[LLVMbugs] [Bug 6976] New: autoconf test for <stdbool.h> fails

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=6976

           Summary: autoconf test for <stdbool.h> fails
           Product: clang
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Headers
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: pipping.elias at gmail.com
                CC: llvmbugs at cs.uiuc.edu


Here's the error:

conftest.c:84:16: error: initializer element is not a compile-time constant
         int xlcbug = 1 / (&(digs + 5)[-2 + (bool) 1] == &digs[4] ? 1 : -1);

here's where it comes from:


configure: failed program was:
| /* confdefs.h */
| #define PACKAGE_NAME "strace"
| #define PACKAGE_TARNAME "strace"
| #define PACKAGE_VERSION "4.5.20"
| #define PACKAGE_STRING "strace 4.5.20"
| #define PACKAGE_BUGREPORT ""
| #define PACKAGE_URL ""
| #define PACKAGE "strace"
| #define VERSION "4.5.20"
| #define LINUX 1
| #define X86_64 1
| #define STDC_HEADERS 1
| #define HAVE_SYS_TYPES_H 1
| #define HAVE_SYS_STAT_H 1
| #define HAVE_STDLIB_H 1
| #define HAVE_STRING_H 1
| #define HAVE_MEMORY_H 1
| #define HAVE_STRINGS_H 1
| #define HAVE_INTTYPES_H 1
| #define HAVE_STDINT_H 1
| #define HAVE_UNISTD_H 1
| #define __EXTENSIONS__ 1
| #define _ALL_SOURCE 1
| #define _GNU_SOURCE 1
| #define _POSIX_PTHREAD_SEMANTICS 1
| #define _TANDEM_SOURCE 1
| #define STDC_HEADERS 1
| /* end 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: true 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];
|       enum { j = false, k = true, l = false * true, m = true * 256 };
|       /* The following fails for
|          HP aC++/ANSI C B3910B A.05.55 [Dec 04 2003]. */
|       _Bool n[m];
|       char o[sizeof n == m * sizeof n[0] ? 1 : -1];
|       char p[-1 - (_Bool) 0 < 0 && -1 - (bool) 0 < 0 ? 1 : -1];
| #     if defined __xlc__ || defined __GNUC__
|        /* Catch a bug in IBM AIX xlc compiler version 6.0.0.0
|           reported by James Lemley on 2005-10-05; see
|          
http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html
|           This test is not quite right, since xlc is allowed to
|           reject this program, as the initializer for xlcbug is
|           not one of the forms that C requires support for.
|           However, doing the test right would require a runtime
|           test, and that would make cross-compilation harder.
|           Let us hope that IBM fixes the xlc bug, and also adds
|           support for this kind of constant expression.  In the
|           meantime, this test will reject xlc, which is OK, since
|           our stdbool.h substitute should suffice.  We also test
|           this with GCC, where it should work, to detect more
|           quickly whether someone messes up the test in the
|           future.  */
|        char digs[] = "0123456789";
|        int xlcbug = 1 / (&(digs + 5)[-2 + (bool) 1] == &digs[4] ? 1 : -1);
| #     endif
|       /* Catch a bug in an HP-UX C compiler.  See
|          http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html

|         
http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
|        */
|       _Bool q = true;
|       _Bool *pq = &q;
| 
| int
| main ()
| {
| 
|       *pq |= q;
|       *pq |= ! q;
|       /* Refer to every declared value, to avoid compiler optimizations.  */
|       return (!a + !b + !c + !d + !e + !f + !g + !h + !i + !!j + !k + !!l
|               + !m + !n + !o + !p + !q + !pq);
| 
|   ;
|   return 0;
| }

I'm not sure who's at fault here. This does mean that clang can't compile
strace right away, though, because configure (generated by autoconf 2.65)
considers clang's <stdbool.h> useless and the type bool is used in the code
(albeit for exactly one variable).

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