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[v2,01/14] git-compat-util: introduce macros to disable "-Wsign-compare" warnings

Message ID 20241202-pks-sign-compare-v2-1-e7f0ad92a749@pks.im (mailing list archive)
State Superseded
Headers show
Series Start compiling with `-Wsign-compare` | expand

Commit Message

Patrick Steinhardt Dec. 2, 2024, 12:04 p.m. UTC 
When compiling with DEVELOPER=YesPlease, we explicitly disable the
"-Wsign-compare" warning. This is mostly because our code base is full
of cases where we don't bother at all whether something should be signed
or unsigned, and enabling the warning would thus cause tons of warnings
to pop up.

Unfortunately, disabling this warning also masks real issues. There have
been multiple CVEs in the Git project that would have been flagged by
this warning (e.g. CVE-2022-39260, CVE-2022-41903 and several fixes in
the vicinity of these CVEs). Furthermore, the final audit report by
X41 D-Sec, who are the ones who have discovered some of the CVEs, hinted
that it might be a good idea to become more strict in this context.

Now simply enabling the warning globally does not fly due to the stated
reason above that we simply have too many sites where we use the wrong
integer types. Instead, introduce a new set of macros that allow us to
mark a file as being free of warnings with "-Wsign-compare". The
mechanism is similar to what we do with `USE_THE_REPOSITORY_VARIABLE`:
every file that is not marked with `DISABLE_SIGN_COMPARE_WARNINGS` will
be compiled with those warnings enabled.

These new markings will be wired up in the subsequent commits.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 git-compat-util.h | 10 ++++++++++
 1 file changed, 10 insertions(+)
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Patch

diff --git a/git-compat-util.h b/git-compat-util.h
index e4a306dd5639b58a4ec4d2a6269fb649348fb4e7..31a059820f3b1536a3c1a887390b70098a6fbd09 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -44,6 +44,16 @@  struct strbuf;
  #define GIT_GNUC_PREREQ(maj, min) 0
 #endif
 
+#if defined(__GNUC__) || defined(__clang__)
+#  define PRAGMA(pragma)           _Pragma(#pragma)
+#  define DISABLE_WARNING(warning) PRAGMA(GCC diagnostic ignored #warning)
+#else
+#  define DISABLE_WARNING(warning)
+#endif
+
+#ifdef DISABLE_SIGN_COMPARE_WARNINGS
+DISABLE_WARNING(-Wsign-compare)
+#endif
 
 #ifndef FLEX_ARRAY
 /*