[clang] f0c7505 - [Clang] Fix the order of addInstantiatedParameters in LambdaScopeForCallOperatorInstantiationRAII (#97215)
via cfe-commits
cfe-commits at lists.llvm.org
Tue Jul 9 01:39:53 PDT 2024
Author: Yupei Liu
Date: 2024-07-09T16:39:50+08:00
New Revision: f0c7505f597998c84023ccd609ecfc9af3d5b4d6
URL: https://github.com/llvm/llvm-project/commit/f0c7505f597998c84023ccd609ecfc9af3d5b4d6
DIFF: https://github.com/llvm/llvm-project/commit/f0c7505f597998c84023ccd609ecfc9af3d5b4d6.diff
LOG: [Clang] Fix the order of addInstantiatedParameters in LambdaScopeForCallOperatorInstantiationRAII (#97215)
Currently, `addInstantiatedParameters` is called from the innermost
lambda outward. However, when the function parameters of an inner lambda
depend on the function parameters of an outer lambda, it can lead to a
crash due to the inability to find a mapping for the instantiated decl.
This PR corrects this behavior by calling `addInstantiatedParameters`
from the outside in.
repro code: https://godbolt.org/z/KbsxWesW6
```cpp
namespace dependent_param_concept {
template <typename... Ts> void sink(Ts...) {}
void dependent_param() {
auto L = [](auto... x) {
return [](decltype(x)... y) { // `y` depends on `x`
return [](int z)
requires requires { sink(y..., z); }
{};
};
};
L(0, 1)(1, 2)(1);
}
} // namespace dependent_param_concept
```
This PR is a prerequisite for implmenting #61426
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/lib/Sema/SemaLambda.cpp
clang/test/SemaTemplate/concepts-lambda.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 795712eac1052..e3ed18e1b288a 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -962,6 +962,7 @@ Bug Fixes to C++ Support
- Fix a crash caused by improper use of ``__array_extent``. (#GH80474)
- Fixed several bugs in capturing variables within unevaluated contexts. (#GH63845), (#GH67260), (#GH69307),
(#GH88081), (#GH89496), (#GH90669) and (#GH91633).
+- Fixed a crash in constraint instantiation under nested lambdas with dependent parameters.
- Fixed handling of brace ellison when building deduction guides. (#GH64625), (#GH83368).
- Clang now instantiates local constexpr functions eagerly for constant evaluators. (#GH35052), (#GH94849)
- Fixed a failed assertion when attempting to convert an integer representing the
diff erence
diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
index 56818042952a6..4b19296e8a23a 100644
--- a/clang/lib/Sema/SemaLambda.cpp
+++ b/clang/lib/Sema/SemaLambda.cpp
@@ -2383,23 +2383,37 @@ Sema::LambdaScopeForCallOperatorInstantiationRAII::
SemaRef.RebuildLambdaScopeInfo(cast<CXXMethodDecl>(FD));
- FunctionDecl *Pattern = getPatternFunctionDecl(FD);
- if (Pattern) {
- SemaRef.addInstantiatedCapturesToScope(FD, Pattern, Scope, MLTAL);
+ FunctionDecl *FDPattern = getPatternFunctionDecl(FD);
+ if (!FDPattern)
+ return;
- FunctionDecl *ParentFD = FD;
- while (ShouldAddDeclsFromParentScope) {
+ SemaRef.addInstantiatedCapturesToScope(FD, FDPattern, Scope, MLTAL);
- ParentFD =
- dyn_cast<FunctionDecl>(getLambdaAwareParentOfDeclContext(ParentFD));
- Pattern =
- dyn_cast<FunctionDecl>(getLambdaAwareParentOfDeclContext(Pattern));
+ if (!ShouldAddDeclsFromParentScope)
+ return;
- if (!ParentFD || !Pattern)
- break;
+ llvm::SmallVector<std::pair<FunctionDecl *, FunctionDecl *>, 4>
+ ParentInstantiations;
+ while (true) {
+ FDPattern =
+ dyn_cast<FunctionDecl>(getLambdaAwareParentOfDeclContext(FDPattern));
+ FD = dyn_cast<FunctionDecl>(getLambdaAwareParentOfDeclContext(FD));
- SemaRef.addInstantiatedParametersToScope(ParentFD, Pattern, Scope, MLTAL);
- SemaRef.addInstantiatedLocalVarsToScope(ParentFD, Pattern, Scope);
- }
+ if (!FDPattern || !FD)
+ break;
+
+ ParentInstantiations.emplace_back(FDPattern, FD);
+ }
+
+ // Add instantiated parameters and local vars to scopes, starting from the
+ // outermost lambda to the innermost lambda. This ordering ensures that
+ // parameters in inner lambdas can correctly depend on those defined
+ // in outer lambdas, e.g. auto L = [](auto... x) {
+ // return [](decltype(x)... y) { }; // `y` depends on `x`
+ // };
+
+ for (const auto &[FDPattern, FD] : llvm::reverse(ParentInstantiations)) {
+ SemaRef.addInstantiatedParametersToScope(FD, FDPattern, Scope, MLTAL);
+ SemaRef.addInstantiatedLocalVarsToScope(FD, FDPattern, Scope);
}
}
diff --git a/clang/test/SemaTemplate/concepts-lambda.cpp b/clang/test/SemaTemplate/concepts-lambda.cpp
index 280be71284f97..252ef08549a48 100644
--- a/clang/test/SemaTemplate/concepts-lambda.cpp
+++ b/clang/test/SemaTemplate/concepts-lambda.cpp
@@ -237,3 +237,17 @@ concept D = []<C T = int>() { return true; }();
D auto x = 0;
} // namespace GH93821
+
+namespace dependent_param_concept {
+template <typename... Ts> void sink(Ts...) {}
+void dependent_param() {
+ auto L = [](auto... x) {
+ return [](decltype(x)... y) {
+ return [](int z)
+ requires requires { sink(y..., z); }
+ {};
+ };
+ };
+ L(0, 1)(1, 2)(1);
+}
+} // namespace dependent_param_concept
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