gcc does not reject jumps over the declaration of a variable length array: void f(int l) { goto label; int a[l]; label:; } void g (int l) { switch (l) { case 1:; int a[l]; default:; } } gcc 3.3 rejects at least the first case with the pretty misleading error message test.c:4: error: label `label' used before containing binding contour but mainline accepts both.
In fact c++ front-end rejects only first one in 3.4 also.
Mainline (20031107) has the same error message you got in 3.3. I certainly didn't find the message helpful though. Does mainline still accept this for you?
Mainline gives an error message for f1 now, but still not for f2.
Erm, I meant f and g, of course. And the misleading diagnostic worries me much less than the accepts-invalid, which most likely will do something the user didn't intend...
It is even worse (at least as I can see) on the tree-ssa because it will produce the following code: int a[l.1 * 4]; void * saved_stack.3; long unsigned int T.2; long unsigned int l.1; int l.0; <bb 0>: switch (l) { case 1: goto <L0>; default : goto <L1>; } <L0>:; l.0 = 1; l.1 = (long unsigned int)l.0; T.2 = l.1 * 4; __builtin_stack_alloc (&a, T.2); <L1>:; __builtin_stack_restore (saved_stack.3); return; so it will try do restore even though it did not save anything.
Testing a fix. Note that the first case is a regression in 4.0 relative to previous releases, so I'll propose the fix for 4.0.1.
Subject: Bug 12913 CVSROOT: /cvs/gcc Module name: gcc Changes by: jsm28@gcc.gnu.org 2005-04-20 16:41:48 Modified files: gcc : ChangeLog c-decl.c c-tree.h c-typeck.c gcc/objc : ChangeLog objc-act.c gcc/testsuite : ChangeLog Added files: gcc/testsuite/gcc.dg: c99-vla-jump-1.c c99-vla-jump-2.c c99-vla-jump-3.c c99-vla-jump-4.c c99-vla-jump-5.c Log message: PR c/12913 * c-tree.h (struct c_label_list): Update comment. (struct c_label_context): Rename to struct c_label_context_se. (label_context_stack): Rename to label_context_stack_se. (C_DECL_UNJUMPABLE_VM, C_DECL_UNDEFINABLE_VM, struct c_label_context_vm, label_context_stack_vm, c_begin_vm_scope, c_end_vm_scope): New. (C_DECL_DECLARED_BUILTIN, C_DECL_USED): Use FUNCTION_DECL_CHECK. * c-decl.c (pop_scope): Call c_end_vm_scope. (pushdecl): Call c_begin_vm_scope for variably modified declarations. (define_label): Check for jumping into scope of identifier with variably modified type. Push label on stack for those defined at current context of identifiers with variably modified type. (start_function): Create stack level for context of identifiers with variably modified type. (finish_function): Pop stack level for context of identifiers with variably modified type. * c-typeck.c (label_context_stack): Rename to label_context_stack_se. (label_context_stack_vm, c_begin_vm_scope, c_end_vm_scope): New. (c_finish_goto_label): Check for jumping into scope of identifier with variably modified type. Push label on stack for those jumped to from current context of identifiers with variably modified type. (struct c_switch): Add blocked_vm. (c_start_case): Initialize blocked_vm. (do_case): Check blocked_vm. (c_finish_case): Add comment. (c_begin_stmt_expr, c_finish_stmt_expr): Update for renamed variable label_context_stack. objc: * objc-act.c (objc_start_function): Create stack level for context of identifiers with variably modified type. testsuite: * gcc.dg/c99-vla-jump-1.c, gcc.dg/c99-vla-jump-2.c, gcc.dg/c99-vla-jump-3.c, gcc.dg/c99-vla-jump-4.c, gcc.dg/c99-vla-jump-5.c: New tests. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.8375&r2=2.8376 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/c-decl.c.diff?cvsroot=gcc&r1=1.646&r2=1.647 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/c-tree.h.diff?cvsroot=gcc&r1=1.200&r2=1.201 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/c-typeck.c.diff?cvsroot=gcc&r1=1.433&r2=1.434 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/objc/ChangeLog.diff?cvsroot=gcc&r1=1.32&r2=1.33 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/objc/objc-act.c.diff?cvsroot=gcc&r1=1.269&r2=1.270 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.5375&r2=1.5376 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-1.c.diff?cvsroot=gcc&r1=NONE&r2=1.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-2.c.diff?cvsroot=gcc&r1=NONE&r2=1.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-3.c.diff?cvsroot=gcc&r1=NONE&r2=1.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-4.c.diff?cvsroot=gcc&r1=NONE&r2=1.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-5.c.diff?cvsroot=gcc&r1=NONE&r2=1.1
