Re: Bison uses two different 'bool' flavors

[Akim Demaille]

Akim:

| Paul: 
| | +AC_DEFUN([AC_HEADER_STDBOOL],
|
| How about installing this guy in Autoconf :)

I'm installing the following patch Paul.  There are a few changes:
AC_TRY_RUN is considered obsolete, and I believe we don't want to
indent the #directives.  I also trust #error is supported by any
compiler (I have never seen proofs of the opposite, just vague
memories) and certainly by compilers who are expected to have
stdbool.h.

Nevertheless I have a question: is it normal that it fails on my
machine?

| configure:2029: checking for stdbool.h that conforms to C99
| configure:2079: gcc -c -g -O2  conftest.c >&5
| configure:2038: #error bool is not defined
| configure:2050: #error true is not 1
| configure:2082: $? = 1
| configure: failed program was:
| #line 2034 "configure"
| #include "confdefs.h"
| 
| #include <stdbool.h>
| #ifndef bool
| # error bool is not defined
| #endif
| #ifndef false
| # error false is not defined
| #endif
| #if false
| # error false is not 0
| #endif
| #ifndef true
| # error false is not defined
| #endif
| #if true != 1
| # error true is not 1
| #endif
| #ifndef __bool_true_false_are_defined
| # error __bool_true_false_are_defined is not defined
| #endif
| 
|         struct s { _Bool s: 1; _Bool t; } s;
| 
|         char a[true == 1 ? 1 : -1];
|         char b[false == 0 ? 1 : -1];
|         char c[__bool_true_false_are_defined == 1 ? 1 : -1];
|         char d[(bool) -0.5 == true ? 1 : -1];
|         bool e = &s;
|         char f[(_Bool) -0.0 == false ? 1 : -1];
|         char g[true];
|         char h[sizeof (_Bool)];
|         char i[sizeof s.t];
| 
| int
| main ()
| {
|  return !a + !b + !c + !d + !e + !f + !g + !h + !i;
|   ;
|   return 0;
| }
| configure:2098: result: no

Here is the way it fails on Bison, i.e., *without* the #error:

| configure:4322: checking for stdbool.h that conforms to C99
| configure:4372: gcc -c -g -O2  conftest.c >&5
| configure:4331: parse error before string constant
| configure:4349: warning: data definition has no type or storage class
| configure:4349: warning: data definition has no type or storage class
| configure:4354: size of array `d' is negative
| configure:4355: incompatible types in initialization
| configure:4355: initializer element is not constant
| configure:4356: `_Bool' undeclared here (not in a function)
| configure:4358: `_Bool' undeclared here (not in a function)
| configure:4359: request for member `t' in something not a structure or union
| configure:4375: $? = 1
| configure: failed program was:
| #line 4327 "configure"
| #include "confdefs.h"
| 
|         #include <stdbool.h>
|         #ifndef bool
|          "error: bool is not defined"
|         #endif
|         #ifndef false
|          "error: false is not defined"
|         #endif
|         #if false
|          "error: false is not 0"
|         #endif
|         #ifndef true
|          "error: false is not defined"
|         #endif
|         #if true != 1
|          "error: true is not 1"
|         #endif
|         #ifndef __bool_true_false_are_defined
|          "error: __bool_true_false_are_defined is not defined"
|         #endif
| 
|         struct s { _Bool s: 1; _Bool t; } s;
| 
|         char a[true == 1 ? 1 : -1];
|         char b[false == 0 ? 1 : -1];
|         char c[__bool_true_false_are_defined == 1 ? 1 : -1];
|         char d[(bool) -0.5 == true ? 1 : -1];
|         bool e = &s;
|         char f[(_Bool) -0.0 == false ? 1 : -1];
|         char g[true];
|         char h[sizeof (_Bool)];
|         char i[sizeof s.t];
| 
| int
| main ()
| {
|  return !a + !b + !c + !d + !e + !f + !g + !h + !i;
|   ;
|   return 0;
| }
| configure:4391: result: no
| 


Anyway, here is the patch:

Index: ChangeLog
from  Akim Demaille  <address@hidden>

        * lib/autoconf/headers.m4 (AC_HEADER_STDBOOL): New, based on CVS
        Bison, by Paul Eggert.
        * doc/autoconf.texi (Particular Headers): Document it.

Index: NEWS
===================================================================
RCS file: /cvsroot/autoconf/autoconf/NEWS,v
retrieving revision 1.269
diff -u -u -r1.269 NEWS
--- NEWS 22 Oct 2002 12:18:46 -0000 1.269
+++ NEWS 22 Oct 2002 12:32:37 -0000
@@ -11,7 +11,7 @@
 ** Macros
 
 - New macros
-  AC_FUNC_MBRTOWC
+  AC_FUNC_MBRTOWC, AC_HEADER_STDBOOL.
 
