PR c/39605

	* c-decl.c (grokdeclarator): Pedwarn for file-scope array
	declarator whose size is not an integer constant expression but
	folds to an integer constant, then treat it as a constant
	subsequently.

testsuite:
	* gcc.dg/vla-17.c, gcc.dg/vla-18.c: New tests.
	* gcc.dg/pr25682.c: Update expected diagnostics.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@145405 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f4b1e56..1eebf64 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2009-04-01  Joseph Myers  <joseph@codesourcery.com>
+
+       PR c/39605
+       * c-decl.c (grokdeclarator): Pedwarn for file-scope array
+       declarator whose size is not an integer constant expression but
+       folds to an integer constant, then treat it as a constant
+       subsequently.
+
 2009-04-01  Richard Guenther  <rguenther@suse.de>
 
        * fold-const.c (fold_plusminus_mult_expr): Do not fold

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index 3c1c277..9202feb 100644 (file)
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -4408,7 +4408,17 @@ grokdeclarator (const struct c_declarator *declarator,
                       not an integer constant expression.  */
                    if (!size_int_const)
                      {
-                       this_size_varies = size_varies = 1;
+                       /* If this is a file scope declaration of an
+                          ordinary identifier, this is invalid code;
+                          diagnosing it here and not subsequently
+                          treating the type as variable-length avoids
+                          more confusing diagnostics later.  */
+                       if ((decl_context == NORMAL || decl_context == FIELD)
+                           && current_scope == file_scope)
+                         pedwarn (input_location, 0,
+                                  "variably modified %qs at file scope", name);
+                       else
+                         this_size_varies = size_varies = 1;
                        warn_variable_length_array (orig_name, size);
                      }
                  }

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5462bea..16d9340 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2009-04-01  Joseph Myers  <joseph@codesourcery.com>
+
+       PR c/39605
+       * gcc.dg/vla-17.c, gcc.dg/vla-18.c: New tests.
+       * gcc.dg/pr25682.c: Update expected diagnostics.
+
 2009-04-01  Richard Guenther  <rguenther@suse.de>
 
        * gcc.dg/fold-plusmult-2.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/pr25682.c b/gcc/testsuite/gcc.dg/pr25682.c
index c99b891..8c51d82 100644 (file)
--- a/gcc/testsuite/gcc.dg/pr25682.c
+++ b/gcc/testsuite/gcc.dg/pr25682.c
@@ -10,10 +10,10 @@ struct S
   int b;
 };
 
-char c[(char *) &((struct S *) 0)->b - (char *) 0]; /* { dg-error "variable-size" } */
-char d[(__SIZE_TYPE__) &((struct S *) 8)->b]; /* { dg-error "variable-size" } */
-char e[sizeof (c) == __builtin_offsetof (struct S, b) ? 1 : -1]; /* { dg-error "variably modified" } */
-char f[sizeof (d) == __builtin_offsetof (struct S, b) + 8 ? 1 : -1]; /* { dg-error "variably modified" } */
+char c[(char *) &((struct S *) 0)->b - (char *) 0]; /* { dg-warning "variably modified" } */
+char d[(__SIZE_TYPE__) &((struct S *) 8)->b]; /* { dg-warning "variably modified" } */
+char e[sizeof (c) == __builtin_offsetof (struct S, b) ? 1 : -1];
+char f[sizeof (d) == __builtin_offsetof (struct S, b) + 8 ? 1 : -1];
 
 extern void bar (char *, char *);
 

diff --git a/gcc/testsuite/gcc.dg/vla-17.c b/gcc/testsuite/gcc.dg/vla-17.c
new file mode 100644 (file)
index 0000000..07d3930
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-17.c
@@ -0,0 +1,9 @@
+/* Test diagnostics for VLA whose size folds to an integer constant at
+   file scope.  PR 39605.  */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+#define FIRST ((void*)0x80)
+#define LAST  ((void*)0x86)
+
+static int b[LAST-FIRST]; /* { dg-warning "variably modified 'b' at file scope" } */

diff --git a/gcc/testsuite/gcc.dg/vla-18.c b/gcc/testsuite/gcc.dg/vla-18.c
new file mode 100644 (file)
index 0000000..c60069c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vla-18.c
@@ -0,0 +1,9 @@
+/* Test diagnostics for VLA whose size folds to an integer constant at
+   file scope; the diagnostic should be a pedwarn.  PR 39605.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c99 -pedantic-errors" } */
+
+#define FIRST ((char*)0x80)
+#define LAST  ((char*)0x86)
+
+static int b[LAST-FIRST]; /* { dg-error "variably modified 'b' at file scope" } */