C2x has changed the expansions of the true and false macros in
<stdbool.h> so that they have type _Bool (including in #if conditions,
i.e. an unsigned type in that context). Use the new expansions in
GCC's <stdbool.h> for C2x.
See bug 82272 for related discussion (but this patch does *not*
implement the warning discussed there).
Note that it's possible there may be a further change to make bool,
true and false keywords (there was support in principle for that at
the April WG14 meeting). But currently these expansions of type _Bool
are what C2x requires and there isn't actually a paper before WG14 at
present that would introduce the new keywords.
Bootstrapped with no regressions on x86_64-pc-linux-gnu. OK to
commit?
gcc/
2020-10-28 Joseph Myers <jos...@codesourcery.com>
* ginclude/stdbool.c [__STDC_VERSION__ > 201710L] (true, false):
Define with type _Bool.
gcc/testsuite/
2020-10-28 Joseph Myers <jos...@codesourcery.com>
* gcc.dg/c11-bool-1.c, gcc.dg/c2x-bool-1.c, gcc.dg/c99-bool-4.c:
New tests.
diff --git a/gcc/ginclude/stdbool.h b/gcc/ginclude/stdbool.h
index 1b56498d96f..23554223d67 100644
--- a/gcc/ginclude/stdbool.h
+++ b/gcc/ginclude/stdbool.h
@@ -31,8 +31,13 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If
not, see
#ifndef __cplusplus
#define bool _Bool
+#if defined __STDC_VERSION__ && __STDC_VERSION__ > 201710L
+#define true ((_Bool)+1u)
+#define false ((_Bool)+0u)
+#else
#define true 1
#define false 0
+#endif
#else /* __cplusplus */
diff --git a/gcc/testsuite/gcc.dg/c11-bool-1.c
b/gcc/testsuite/gcc.dg/c11-bool-1.c
new file mode 100644
index 00000000000..0412624a706
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c11-bool-1.c
@@ -0,0 +1,50 @@
+/* Test macro expansions in <stdbool.h> in C11. */
+/* { dg-do run } */
+/* { dg-options "-std=c11 -pedantic-errors" } */
+
+#include <stdbool.h>
+
+#define str(x) xstr(x)
+#define xstr(x) #x
+
+extern void abort (void);
+extern void exit (int);
+extern int strcmp (const char *, const char *);
+
+#if false - 1 >= 0
+#error "false unsigned in #if"
+#endif
+
+#if false != 0
+#error "false not 0 in #if"
+#endif
+
+#if true - 2 >= 0
+#error "true unsigned in #if"
+#endif
+
+#if true != 1
+#error "true not 1 in #if"
+#endif
+
+int
+main (void)
+{
+ if (strcmp (str (bool), "_Bool") != 0)
+ abort ();
+ if (_Generic (true, int : 1) != 1)
+ abort ();
+ if (true != 1)
+ abort ();
+ if (strcmp (str (true), "1") != 0)
+ abort ();
+ if (_Generic (false, int : 1) != 1)
+ abort ();
+ if (false != 0)
+ abort ();
+ if (strcmp (str (false), "0") != 0)
+ abort ();
+ if (strcmp (str (__bool_true_false_are_defined), "1") != 0)
+ abort ();
+ exit (0);
+}
diff --git a/gcc/testsuite/gcc.dg/c2x-bool-1.c
b/gcc/testsuite/gcc.dg/c2x-bool-1.c
new file mode 100644
index 00000000000..b64da1f7b43
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-bool-1.c
@@ -0,0 +1,50 @@
+/* Test macro expansions in <stdbool.h> in C2x. */
+/* { dg-do run } */
+/* { dg-options "-std=c2x -pedantic-errors" } */
+
+#include <stdbool.h>
+
+#define str(x) xstr(x)
+#define xstr(x) #x
+
+extern void abort (void);
+extern void exit (int);
+extern int strcmp (const char *, const char *);
+
+#if false - 1 < 0
+#error "false signed in #if"
+#endif
+
+#if false != 0
+#error "false not 0 in #if"
+#endif
+
+#if true - 2 < 0
+#error "true signed in #if"
+#endif
+
+#if true != 1
+#error "true not 1 in #if"
+#endif
+
+int
+main (void)
+{
+ if (strcmp (str (bool), "_Bool") != 0)
+ abort ();
+ if (_Generic (true, _Bool : 1) != 1)
+ abort ();
+ if (true != 1)
+ abort ();
+ if (strcmp (str (true), "((_Bool)+1u)") != 0)
+ abort ();
+ if (_Generic (false, _Bool : 1) != 1)
+ abort ();
+ if (false != 0)
+ abort ();
+ if (strcmp (str (false), "((_Bool)+0u)") != 0)
+ abort ();
+ if (strcmp (str (__bool_true_false_are_defined), "1") != 0)
+ abort ();
+ exit (0);
+}
diff --git a/gcc/testsuite/gcc.dg/c99-bool-4.c
b/gcc/testsuite/gcc.dg/c99-bool-4.c
new file mode 100644
index 00000000000..5cae18ad0ce
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c99-bool-4.c
@@ -0,0 +1,46 @@
+/* Test macro expansions in <stdbool.h> in C99. */
+/* { dg-do run } */
+/* { dg-options "-std=c99 -pedantic-errors" } */
+
+#include <stdbool.h>
+
+#define str(x) xstr(x)
+#define xstr(x) #x
+
+extern void abort (void);
+extern void exit (int);
+extern int strcmp (const char *, const char *);
+
+#if false - 1 >= 0
+#error "false unsigned in #if"
+#endif
+
+#if false != 0
+#error "false not 0 in #if"
+#endif
+
+#if true - 2 >= 0
+#error "true unsigned in #if"
+#endif
+
+#if true != 1
+#error "true not 1 in #if"
+#endif
+
+int
+main (void)
+{
+ if (strcmp (str (bool), "_Bool") != 0)
+ abort ();
+ if (true != 1)
+ abort ();
+ if (strcmp (str (true), "1") != 0)
+ abort ();
+ if (false != 0)
+ abort ();
+ if (strcmp (str (false), "0") != 0)
+ abort ();
+ if (strcmp (str (__bool_true_false_are_defined), "1") != 0)
+ abort ();
+ exit (0);
+}
--
Joseph S. Myers
jos...@codesourcery.com
