c: Add -Wpedantic diagnostic for _Countof [PR117025]

It has been standardized in C2y.

	PR c/117025

gcc/c/ChangeLog:

	* c-parser.cc (c_parser_sizeof_or_countof_expression):
	Add -Wpedantic diagnostic for _Countof in <= C23 mode.

gcc/testsuite/ChangeLog:

	* gcc.dg/countof-compat.c: New test.
	* gcc.dg/countof-no-compat.c: New test.
	* gcc.dg/countof-pedantic.c: New test.
	* gcc.dg/countof-pedantic-errors.c: New test.

Signed-off-by: Alejandro Colomar <alx@kernel.org>

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 733cb312341e57c1cb8b7854f7c713052909854c..98a0c5632805f143fd11b0819440614c217d4bf6 100644 (file)
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -10649,6 +10649,10 @@ c_parser_sizeof_or_countof_expression (c_parser *parser, enum rid rid)
 
   start = c_parser_peek_token (parser)->location;
 
+  if (rid == RID_COUNTOF)
+    pedwarn_c23 (start, OPT_Wpedantic,
+                "ISO C does not support %qs before C23", op_name);
+
   c_parser_consume_token (parser);
   c_inhibit_evaluation_warnings++;
   if (rid == RID_COUNTOF)

diff --git a/gcc/testsuite/gcc.dg/countof-compat.c b/gcc/testsuite/gcc.dg/countof-compat.c
new file mode 100644 (file)
index 0000000..ab5b4ae
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/countof-compat.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c2y -pedantic-errors -Wc23-c2y-compat" } */
+
+#include <stdcountof.h>
+
+int a[1];
+int b[countof(a)];
+int c[_Countof(a)];  /* { dg-warning "ISO C does not support" } */

diff --git a/gcc/testsuite/gcc.dg/countof-no-compat.c b/gcc/testsuite/gcc.dg/countof-no-compat.c
new file mode 100644 (file)
index 0000000..4a244cf
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/countof-no-compat.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c23 -pedantic-errors -Wno-c23-c2y-compat" } */
+
+int a[1];
+int b[_Countof(a)];

diff --git a/gcc/testsuite/gcc.dg/countof-pedantic-errors.c b/gcc/testsuite/gcc.dg/countof-pedantic-errors.c
new file mode 100644 (file)
index 0000000..5d5bedb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/countof-pedantic-errors.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c23 -pedantic-errors" } */
+
+#include <stdcountof.h>
+
+int a[1];
+int b[countof(a)];
+int c[_Countof(a)];  /* { dg-error "ISO C does not support" } */

diff --git a/gcc/testsuite/gcc.dg/countof-pedantic.c b/gcc/testsuite/gcc.dg/countof-pedantic.c
new file mode 100644 (file)
index 0000000..408dc6f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/countof-pedantic.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c23 -pedantic" } */
+
+#include <stdcountof.h>
+
+int a[1];
+int b[countof(a)];
+int c[_Countof(a)];  /* { dg-warning "ISO C does not support" } */