Merge commit '8056d92bc201' from llvm.org/main into next

Author: git apple-llvm automerger

lldb/source/Plugins/ExpressionParser/Clang/ASTUtils.h

@@ -16,6 +16,7 @@
 #include "clang/Sema/Sema.h"
 #include "clang/Sema/SemaConsumer.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
+#include "llvm/Support/Casting.h"
 #include <optional>
 
 namespace clang {
@@ -139,6 +140,24 @@ class ExternalASTSourceWrapper : public ImporterBackedASTSource {
     return m_Source->layoutRecordType(Record, Size, Alignment, FieldOffsets,
                                       BaseOffsets, VirtualBaseOffsets);
   }
+
+  /// This gets called when Sema is reconciling undefined but used decls.
+  /// For LLDB's use-case, we never provide Clang with function definitions,
+  /// instead we rely on linkage names and symbol resolution to call the
+  /// correct funcitons during JITting. So this implementation clears
+  /// any "undefined" FunctionDecls that Clang found while parsing.
+  ///
+  /// \param[in,out] Undefined A set of used decls for which Clang has not
+  ///                          been provided a definition with.
+  ///
+  void ReadUndefinedButUsed(
+      llvm::MapVector<clang::NamedDecl *, clang::SourceLocation> &Undefined)
+      override {
+    Undefined.remove_if([](auto const &decl_loc_pair) {
+      const clang::NamedDecl *ND = decl_loc_pair.first;
+      return llvm::isa_and_present<clang::FunctionDecl>(ND);
+    });
+  }
 };
 
 /// Wraps an ASTConsumer into an SemaConsumer. Doesn't take ownership of the

lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

@@ -1223,6 +1223,8 @@ ClangExpressionParser::ParseInternal(DiagnosticManager &diagnostic_manager,
 
     clang::ExternalASTSource *ast_source = decl_map->CreateProxy();
 
+    auto *ast_source_wrapper = new ExternalASTSourceWrapper(ast_source);
+
     if (ast_context.getExternalSource()) {
       auto *module_wrapper =
           new ExternalASTSourceWrapper(ast_context.getExternalSource());
@@ -1236,6 +1238,7 @@ ClangExpressionParser::ParseInternal(DiagnosticManager &diagnostic_manager,
     } else {
       ast_context.setExternalSource(ast_source);
     }
+    m_compiler->getSema().addExternalSource(ast_source_wrapper);
     decl_map->InstallASTContext(*m_ast_context);
   }
 

lldb/test/Shell/Expr/TestAnonNamespaceParamFunc.cpp

@@ -0,0 +1,22 @@
+// Tests that we can evaluate functions that Clang
+// classifies as having clang::Linkage::UniqueExternal
+// linkage. In this case, a function whose argument
+// is not legally usable outside this TU.
+
+// RUN: %build %s -o %t
+// RUN: %lldb %t -o run -o "expression func(a)" -o exit | FileCheck %s
+
+// CHECK: expression func(a)
+// CHECK: (int) $0 = 15
+
+namespace {
+struct InAnon {};
+} // namespace
+
+int func(InAnon a) { return 15; }
+
+int main() {
+  InAnon a;
+  __builtin_debugtrap();
+  return func(a);
+}