isn%'t a prototype");
@@ -4892,6 +4948,7 @@ get_parm_info (bool ellipsis)
   arg_info->tags = 0;
   arg_info->types = 0;
   arg_info->others = 0;
+  arg_info->had_vla_unspec = current_scope->had_vla_unspec;
 
   /* The bindings in this scope must not get put into a block.
      We will take care of deleting the binding nodes.  */
@@ -5541,7 +5598,7 @@ finish_struct (tree t, tree fieldlist, tree attributes)
   /* 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 (cur_stmt_list && variably_modified_type_p (t, NULL))
+  if (cur_stmt_list && variably_modified_type_p (t, NULL_TREE))
     add_stmt (build_stmt (DECL_EXPR, build_decl (TYPE_DECL, NULL, t)));
 
   return t;