Here is a patch that adds the minor corrections needed for
qualifiers of pointers to arrays in C23.
-- Martin
C: Correct qualifiers for pointers to arrays according to C2X [PR98397]
2020-12-12 Martin Uecker <muec...@gwdg.de>
gcc/c/
PR c/98397
* c-typeck.c (comp_target_types): Change pedwarn to pedwarn_c11
for pointers to arrays with qualifiers.
(build_conditional_expr): For C23 don't lose qualifiers for pointers
to arrays when the other pointer is a void pointer.
(convert_for_assignment): For C23 don't pedwarn when converting from
void* with qualifiers to a pointer to array with the same qualifiers.
gcc/testsuite/
PR c/98397
* gcc.dg/c2x-qual-1.c: New test.
* gcc.dg/c2x-qual-2.c: New test.
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index f68cb01529b..46a66e96db5 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -1318,8 +1318,8 @@ comp_target_types (location_t location, tree ttl, tree
ttr)
val = comptypes_check_enum_int (mvl, mvr, &enum_and_int_p);
if (val == 1 && val_ped != 1)
- pedwarn (location, OPT_Wpedantic, "pointers to arrays with different
qualifiers "
- "are incompatible in ISO C");
+ pedwarn_c11 (location, OPT_Wpedantic, "pointers to arrays with different
qualifiers "
+ "are incompatible in ISO C before
C2X");
if (val == 2)
pedwarn (location, OPT_Wpedantic, "types are not quite compatible");
@@ -5331,39 +5331,32 @@ build_conditional_expr (location_t colon_loc, tree
ifexp, bool ifexp_bcp,
"used in conditional expression");
return error_mark_node;
}
- else if (VOID_TYPE_P (TREE_TYPE (type1))
- && !TYPE_ATOMIC (TREE_TYPE (type1)))
- {
- if ((TREE_CODE (TREE_TYPE (type2)) == ARRAY_TYPE)
- && (TYPE_QUALS (strip_array_types (TREE_TYPE (type2)))
- & ~TYPE_QUALS (TREE_TYPE (type1))))
+ else if ((VOID_TYPE_P (TREE_TYPE (type1))
+ && !TYPE_ATOMIC (TREE_TYPE (type1)))
+ || (VOID_TYPE_P (TREE_TYPE (type2))
+ && !TYPE_ATOMIC (TREE_TYPE (type2))))
+ {
+ tree t1 = TREE_TYPE (type1);
+ tree t2 = TREE_TYPE (type2);
+ if (!VOID_TYPE_P (t1))
+ {
+ /* roles are swapped */
+ t1 = t2;
+ t2 = TREE_TYPE (type1);
+ }
+ tree t2_stripped = strip_array_types (t2);
+ if (flag_isoc2x)
+ t2 = t2_stripped;
+ else if ((TREE_CODE (t2) == ARRAY_TYPE)
+ && (TYPE_QUALS (t2_stripped) & ~TYPE_QUALS (t1)))
warning_at (colon_loc, OPT_Wdiscarded_array_qualifiers,
"pointer to array loses qualifier "
"in conditional expression");
-
- if (TREE_CODE (TREE_TYPE (type2)) == FUNCTION_TYPE)
- pedwarn (colon_loc, OPT_Wpedantic,
- "ISO C forbids conditional expr between "
- "%<void *%> and function pointer");
- result_type = build_pointer_type (qualify_type (TREE_TYPE (type1),
- TREE_TYPE (type2)));
- }
- else if (VOID_TYPE_P (TREE_TYPE (type2))
- && !TYPE_ATOMIC (TREE_TYPE (type2)))
- {
- if ((TREE_CODE (TREE_TYPE (type1)) == ARRAY_TYPE)
- && (TYPE_QUALS (strip_array_types (TREE_TYPE (type1)))
- & ~TYPE_QUALS (TREE_TYPE (type2))))
- warning_at (colon_loc, OPT_Wdiscarded_array_qualifiers,
- "pointer to array loses qualifier "
- "in conditional expression");
-
- if (TREE_CODE (TREE_TYPE (type1)) == FUNCTION_TYPE)
+ if (TREE_CODE (t2) == FUNCTION_TYPE)
pedwarn (colon_loc, OPT_Wpedantic,
"ISO C forbids conditional expr between "
"%<void *%> and function pointer");
- result_type = build_pointer_type (qualify_type (TREE_TYPE (type2),
- TREE_TYPE (type1)));
+ result_type = build_pointer_type (qualify_type (t1, t2));
}
/* Objective-C pointer comparisons are a bit more lenient. */
else if (objc_have_common_type (type1, type2, -3, NULL_TREE))
@@ -7319,7 +7312,7 @@ convert_for_assignment (location_t location, location_t
expr_loc, tree type,
/* Don't warn about loss of qualifier for conversions from
qualified void* to pointers to arrays with corresponding
qualifier on the element type. */
- if (!pedantic)
+ if (flag_isoc2x || !pedantic)
ttl = strip_array_types (ttl);
/* Assignments between atomic and non-atomic objects are OK. */
diff --git a/gcc/testsuite/gcc.dg/c2x-qual-1.c
b/gcc/testsuite/gcc.dg/c2x-qual-1.c
new file mode 100644
index 00000000000..058a840e04c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-qual-1.c
@@ -0,0 +1,12 @@
+/* Test that qualifiers are not lost in tertiary operator for pointers to
arrays, PR98397 */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu2x" } */
+
+void foo(void)
+{
+ const int (*u)[1];
+ void *v;
+ extern const void *vc;
+ extern typeof(1 ? u : v) vc;
+ extern typeof(1 ? v : u) vc;
+}
diff --git a/gcc/testsuite/gcc.dg/c2x-qual-2.c
b/gcc/testsuite/gcc.dg/c2x-qual-2.c
new file mode 100644
index 00000000000..68b897226d3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-qual-2.c
@@ -0,0 +1,12 @@
+/* Test that there are no warnings about lost qualifiers for pointers to arrays
+ with pedantic for C2X, PR98397 */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu2x -pedantic" } */
+
+void foo(void)
+{
+ const void *w;
+ const int (*u)[1] = w;
+ void *v;
+ (1 ? u : v);
+}
