[Lldb-commits] [lldb] [lldb][ClangASTImporter] Don't ASTImport LambdaExpr nodes (PR #154962)

[via lldb-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: Michael Buch (Michael137)

<details>
<summary>Changes</summary>

Works around https://github.com/llvm/llvm-project/issues/149477

---
Full diff: https://github.com/llvm/llvm-project/pull/154962.diff


2 Files Affected:

- (modified) lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp (+10) 
- (added) lldb/test/Shell/Expr/TestLambdaExprImport.test (+26) 


``````````diff
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp
index 08e2d0f1b4011..92094c01e2a54 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp
@@ -1048,6 +1048,16 @@ ClangASTImporter::MapCompleter::~MapCompleter() = default;
 
 llvm::Expected<Decl *>
 ClangASTImporter::ASTImporterDelegate::ImportImpl(Decl *From) {
+  // FIXME: The Minimal import mode of clang::ASTImporter does not correctly
+  // import Lambda definitions. Work around this for now by not importing
+  // lambdas at all. This is most likely encountered when importing decls from
+  // the `std` module (not from debug-info), where lambdas can be defined in
+  // inline function bodies. Those will be imported by LLDB.
+  if (const auto *CXX = llvm::dyn_cast<clang::CXXRecordDecl>(From))
+    if (CXX->isLambda())
+      return llvm::make_error<ASTImportError>(
+          ASTImportError::UnsupportedConstruct);
+
   if (m_std_handler) {
     std::optional<Decl *> D = m_std_handler->Import(From);
     if (D) {
diff --git a/lldb/test/Shell/Expr/TestLambdaExprImport.test b/lldb/test/Shell/Expr/TestLambdaExprImport.test
new file mode 100644
index 0000000000000..c57ce06453fe2
--- /dev/null
+++ b/lldb/test/Shell/Expr/TestLambdaExprImport.test
@@ -0,0 +1,26 @@
+# Test that we can successfully ASTImport clang::LambdaExpr nodes.
+# Currently this is not supported in MinimalImport mode (which LLDB
+# uses always).
+
+# RUN: split-file %s %t
+# RUN: %clang_host -g -gdwarf %t/main.cpp -o %t.out
+# RUN: %lldb -o "settings set interpreter.stop-command-source-on-error false" \
+# RUN:       -x -b -s %t/commands.input %t.out 2>&1 \
+# RUN:       | FileCheck %s
+
+#--- main.cpp
+
+int main() {
+  __builtin_debugtrap();
+}
+
+#--- commands.input
+
+run
+expression --top-level -- void method(int x) { [x=x] { ; }; }
+target dump typesystem
+
+# CHECK:      expression
+# CHECK:      target dump typesystem
+# CHECK-NOT:  FunctionDecl
+# CHECK-NOT:  LambdaExpr

``````````

</details>


https://github.com/llvm/llvm-project/pull/154962