re PR c/58346 (ICE with SIGFPE at -O1 and above on x86_64-linux-gnu (affecting trunk, 4.8, 4.7, and 4.6))

	PR c/58346
c-family/
	* c-common.c (pointer_to_zero_sized_aggr_p): New function.
	* c-common.h: Declare it.
cp/
	* typeck.c (pointer_diff): Give an error on arithmetic on pointer to
	an empty aggregate.
c/
	* c-typeck.c (pointer_diff): Give an error on arithmetic on pointer to
	an empty aggregate.
testsuite/
	* c-c++-common/pr58346-1.c: New test.
	* c-c++-common/pr58346-2.c: New test.
	* c-c++-common/pr58346-3.c: New test.

From-SVN: r207004

11 files changed, 96 insertions, 0 deletions

diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 3198558..cba9f4e 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,9 @@
+2014-01-23  Marek Polacek  <polacek@redhat.com>
+
+	PR c/58346
+	* c-common.c (pointer_to_zero_sized_aggr_p): New function.
+	* c-common.h: Declare it.
+
 2014-01-20  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* c-ada-spec.h (dump_ada_specs): Revert prototype change.
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 35958ea..0912801 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -11823,4 +11823,15 @@ cxx_fundamental_alignment_p  (unsigned align)
 			 TYPE_ALIGN (long_double_type_node)));
 }
 
+/* Return true if T is a pointer to a zero-sized aggregate.  */
+
+bool
+pointer_to_zero_sized_aggr_p (tree t)
+{
+  if (!POINTER_TYPE_P (t))
+    return false;
+  t = TREE_TYPE (t);
+  return (TYPE_SIZE (t) && integer_zerop (TYPE_SIZE (t)));
+}
+
 #include "gt-c-family-c-common.h"
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 7e3ece6..dab0b8c 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -789,6 +789,7 @@ extern bool keyword_is_storage_class_specifier (enum rid);
 extern bool keyword_is_type_qualifier (enum rid);
 extern bool keyword_is_decl_specifier (enum rid);
 extern bool cxx_fundamental_alignment_p (unsigned);
+extern bool pointer_to_zero_sized_aggr_p (tree);
 
 #define c_sizeof(LOC, T)  c_sizeof_or_alignof_type (LOC, T, true, false, 1)
 #define c_alignof(LOC, T) c_sizeof_or_alignof_type (LOC, T, false, false, 1)
diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index 237ac1a..4088912 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,5 +1,11 @@
 2014-01-23  Marek Polacek  <polacek@redhat.com>
 
+	PR c/58346
+	* c-typeck.c (pointer_diff): Give an error on arithmetic on pointer to
+	an empty aggregate.
+
+2014-01-23  Marek Polacek  <polacek@redhat.com>
+
 	PR c/59871
 	* c-typeck.c (build_compound_expr): Warn even for right-hand operand
 	of a comma expression.
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 781d4df..77f3bdd 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -3536,6 +3536,9 @@ pointer_diff (location_t loc, tree op0, tree op1)
   /* This generates an error if op0 is pointer to incomplete type.  */
   op1 = c_size_in_bytes (target_type);
 
+  if (pointer_to_zero_sized_aggr_p (TREE_TYPE (orig_op1)))
+    error_at (loc, "arithmetic on pointer to an empty aggregate");
+
   /* Divide by the size, in easiest possible way.  */
   result = fold_build2_loc (loc, EXACT_DIV_EXPR, inttype,
 			    op0, convert (inttype, op1));
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 2428204..aee3fcf 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2014-01-23  Marek Polacek  <polacek@redhat.com>
+
+	PR c/58346
+	* typeck.c (pointer_diff): Give an error on arithmetic on pointer to
+	an empty aggregate.
+
 2014-01-23  Jason Merrill  <jason@redhat.com>
 
 	PR c++/55189
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 84e287e..9cd6a95 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -5043,6 +5043,14 @@ pointer_diff (tree op0, tree op1, tree ptrtype, tsubst_flags_t complain)
 	return error_mark_node;
     }
 
+  if (pointer_to_zero_sized_aggr_p (TREE_TYPE (op1)))
+    {
+      if (complain & tf_error)
+	error ("arithmetic on pointer to an empty aggregate");
+      else
+	return error_mark_node;
+    }
+
   op1 = (TYPE_PTROB_P (ptrtype)
 	 ? size_in_bytes (target_type)
 	 : integer_one_node);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3857078..f3d8d3a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,12 @@
 2014-01-23  Marek Polacek  <polacek@redhat.com>
 
+	PR c/58346
+	* c-c++-common/pr58346-1.c: New test.
+	* c-c++-common/pr58346-2.c: New test.
+	* c-c++-common/pr58346-3.c: New test.
+
+2014-01-23  Marek Polacek  <polacek@redhat.com>
+
 	PR c/59871
 	* gcc.dg/20020220-2.c: Adjust dg-warning message.
 	* gcc.dg/pr59871.c: New test.
diff --git a/gcc/testsuite/c-c++-common/pr58346-1.c b/gcc/testsuite/c-c++-common/pr58346-1.c
new file mode 100644
index 0000000..371fcf4
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr58346-1.c
@@ -0,0 +1,24 @@
+/* PR c/58346 */
+/* { dg-do compile } */
+
+struct U {
+#ifdef __cplusplus
+  char a[0];
+#endif
+};
+static struct U b[6];
+static struct U *u1, *u2;
+
+int
+foo (struct U *p, struct U *q)
+{
+  return q - p; /* { dg-error "arithmetic on pointer to an empty aggregate" } */
+}
+
+void
+bar (void)
+{
+  __PTRDIFF_TYPE__ d = u1 - u2; /* { dg-error "arithmetic on pointer to an empty aggregate" } */
+  __asm volatile ("" : "+g" (d));
+  foo (&b[0], &b[4]);
+}
diff --git a/gcc/testsuite/c-c++-common/pr58346-2.c b/gcc/testsuite/c-c++-common/pr58346-2.c
new file mode 100644
index 0000000..195060e
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr58346-2.c
@@ -0,0 +1,8 @@
+/* PR c/58346 */
+/* { dg-do compile } */
+
+__PTRDIFF_TYPE__
+foo (int p[3][0], int q[3][0])
+{
+  return p - q; /* { dg-error "arithmetic on pointer to an empty aggregate" } */
+}
diff --git a/gcc/testsuite/c-c++-common/pr58346-3.c b/gcc/testsuite/c-c++-common/pr58346-3.c
new file mode 100644
index 0000000..41627ed
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr58346-3.c
@@ -0,0 +1,16 @@
+/* PR c/58346 */
+/* { dg-do compile } */
+
+void
+foo (void)
+{
+  __PTRDIFF_TYPE__ d;
+  const int i = 0;
+  int a1[2][0], a2[2][0];
+  int b1[3][i], b2[4][i];
+  d = a1 - a2; /* { dg-error "arithmetic on pointer to an empty aggregate" } */
+  __asm volatile ("" : "+g" (d));
+  /* No error here for C.  */
+  d = b1 - b2; /* { dg-error "arithmetic on pointer to an empty aggregate" "" { target c++ } } */
+  __asm volatile ("" : "+g" (d));
+}