[clang] 26f5d1e - [APINotes] Avoid assertion failure with expensive checks (#120487)

[via cfe-commits]

Author: Björn Pettersson
Date: 2024-12-18T23:36:45+01:00
New Revision: 26f5d1ee9c37e2a6d50898a5bf2d3b9171060ba0

URL: https://github.com/llvm/llvm-project/commit/26f5d1ee9c37e2a6d50898a5bf2d3b9171060ba0
DIFF: https://github.com/llvm/llvm-project/commit/26f5d1ee9c37e2a6d50898a5bf2d3b9171060ba0.diff

LOG: [APINotes] Avoid assertion failure with expensive checks (#120487)

Found assertion failures when using EXPENSIVE_CHECKS and running lit
tests for APINotes:
Assertion `left.first != right.first && "two entries for the same
version"' failed.

It seems like std::is_sorted is verifying that the comparison function
is reflective (comp(a,a)=false) when using expensive checks. So we would
get callbacks to the lambda used for comparison, even for vectors with a
single element in APINotesReader::VersionedInfo<T>::VersionedInfo, with
"left" and "right" being the same object. Therefore the assert checking
that we never found equal values would fail.

Fix makes sure that we skip the check for equal values when "left" and
"right" is the same object.

Added: 
    

Modified: 
    clang/lib/APINotes/APINotesReader.cpp

Removed: 
    


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diff  --git a/clang/lib/APINotes/APINotesReader.cpp b/clang/lib/APINotes/APINotesReader.cpp
index fa06dffdd14b03..646eabd2a5ecd3 100644
--- a/clang/lib/APINotes/APINotesReader.cpp
+++ b/clang/lib/APINotes/APINotesReader.cpp
@@ -2045,7 +2045,12 @@ APINotesReader::VersionedInfo<T>::VersionedInfo(
       Results.begin(), Results.end(),
       [](const std::pair<llvm::VersionTuple, T> &left,
          const std::pair<llvm::VersionTuple, T> &right) -> bool {
-        assert(left.first != right.first && "two entries for the same version");
+        // The comparison function should be reflective, and with expensive
+        // checks we can get callbacks basically checking that lambda(a,a) is
+        // false. We could still check that we do not find equal elements when
+        // left!=right.
+        assert((&left == &right || left.first != right.first) &&
+               "two entries for the same version");
         return left.first < right.first;
       }));