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authorSimon Marchi <simon.marchi@polymtl.ca>2020-04-27 09:19:48 -0400
committerSimon Marchi <simon.marchi@efficios.com>2020-04-27 09:28:03 -0400
commitff8885c3be6f42ed90a7b0ec0028fad26861cd94 (patch)
tree419f5a2ef886df5232c07ea1dc38deee0c15244d /gdbsupport
parent991a3e2e9944a4b3a27bd989ac03c18285bd545d (diff)
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gdbsupport: include cstdlib in common-defs.h
In PR 25731 [1], the following build failure was reported: ../../binutils-gdb/gdb/gdbtypes.c:1254:10: error: no member named 'abs' in namespace 'std'; did you mean simply 'abs'? = ((std::abs (stride) * element_count) + 7) / 8; ^~~~~~~~ abs /usr/include/stdlib.h:129:6: note: 'abs' declared here int abs(int) __pure2; ^ The original report was using: $ gcc -v Apple LLVM version 8.0.0 (clang-800.0.42.1) Target: x86_64-apple-darwin15.6.0 Note that I was _not_ able to reproduce using: $ g++ --version Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/4.2.1 Apple clang version 11.0.0 (clang-1100.0.33.17) Target: x86_64-apple-darwin19.3.0 The proposed fix is to include <cstdlib> in addition to <stdlib.h>. Here's an excerpt of [2] relevant to this problem: These headers [speaking of the .h form] are allowed to also declare the same names in the std namespace, and the corresponding cxxx headers are allowed to also declare the same names in the global namespace: including <cstdlib> definitely provides std::malloc and may also provide ::malloc. Including <stdlib.h> definitely provides ::malloc and may also provide std::malloc Since we use std::abs, we should not assume that our include of stdlib.h declares an `abs` function in the `std` namespace. If we replace the include of stdlib.h with cstdlib, then we fall in the opposite situation. A standard C++ library may decide to only put the declarations in the std namespace, requiring us to prefix all standard functions with `std::`. I'm not against that, but for the moment I think the safest way forward is to just include both. Note that I don't know what effect this patch can have on any stdlib.h fix provided by gnulib. [1] https://sourceware.org/bugzilla/show_bug.cgi?id=25731 [2] https://en.cppreference.com/w/cpp/header#C_compatibility_headers gdbsupport/ChangeLog: * common-defs.h: Include cstdlib.h.
Diffstat (limited to 'gdbsupport')
-rw-r--r--gdbsupport/ChangeLog4
-rw-r--r--gdbsupport/common-defs.h5
2 files changed, 9 insertions, 0 deletions
diff --git a/gdbsupport/ChangeLog b/gdbsupport/ChangeLog
index 78fbbe6..b071049 100644
--- a/gdbsupport/ChangeLog
+++ b/gdbsupport/ChangeLog
@@ -1,3 +1,7 @@
+2020-04-27 Simon Marchi <simon.marchi@polymtl.ca>
+
+ * common-defs.h: Include cstdlib.h.
+
2020-04-20 Tom Tromey <tromey@adacore.com>
* scoped_mmap.h (scoped_mmap): Mark move constructor as noexcept.
diff --git a/gdbsupport/common-defs.h b/gdbsupport/common-defs.h
index e42d2b8..d3f5eaf 100644
--- a/gdbsupport/common-defs.h
+++ b/gdbsupport/common-defs.h
@@ -84,7 +84,12 @@
#include <stdarg.h>
#include <stdio.h>
+
+/* Include both cstdlib and stdlib.h to ensure we have standard functions
+ defined both in the std:: namespace and in the global namespace. */
+#include <cstdlib>
#include <stdlib.h>
+
#include <stddef.h>
#include <stdint.h>
#include <string.h>