re PR c/39605 ("error: variable-size type declared outside of any function" is issued twice)

	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.

From-SVN: r145405

6 files changed, 47 insertions, 5 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f4b1e56..1eebf64 100644
--- 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
--- 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
--- 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
--- 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
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
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" } */