Subject: Bug 12913 CVSROOT: /cvs/gcc Module name: gcc Branch: gcc-4_0-branch Changes by: jsm28@gcc.gnu.org 2005-04-22 12:58:43 Modified files: gcc : ChangeLog c-decl.c c-tree.h c-typeck.c gcc/objc : ChangeLog objc-act.c gcc/testsuite : ChangeLog Added files: gcc/testsuite/gcc.dg: c99-vla-jump-1.c c99-vla-jump-2.c c99-vla-jump-3.c c99-vla-jump-4.c c99-vla-jump-5.c Log message: PR c/12913 * c-tree.h (struct c_label_list): Update comment. (struct c_label_context): Rename to struct c_label_context_se. (label_context_stack): Rename to label_context_stack_se. (C_DECL_UNJUMPABLE_VM, C_DECL_UNDEFINABLE_VM, struct c_label_context_vm, label_context_stack_vm, c_begin_vm_scope, c_end_vm_scope): New. (C_DECL_DECLARED_BUILTIN, C_DECL_USED): Use FUNCTION_DECL_CHECK. * c-decl.c (pop_scope): Call c_end_vm_scope. (pushdecl): Call c_begin_vm_scope for variably modified declarations. (define_label): Check for jumping into scope of identifier with variably modified type. Push label on stack for those defined at current context of identifiers with variably modified type. (start_function): Create stack level for context of identifiers with variably modified type. (finish_function): Pop stack level for context of identifiers with variably modified type. * c-typeck.c (label_context_stack): Rename to label_context_stack_se. (label_context_stack_vm, c_begin_vm_scope, c_end_vm_scope): New. (c_finish_goto_label): Check for jumping into scope of identifier with variably modified type. Push label on stack for those jumped to from current context of identifiers with variably modified type. (struct c_switch): Add blocked_vm. (c_start_case): Initialize blocked_vm. (do_case): Check blocked_vm. (c_finish_case): Add comment. (c_begin_stmt_expr, c_finish_stmt_expr): Update for renamed variable label_context_stack. objc: * objc-act.c (objc_start_function): Create stack level for context of identifiers with variably modified type. testsuite: * gcc.dg/c99-vla-jump-1.c, gcc.dg/c99-vla-jump-2.c, gcc.dg/c99-vla-jump-3.c, gcc.dg/c99-vla-jump-4.c, gcc.dg/c99-vla-jump-5.c: New tests. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=2.7592.2.175&r2=2.7592.2.176 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/c-decl.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.630.6.6&r2=1.630.6.7 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/c-tree.h.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.193.4.2&r2=1.193.4.3 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/c-typeck.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.419.2.1&r2=1.419.2.2 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/objc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.29.8.2&r2=1.29.8.3 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/objc/objc-act.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.266.6.1&r2=1.266.6.2 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.5084.2.131&r2=1.5084.2.132 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-1.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=NONE&r2=1.1.2.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-2.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=NONE&r2=1.1.2.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-3.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=NONE&r2=1.1.2.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-4.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=NONE&r2=1.1.2.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/c99-vla-jump-5.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=NONE&r2=1.1.2.1
Fixed.