[clang-tidy] Fix bugprone-bad-signal-to-kill-thread crash when `SIGTERM` is not a literal.

[ArcsinX]

Summary

If SIGTERM is not a literal (e.g. #define SIGTERM ((unsigned)15)) bugprone-bad-signal-to-kill-thread check crashes.
Stack dump:

#0 0x000000000217d15a llvm::sys::PrintStackTrace(llvm::raw_ostream&) (/llvm-project/build/bin/clang-tidy+0x217d15a)
#1 0x000000000217b17c llvm::sys::RunSignalHandlers() (/llvm-project/build/bin/clang-tidy+0x217b17c)
#2 0x000000000217b2e3 SignalHandler(int) (/llvm-project/build/bin/clang-tidy+0x217b2e3)
#3 0x00007f6a7efb1390 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x11390)
#4 0x000000000212ac9b llvm::StringRef::getAsInteger(unsigned int, llvm::APInt&) const (/llvm-project/build/bin/clang-tidy+0x212ac9b)
#5 0x0000000000593501 clang::tidy::bugprone::BadSignalToKillThreadCheck::check(clang::ast_matchers::MatchFinder::MatchResult const&) (/llvm-project/build/bin/clang-tidy+0x593501)

[hokein]

clang-tools-extra/test/clang-tidy/checkers/bugprone-bad-signal-to-kill-thread-sigterm-not-a-literal.cpp

1

the same here.

[ArcsinX]

Fix test according to review comment

[ArcsinX]

Thank you for review!

clang-tools-extra/test/clang-tidy/checkers/bugprone-bad-signal-to-kill-thread-sigterm-not-a-literal.cpp

1

Fixed

clang-tools-extra/clang-tidy/bugprone/BadSignalToKillThreadCheck.cpp

const auto IsSigterm = [](const auto &KeyValue) -> bool {
     return KeyValue.first->getName() == "SIGTERM";
   };
   const auto TryExpandAsInteger =
       [](Preprocessor::macro_iterator It) -> Optional<unsigned> {
     if (It == PP->macro_end())
       return llvm::None;
     const MacroInfo *MI = PP->getMacroInfo(It->first);
     const Token &T = MI->tokens().back();
+    if (!T.isLiteral())
+      return llvm::None;
     StringRef ValueStr = StringRef(T.getLiteralData(), T.getLength());
 
     llvm::APInt IntValue;
     constexpr unsigned AutoSenseRadix = 0;
     if (ValueStr.getAsInteger(AutoSenseRadix, IntValue))
       return llvm::None;
     return IntValue.getZExtValue();
   };

clang-tools-extra/test/clang-tidy/checkers/bugprone-bad-signal-to-kill-thread-sigterm-not-a-literal.cpp

+// RUN: clang-tidy %s --checks="-*,bugprone-bad-signal-to-kill-thread"
+
+#define SIGTERM ((unsigned)15) // no-crash
+using pthread_t = int;
+int pthread_kill(pthread_t thread, int sig);
+
+int func() {
+  pthread_t thread;
+  return pthread_kill(thread, 0);
+}