 - Obsoleted
   Obsoleted macros are kept for Autoconf backward compatibility, but
Index: doc/autoconf.texi
===================================================================
RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
retrieving revision 1.691
diff -u -u -r1.691 autoconf.texi
--- doc/autoconf.texi 22 Oct 2002 12:13:21 -0000 1.691
+++ doc/autoconf.texi 22 Oct 2002 12:32:40 -0000
@@ -4281,6 +4281,22 @@
 Amdahl UTS and Motorola System V/88.
 @end defmac
 
address@hidden AC_HEADER_STDBOOL
address@hidden HEADER_STDBOOL
address@hidden HAVE_STDBOOL_H
+If @file{stdbool.h} exists and is conformant to C99, define
address@hidden to 1.  Your @file{system.h} should contain the
+following code:
+
address@hidden
+#if HAVE_STDBOOL_H
+# include <stdbool.h>
+#else
+typedef enum {false = 0, true = 1} bool;
+#endif
address@hidden verbatim
address@hidden defmac
+
 
 @defmac AC_HEADER_STDC
 @acindex HEADER_STDC
Index: lib/autoconf/headers.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/headers.m4,v
retrieving revision 1.24
diff -u -u -r1.24 headers.m4
--- lib/autoconf/headers.m4 22 Oct 2002 12:02:08 -0000 1.24
+++ lib/autoconf/headers.m4 22 Oct 2002 12:32:40 -0000
@@ -487,6 +487,58 @@
 ])# AC_HEADER_STAT
 
 
+# AC_HEADER_STDBOOL
+# -----------------
+# Check for stdbool.h that conforms to C99.
+AN_IDENTIFIER([bool], [AC_HEADER_STDBOOL])
+AN_IDENTIFIER([true], [AC_HEADER_STDBOOL])
+AN_IDENTIFIER([false],[AC_HEADER_STDBOOL])
+AC_DEFUN([AC_HEADER_STDBOOL],
+[AC_CACHE_CHECK([for stdbool.h that conforms to C99],
+   [ac_cv_header_stdbool_h],
+   [AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+      [[
+#include <stdbool.h>
+#ifndef bool
+# error bool is not defined
+#endif
+#ifndef false
+# error false is not defined
+#endif
+#if false
+# error false is not 0
+#endif
+#ifndef true
+# error false is not defined
+#endif
+#if true != 1
+# error true is not 1
+#endif
+#ifndef __bool_true_false_are_defined
+# error __bool_true_false_are_defined is not defined
+#endif
+
+        struct s { _Bool s: 1; _Bool t; } s;
+
+        char a[true == 1 ? 1 : -1];
+        char b[false == 0 ? 1 : -1];
+        char c[__bool_true_false_are_defined == 1 ? 1 : -1];
+        char d[(bool) -0.5 == true ? 1 : -1];
+        bool e = &s;
+        char f[(_Bool) -0.0 == false ? 1 : -1];
+        char g[true];
+        char h[sizeof (_Bool)];
+        char i[sizeof s.t];
+      ]],
+      [[ return !a + !b + !c + !d + !e + !f + !g + !h + !i; ]])],
+      [ac_cv_header_stdbool_h=yes],
+      [ac_cv_header_stdbool_h=no])])
+if test $ac_cv_header_stdbool_h = yes; then
+  AC_DEFINE(HAVE_STDBOOL_H, 1, [Define to 1 if stdbool.h conforms to C99.])
+fi
+])# AC_HEADER_STDBOOL
+
+
 # AC_HEADER_STDC
 # --------------
 # FIXME: I find this list very strange.  It comes from the original
Index: lib/autoscan/autoscan.list
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoscan/autoscan.list,v
retrieving revision 1.6
diff -u -u -r1.6 autoscan.list
--- lib/autoscan/autoscan.list 11 Oct 2002 12:17:52 -0000 1.6
+++ lib/autoscan/autoscan.list 22 Oct 2002 12:32:40 -0000
@@ -247,7 +247,9 @@
 identifier: S_ISLNK            AC_HEADER_STAT
 identifier: S_ISREG            AC_HEADER_STAT
 identifier: S_ISSOCK           AC_HEADER_STAT
+identifier: bool               AC_HEADER_STDBOOL
 identifier: const              AC_C_CONST
+identifier: false              AC_HEADER_STDBOOL
 identifier: gid_t              AC_TYPE_UID_T
 identifier: inline             AC_C_INLINE
 identifier: mode_t             AC_TYPE_MODE_T
@@ -263,6 +265,7 @@
 identifier: timeval            AC_HEADER_TIME
 identifier: tm         AC_STRUCT_TM
 identifier: tm_zone            AC_STRUCT_TIMEZONE
+identifier: true               AC_HEADER_STDBOOL
 identifier: uid_t              AC_TYPE_UID_T
 identifier: volatile           AC_C_VOLATILE
 makevar: AWK           AC_PROG_AWK