| Issue |
165238
|
| Summary |
[clang] Crash in `SemaConcept.cpp` / `Sema::getNormalizedAssociatedConstraints` (invalidated iterator?)
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
jiixyj
|
On 1322e71f2baac9d7cfa77cfa5345bfffbff74cf7 I'm getting a crash in `SemaConcept.cpp` when compiling some C++ code (this is a `RelWithDebInfo` build with assertions enabled):
```
#7 0x00007ff333c3eefc abort ./stdlib/abort.c:81:3
#8 0x00007ff333c3ee6a __assert_perror_fail ./assert/assert-perr.c:31:1
#9 0x000056107c5555ee llvm::DenseMapIterator<llvm::PointerUnion<clang::NamedDecl const*, clang::concepts::NestedRequirement const*>, clang::NormalizedConstraint*, llvm::DenseMapInfo<llvm::Poi
nterUnion<clang::NamedDecl const*, clang::concepts::NestedRequirement const*>, void>, llvm::detail::DenseMapPair<llvm::PointerUnion<clang::NamedDecl const*, clang::concepts::NestedRequirement
const*>, clang::NormalizedConstraint*>, false>::operator*() const /freebsd/data/linux/git-net/llvm-project/llvm/include/llvm/ADT/DenseMap.h:1217:5
#10 0x000056107c5555ee llvm::DenseMapIterator<llvm::PointerUnion<clang::NamedDecl const*, clang::concepts::NestedRequirement const*>, clang::NormalizedConstraint*, llvm::DenseMapInfo<llvm::Poi
nterUnion<clang::NamedDecl const*, clang::concepts::NestedRequirement const*>, void>, llvm::detail::DenseMapPair<llvm::PointerUnion<clang::NamedDecl const*, clang::concepts::NestedRequirement
const*>, clang::NormalizedConstraint*>, false>::operator->() const /freebsd/data/linux/git-net/llvm-project/llvm/include/llvm/ADT/DenseMap.h:1220:54
#11 0x000056107c5555ee clang::Sema::getNormalizedAssociatedConstraints(llvm::PointerUnion<clang::NamedDecl const*, clang::concepts::NestedRequirement const*>, llvm::ArrayRef<clang::AssociatedC
onstraint>) /freebsd/data/linux/git-net/llvm-project/clang/lib/Sema/SemaConcept.cpp:2419:10
#12 0x000056107c551812 CheckConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, llvm::ArrayRef<clang::AssociatedConstraint>, clang::MultiLevelTemplateArgumentList const&, clang::Sour
ceRange, clang::ConstraintSatisfaction&, clang::Expr**, clang::ConceptReference const*) /freebsd/data/linux/git-net/llvm-project/clang/lib/Sema/SemaConcept.cpp:1155:8
#13 0x000056107c551582 clang::Sema::CheckConstraintSatisfaction(llvm::PointerUnion<clang::NamedDecl const*, clang::concepts::NestedRequirement const*>, llvm::ArrayRef<clang::AssociatedConstrai
nt>, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&, clang::ConceptReference const*, clang::Expr**) /freebsd/data/linux/git-net/llvm-project/c
lang/lib/Sema/SemaConcept.cpp:1227:7
```
This comes from the line `return CacheEntry->second;`. It looks like this iterator gets invalidated, maybe by the earlier call `SubstituteParameterMappings(*this).substitute(*Normalized)`.
This works around the issue:
```patch
diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index f04cc454cdb7..8135e1bc239f 100644
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -2408,12 +2408,16 @@ const NormalizedConstraint *Sema::getNormalizedAssociatedConstraints(
if (CacheEntry == NormalizationCache.end()) {
auto *Normalized = NormalizedConstraint::fromAssociatedConstraints(
*this, ND, AssociatedConstraints);
- CacheEntry =
- NormalizationCache.try_emplace(ConstrainedDeclOrNestedReq, Normalized)
- .first;
+ auto [it, inserted] = NormalizationCache.try_emplace(ConstrainedDeclOrNestedReq, Normalized);
+ assert(inserted);
+ assert(it != NormalizationCache.end());
+
if (!Normalized ||
SubstituteParameterMappings(*this).substitute(*Normalized))
return nullptr;
+
+ CacheEntry = NormalizationCache.find(ConstrainedDeclOrNestedReq);
+ assert(CacheEntry != NormalizationCache.end());
}
return CacheEntry->second;
}
```
Would a minimal reproducer help? It's a bit difficult, because I'm using C++20 modules...
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