[ASTImporter] Fix import of lambda in function param

Summary:
The current import implementation fails to import the definition of a
lambda class if the lambda class is defined in a function param.
E.g., the lambda class below will be imported without any methods:
```
  template <typename F>
  void f(F L = [](){}) {}
```

Reviewers: a_sidorin, a.sidorin, shafik

Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64073

llvm-svn: 365315

1 files changed, 39 insertions, 0 deletions

diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
index 165946a669f..6b8315f2b9e 100644
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -5083,6 +5083,45 @@ INSTANTIATE_TEST_CASE_P(ParameterizedTests, DeclContextTest,
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, CanonicalRedeclChain,
                         ::testing::Values(ArgVector()), );
 
+TEST_P(ASTImporterOptionSpecificTestBase, LambdaInFunctionBody) {
+  Decl *FromTU = getTuDecl(
+      R"(
+      void f() {
+        auto L = [](){};
+      }
+      )",
+      Lang_CXX11, "input0.cc");
+  auto Pattern = lambdaExpr();
+  CXXRecordDecl *FromL =
+      FirstDeclMatcher<LambdaExpr>().match(FromTU, Pattern)->getLambdaClass();
+
+  auto ToL = Import(FromL, Lang_CXX11);
+  unsigned ToLSize = std::distance(ToL->decls().begin(), ToL->decls().end());
+  unsigned FromLSize =
+      std::distance(FromL->decls().begin(), FromL->decls().end());
+  EXPECT_NE(ToLSize, 0u);
+  EXPECT_EQ(ToLSize, FromLSize);
+}
+
+TEST_P(ASTImporterOptionSpecificTestBase, LambdaInFunctionParam) {
+  Decl *FromTU = getTuDecl(
+      R"(
+      template <typename F>
+      void f(F L = [](){}) {}
+      )",
+      Lang_CXX11, "input0.cc");
+  auto Pattern = lambdaExpr();
+  CXXRecordDecl *FromL =
+      FirstDeclMatcher<LambdaExpr>().match(FromTU, Pattern)->getLambdaClass();
+
+  auto ToL = Import(FromL, Lang_CXX11);
+  unsigned ToLSize = std::distance(ToL->decls().begin(), ToL->decls().end());
+  unsigned FromLSize =
+      std::distance(FromL->decls().begin(), FromL->decls().end());
+  EXPECT_NE(ToLSize, 0u);
+  EXPECT_EQ(ToLSize, FromLSize);
+}
+
 INSTANTIATE_TEST_CASE_P(ParameterizedTests, ASTImporterLookupTableTest,
                         DefaultTestValuesForRunOptions, );