[clang-tidy] Fix crashes in bugprone-bad-signal-to-kill-thread check.

[ArcsinX]

Summary

This patch fixes crashes in the following cases:

• SIGTERM is not a literal
• SIGTERM is a literal but Token::PtrData == nullptr (happens in clangd, because clang-tidy in clangd has some limitations to ensure reasonable performance)
• SIGTERM undefined after definition

[hokein]

while this patch fixes multiple issues (as described in the message), I'd suggest splitting it.

[ArcsinX]

In D85301#2197263, @hokein wrote:

while this patch fixes multiple issues (as described in the message), I'd suggest splitting it.

Thanks for you suggestion.

SIGTERM is not a literal

D85398

SIGTERM is a literal but Token::PtrData == nullptr (happens in clangd, because clang-tidy in clangd has some limitations to ensure reasonable performance)

For this I will create after if/when previous one will be accepted. Seems it's more related to clangd then clang-tidy.

SIGTERM undefined after definition

D85401

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

Finder->addMatcher(
           .bind("thread-kill"),
       this);
 }
 
 static Preprocessor *PP;
 
 void BadSignalToKillThreadCheck::check(const MatchFinder::MatchResult &Result) {
   const auto IsSigterm = [](const auto &KeyValue) -> bool {
-    return KeyValue.first->getName() == "SIGTERM";
+    return KeyValue.first->getName() == "SIGTERM" &&
+           KeyValue.first->hasMacroDefinition();
   };
   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() || !T.getLiteralData())
+      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/clangd/unittests/DiagnosticsTests.cpp

Annotations Main(R"cpp(
     }
   )cpp");
   TestTU TU = TestTU::withCode(Main.code());
   TU.ClangTidyChecks = "bugprone-integer-division";
   TU.ClangTidyWarningsAsErrors = "bugprone-integer-division";
   EXPECT_THAT(TU.build().getDiagnostics(), UnorderedElementsAre());
 }
 
+TEST(DiagnosticTest, ClangTidyBadSignalToKillThread) {
+  Annotations Main(R"cpp(
+    #define SIGTERM 15
+    using pthread_t = int;
+    int pthread_kill(pthread_t thread, int sig);
+    int func() {
+      pthread_t thread;
+      return pthread_kill(thread, 0);
+    }
+  )cpp");
+  TestTU TU = TestTU::withCode(Main.code());
+  TU.ClangTidyChecks = "-*,bugprone-bad-signal-to-kill-thread";
+  EXPECT_THAT(TU.build().getDiagnostics(), UnorderedElementsAre()); // no-crash
+}
+
 TEST(DiagnosticsTest, Preprocessor) {
   // This looks like a preamble, but there's an #else in the middle!
   // Check that:
   //  - the #else doesn't generate diagnostics (we had this bug)
   //  - we get diagnostics from the taken branch
   //  - we get no diagnostics from the not taken branch
   Annotations Test(R"cpp(
     #ifndef FOO

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);
+}

clang-tools-extra/test/clang-tidy/checkers/bugprone-bad-signal-to-kill-thread-undef-sigterm.cpp

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