[clang-tidy] Fix a crash in bugprone-not-null-terminated-result check when `__STDC_WANT_LIB_EXT1__` was undefined after definition.
PP->getMacroInfo() returns nullptr for undefined macro, so we need to check this return value before dereference.
Stack dump:
```
#0 0x0000000002185e6a llvm::sys::PrintStackTrace(llvm::raw_ostream&) (/llvm-project/build/bin/clang-tidy+0x2185e6a)
#1 0x0000000002183e8c llvm::sys::RunSignalHandlers() (/llvm-project/build/bin/clang-tidy+0x2183e8c)
#2 0x0000000002183ff3 SignalHandler(int) (/llvm-project/build/bin/clang-tidy+0x2183ff3)
#3 0x00007f37df9b1390 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x11390)
#4 0x000000000052054e clang::tidy::bugprone::NotNullTerminatedResultCheck::check(clang::ast_matchers::MatchFinder::MatchResult const&) (/llvm-project/build/bin/clang-tidy+0x52054e)
```
Reviewed By: hokein
Differential Revision: https://reviews.llvm.org/D85523
diff --git a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
index 269d69c..7d484d7 100644
--- a/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
@@ -802,11 +802,14 @@
while (It != PP->macro_end() && !AreSafeFunctionsWanted.hasValue()) {
if (It->first->getName() == "__STDC_WANT_LIB_EXT1__") {
const auto *MI = PP->getMacroInfo(It->first);
- const auto &T = MI->tokens().back();
- StringRef ValueStr = StringRef(T.getLiteralData(), T.getLength());
- llvm::APInt IntValue;
- ValueStr.getAsInteger(10, IntValue);
- AreSafeFunctionsWanted = IntValue.getZExtValue();
+ // PP->getMacroInfo() returns nullptr if macro has no definition.
+ if (MI) {
+ const auto &T = MI->tokens().back();
+ StringRef ValueStr = StringRef(T.getLiteralData(), T.getLength());
+ llvm::APInt IntValue;
+ ValueStr.getAsInteger(10, IntValue);
+ AreSafeFunctionsWanted = IntValue.getZExtValue();
+ }
}
++It;