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| author | Nick Mathewson <nickm@torproject.org> | 2020-05-06 10:24:21 -0400 |
|---|---|---|
| committer | Nick Mathewson <nickm@torproject.org> | 2020-05-06 15:08:02 -0400 |
| commit | 6c3c94357c196681ceda773425e18161da8cfdef (patch) | |
| tree | 5c16d080bf7eee8438aaf702a57c1d61fb1eb3dc | |
| parent | d380acaecad5f554f7294cfcd7fbf100f9bbaca3 (diff) | |
| download | tor-6c3c94357c196681ceda773425e18161da8cfdef.tar.gz tor-6c3c94357c196681ceda773425e18161da8cfdef.zip | |
Add a fallthrough macro.
This macro defers to __attribute__((fallthrough)) on GCC (and
clang). Previously we had been using GCC's magic /* fallthrough */
comments, but clang very sensibly doesn't accept those.
Since not all compiler recognize it, we only define it when our
configure script detects that it works.
Part of a fix for 34078.
| -rw-r--r-- | configure.ac | 16 | ||||
| -rw-r--r-- | src/lib/cc/compat_compiler.h | 6 |
2 files changed, 22 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac index bc434ed836..a441162f4c 100644 --- a/configure.ac +++ b/configure.ac @@ -356,6 +356,22 @@ if test "$tor_cv_c_c99_designated_init" != "yes"; then AC_MSG_ERROR([Your compiler doesn't support c99 designated initializers. This is required as of Tor 0.2.6.x]) fi +saved_CFLAGS="$CFLAGS" +CFLAGS="$CFLAGS -Werror" +AC_CACHE_CHECK([for __attribute__((fallthrough))], + tor_cv_c_attr_fallthrough, + [AC_COMPILE_IFELSE( + [AC_LANG_PROGRAM([extern int x; void fn(void) ;], + [[ switch (x) { case 1: fn(); __attribute__((fallthrough)); + case 2: fn(); break; } ]])], + [tor_cv_c_attr_fallthrough=yes], + [tor_cv_c_attr_fallthrough=no] )]) +CFLAGS="$saved_CFLAGS" + +if test "$tor_cv_c_attr_fallthrough" == "yes"; then + AC_DEFINE(HAVE_ATTR_FALLTHROUGH, [1], [defined if we have the fallthrough attribute.]) +fi + TORUSER=_tor AC_ARG_WITH(tor-user, AS_HELP_STRING(--with-tor-user=NAME, [specify username for tor daemon]), diff --git a/src/lib/cc/compat_compiler.h b/src/lib/cc/compat_compiler.h index 3a0f307186..fbe6a38f1f 100644 --- a/src/lib/cc/compat_compiler.h +++ b/src/lib/cc/compat_compiler.h @@ -50,6 +50,12 @@ #define CHECK_SCANF(formatIdx, firstArg) #endif /* defined(__GNUC__) */ +#if defined(HAVE_ATTR_FALLTHROUGH) +#define FALLTHROUGH __attribute__((fallthrough)) +#else +#define FALLTHROUGH +#endif + /* What GCC do we have? */ #ifdef __GNUC__ #define GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__) |