[flang] Avoid forming a reference from null pointer #84787
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Doing so is an undefined behavior. This was detected by the undefined behavior sanitizer.
llvmbot
added
flang
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@llvm/pr-subscribers-flang-parser Author: Krzysztof Parzyszek (kparzysz) ChangesDoing so is an undefined behavior. This was detected by the undefined behavior sanitizer. Full diff: https://github.com/llvm/llvm-project/pull/84787.diff 1 Files Affected:
diff --git a/flang/lib/Parser/token-sequence.cpp b/flang/lib/Parser/token-sequence.cpp
index c5a630c471d16e..a53205b35f0761 100644
--- a/flang/lib/Parser/token-sequence.cpp
+++ b/flang/lib/Parser/token-sequence.cpp
@@ -136,7 +136,10 @@ void TokenSequence::Put(
}
void TokenSequence::Put(const CharBlock &t, Provenance provenance) {
- Put(&t[0], t.size(), provenance);
+ // Avoid t[0] if t is empty: it would create a reference to nullptr,
+ // which is UB.
+ const char *addr = t.size() ? &t[0] : nullptr;
+ Put(addr, t.size(), provenance);
}
void TokenSequence::Put(const std::string &s, Provenance provenance) {
|
klausler
requested changes
Mar 11, 2024
flang/lib/Parser/token-sequence.cpp
Outdated
| Put(&t[0], t.size(), provenance); | ||
| // Avoid t[0] if t is empty: it would create a reference to nullptr, | ||
| // which is UB. | ||
| const char *addr = t.size() ? &t[0] : nullptr; |
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Use braced initialization in Flang front-end code.
klausler
approved these changes
Mar 11, 2024
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Doing so is an undefined behavior.
This was detected by the undefined behavior sanitizer.