[llvm-branch-commits] [clang] release/22.x: [Clang] Ensure a lambda DeclContext in BuildLambdaExpr (#176319) (PR #176848)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: None (llvmbot)

<details>
<summary>Changes</summary>

Backport be40637a8

Requested by: @<!-- -->zyn0217

---
Full diff: https://github.com/llvm/llvm-project/pull/176848.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaLambda.cpp (+6-1) 
- (modified) clang/test/SemaCXX/cxx2b-consteval-propagate.cpp (+14) 


``````````diff
diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
index c864a47e022bd..e1b1cd3e04946 100644
--- a/clang/lib/Sema/SemaLambda.cpp
+++ b/clang/lib/Sema/SemaLambda.cpp
@@ -2165,7 +2165,12 @@ ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc,
   // set as CurContext seems more faithful to the source.
   TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
 
-  PopExpressionEvaluationContext();
+  {
+    // TreeTransform of immediate functions may call getCurLambda, which
+    // requires both the paired LSI and the lambda DeclContext.
+    ContextRAII SavedContext(*this, CallOperator, /*NewThisContext=*/false);
+    PopExpressionEvaluationContext();
+  }
 
   sema::AnalysisBasedWarnings::Policy WP =
       AnalysisWarnings.getPolicyInEffectAt(EndLoc);
diff --git a/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp b/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
index 6da589dcf1b25..39097d17441f7 100644
--- a/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
+++ b/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
@@ -629,6 +629,20 @@ void fn() {
 
 }
 
+namespace GH176045 {
+
+template <int NumArgs> struct MessageFormat {
+  template <int N> consteval MessageFormat(const char (&)[N]) {}
+};
+template <typename... Ts> void format(MessageFormat<sizeof...(Ts)>, Ts ...args);
+
+auto message = [] {
+   format("");
+   format("");
+};
+
+}
+
 
 namespace GH109096 {
 consteval void undefined();

``````````

</details>


https://github.com/llvm/llvm-project/pull/176848