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re PR c/39581 (VLA types at file scope wrongly rejected)

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PR c/39581
	* c-decl.c (global_bindings_p): Return negative value.
	(c_variable_size): New.  Based on variable_size from
	stor-layout.c.
	(grokdeclarator): Call c_variable_size not variable_size.

testsuite:
	* gcc.dg/c99-const-expr-14.c, gcc.dg/gnu99-const-expr-4.c,
	gcc.dg/vla-21.c: New tests.

From-SVN: r146806
This commit is contained in:
Joseph Myers 2009-04-26 18:00:04 +01:00 committed by Joseph Myers
parent f6a51d3184
commit e11187cc94
6 changed files with 117 additions and 2 deletions

8
gcc/ChangeLog

@ -1,3 +1,11 @@
2009-04-26 Joseph Myers <joseph@codesourcery.com>
PR c/39581
* c-decl.c (global_bindings_p): Return negative value.
(c_variable_size): New. Based on variable_size from
stor-layout.c.
(grokdeclarator): Call c_variable_size not variable_size.
2009-04-26 Uros Bizjak <ubizjak@gmail.com>
* config/i386/i386.c (print_operand) ['z']: Fix typo.

34
gcc/c-decl.c

@ -663,7 +663,9 @@ objc_mark_locals_volatile (void *enclosing_blk)
int
global_bindings_p (void)
{
return current_scope == file_scope && !c_override_global_bindings_to_false;
return (current_scope == file_scope && !c_override_global_bindings_to_false
? -1
: 0);
}
void
@ -4015,6 +4017,34 @@ warn_variable_length_array (const char *name, tree size)
}
}
/* Given a size SIZE that may not be a constant, return a SAVE_EXPR to
serve as the actual size-expression for a type or decl. This is
like variable_size in stor-layout.c, but we make global_bindings_p
return negative to avoid calls to that function from outside the
front end resulting in errors at file scope, then call this version
instead from front-end code. */
static tree
c_variable_size (tree size)
{
tree save;
if (TREE_CONSTANT (size))
return size;
size = save_expr (size);
save = skip_simple_arithmetic (size);
if (cfun && cfun->dont_save_pending_sizes_p)
return size;
if (!global_bindings_p ())
put_pending_size (save);
return size;
}
/* Given declspecs and a declarator,
determine the name and type of the object declared
and construct a ..._DECL node for it.
@ -4479,7 +4509,7 @@ grokdeclarator (const struct c_declarator *declarator,
MINUS_EXPR, which allows the -1 to get folded
with the +1 that happens when building TYPE_SIZE. */
if (size_varies)
size = variable_size (size);
size = c_variable_size (size);
if (this_size_varies && TREE_CODE (size) == INTEGER_CST)
size = build2 (COMPOUND_EXPR, TREE_TYPE (size),
integer_zero_node, size);

6
gcc/testsuite/ChangeLog

@ -1,3 +1,9 @@
2009-04-26 Joseph Myers <joseph@codesourcery.com>
PR c/39581
* gcc.dg/c99-const-expr-14.c, gcc.dg/gnu99-const-expr-4.c,
gcc.dg/vla-21.c: New tests.
2009-04-26 Joseph Myers <joseph@codesourcery.com>
PR c/39556

35
gcc/testsuite/gcc.dg/c99-const-expr-14.c Normal file

@ -0,0 +1,35 @@
/* Test for constant expressions: cases involving VLAs, at file scope. */
/* Origin: Joseph Myers <joseph@codesourcery.com> */
/* { dg-do compile } */
/* { dg-options "-std=iso9899:1999 -pedantic-errors" } */
/* It appears address constants may contain casts to variably modified
types. Whether they should be permitted was discussed in
<http://groups.google.com/group/comp.std.c/msg/923eee5ab690fd98>
<LV7g2Vy3ARF$Ew9Q@romana.davros.org>; since static pointers to VLAs
are definitely permitted within functions and may be initialized
and such initialization involves implicit conversion to a variably
modified type, allowing explicit casts seems appropriate. Thus,
GCC allows them as long as the "evaluated" size expressions do not
contain the various operators not permitted to be evaluated in a
constant expression, and as long as the result is genuinely
constant (meaning that pointer arithmetic using the size of the VLA
is generally not permitted). */
static int sa[100];
volatile int nv;
int m;
int n;
int f (int, int);
static int (*a2)[] = (int (*)[n])sa;
static int (*a8)[] = (int (*)[(m=n)])sa; /* { dg-error "constant" } */
static int (*a9)[] = (int (*)[(m+=n)])sa; /* { dg-error "constant" } */
static int (*a10)[] = (int (*)[f(m,n)])sa; /* { dg-error "constant" } */
static int (*a11)[] = (int (*)[(m,n)])sa; /* { dg-error "constant" } */
static int (*a12)[] = (int (*)[sizeof(int[n])])sa;
static int (*a13)[] = (int (*)[sizeof(int[m++])])sa; /* { dg-error "constant" } */
static int (*a15)[] = (int (*)[sizeof(*(int (*)[n])sa)])sa;
static int (*a16)[] = (int (*)[sizeof(*(int (*)[m++])sa)])sa; /* { dg-error "constant" } */
static int (*a17)[] = (int (*)[nv])sa;

29
gcc/testsuite/gcc.dg/gnu99-const-expr-4.c Normal file

@ -0,0 +1,29 @@
/* Test for constant expressions: cases involving VLAs and typeof, at
file scope. */
/* Origin: Joseph Myers <joseph@codesourcery.com> */
/* { dg-do compile } */
/* { dg-options "-std=gnu99 -pedantic-errors" } */
/* It appears address constants may contain casts to variably modified
types. Whether they should be permitted was discussed in
<http://groups.google.com/group/comp.std.c/msg/923eee5ab690fd98>
<LV7g2Vy3ARF$Ew9Q@romana.davros.org>; since static pointers to VLAs
are definitely permitted within functions and may be initialized
and such initialization involves implicit conversion to a variably
modified type, allowing explicit casts seems appropriate. Thus,
GCC allows them as long as the "evaluated" size expressions do not
contain the various operators not permitted to be evaluated in a
constant expression, and as long as the result is genuinely
constant (meaning that pointer arithmetic using the size of the VLA
is generally not permitted). */
static int sa[100];
int m;
int n;
static int (*a1)[] = &sa;
static int (*a2)[] = (__typeof__(int (*)[n]))sa;
static int (*a4)[] = (__typeof__((int (*)[n])sa))sa;
static int (*a5)[] = (__typeof__((int (*)[m++])sa))sa; /* { dg-error "constant" } */
static int (*a6)[] = (__typeof__((int (*)[100])(int (*)[m++])sa))sa;
static int (*a7)[] = (__typeof__((int (*)[n])sa + m++))sa; /* { dg-error "constant" } */

7
gcc/testsuite/gcc.dg/vla-21.c Normal file

@ -0,0 +1,7 @@
/* Type names for VLAs should be allowed outside functions if the size
is not evaluated. PR 39581. */
/* { dg-do compile } */
/* { dg-options "-std=c99 -pedantic-errors" } */
int a;
int b = sizeof (int (*)[a]);