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List:       gdb-cvs
Subject:    [binutils-gdb] [gdb/build] Fix C inclusion of nat/x86-cpuid.h
From:       Tom de Vries via Gdb-cvs <gdb-cvs () sourceware ! org>
Date:       2023-08-29 20:40:11
Message-ID: 20230829204011.B7CF53858409 () sourceware ! org
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https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=97319ac805eda5ade08b88651bb7490089a7781f

commit 97319ac805eda5ade08b88651bb7490089a7781f
Author: Tom de Vries <tdevries@suse.de>
Date:   Tue Aug 29 22:40:36 2023 +0200

    [gdb/build] Fix C inclusion of nat/x86-cpuid.h
    
    When running test-case gdb.arch/i386-avx512.exp, I run into:
    ...
     gdb compile failed, In file included from gdb.arch/i386-avx512.c:20:0:
     src/gdb/nat/x86-cpuid.h: In function 'x86_cpuid_count':
     src/gdb/nat/x86-cpuid.h:63:16: error: \
       'nullptr' undeclared (first use in this function)
        if (__eax == nullptr)
                     ^~~~~~~
     src/gdb/nat/x86-cpuid.h:63:16: note: each \
       undeclared identifier is reported only once for each function it appears in
    
                      === gdb Summary ===
    
     # of untested testcases         1
    ...
    
    This is due to commit e85aad4ae76 ("nat/x86-cpuid.h: Add x86_cpuid_count
    wrapper around __get_cpuid_count"), which introduced the nullptr check.
    
    The header file gdb/nat/x86-cpuid.h is a file that is included in the build
    and compiled as a C++ file, but also in the testsuite and compiled as a C
    file.
    
    Fix this by replacing nullptr with (void *)0.
    
    Tested on x86_64-linux.
    
    Co-Authored-By: Kevin Buettner <kevinb@redhat.com>
    Approved-by: Kevin Buettner <kevinb@redhat.com>

Diff:
---
 gdb/nat/x86-cpuid.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/gdb/nat/x86-cpuid.h b/gdb/nat/x86-cpuid.h
index 517113d45e8..e1b0321d593 100644
--- a/gdb/nat/x86-cpuid.h
+++ b/gdb/nat/x86-cpuid.h
@@ -22,6 +22,12 @@
 /* Always include the header for the cpu bit defines.  */
 #include "x86-gcc-cpuid.h"
 
+#ifndef __cplusplus
+/* This header file is also used in C code for some test-cases, so define
+   nullptr in C terms to avoid a compilation error.  */
+#define nullptr ((void *) 0)
+#endif
+
 #if defined(__i386__) || defined(__x86_64__)
 
 /* Return cpuid data for requested cpuid level, as found in returned
@@ -92,4 +98,10 @@ x86_cpuid_count (unsigned int __level, unsigned int __sublevel,
 
 #endif /* i386 && x86_64 */
 
+#ifndef __cplusplus
+/* Avoid leaking this local definition beyond the scope of this header
+   file.  */
+#undef nullptr
+#endif
+
 #endif /* NAT_X86_CPUID_H */
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