[ASTImporter] Support LambdaExprs and improve template support

Also, a number of style and bug fixes was done:

 *  ASTImporterTest: added sanity check for source node
 *  ExternalASTMerger: better lookup for template specializations
 *  ASTImporter: don't add templated declarations into DeclContext
 *  ASTImporter: introduce a helper, ImportTemplateArgumentListInfo getting SourceLocations
 *  ASTImporter: proper set ParmVarDecls for imported FunctionProtoTypeLoc

Differential Revision: https://reviews.llvm.org/D42301

llvm-svn: 323519

2 files changed, 20 insertions, 0 deletions

diff --git a/clang/test/ASTMerge/exprs-cpp/Inputs/exprs3.cpp b/clang/test/ASTMerge/exprs-cpp/Inputs/exprs3.cpp
index 2a33c35d9ea..6fdc33fb391 100644
--- a/clang/test/ASTMerge/exprs-cpp/Inputs/exprs3.cpp
+++ b/clang/test/ASTMerge/exprs-cpp/Inputs/exprs3.cpp
@@ -122,3 +122,20 @@ void useTemplateType() {
 const bool ExpressionTrait = __is_lvalue_expr(1);
 const unsigned ArrayRank = __array_rank(int[10][20]);
 const unsigned ArrayExtent = __array_extent(int[10][20], 1);
+
+constexpr int testLambdaAdd(int toAdd) {
+  const int Captured1 = 1, Captured2 = 2;
+  constexpr auto LambdaAdd = [Captured1, Captured2](int k) -> int {
+    return Captured1 + Captured2 + k;
+  };
+  return LambdaAdd(toAdd);
+}
+
+template<typename T>
+struct TestLambdaTemplate {
+  T i, j;
+  TestLambdaTemplate(T i, const T &j) : i(i), j(j) {}
+  T testLambda(T k) {
+    return [this](T k) -> decltype(auto) { return i + j + k; }(k);
+  }
+};
diff --git a/clang/test/ASTMerge/exprs-cpp/test.cpp b/clang/test/ASTMerge/exprs-cpp/test.cpp
index 0535aa85330..c0b282ec028 100644
--- a/clang/test/ASTMerge/exprs-cpp/test.cpp
+++ b/clang/test/ASTMerge/exprs-cpp/test.cpp
@@ -30,6 +30,8 @@ static_assert(ExpressionTrait == false);
 static_assert(ArrayRank == 2);
 static_assert(ArrayExtent == 20);
 
+static_assert(testLambdaAdd(3) == 6);
+
 void testImport(int *x, const S1 &cs1, S1 &s1) {
   testNewThrowDelete();
   testArrayElement(nullptr, 12);
@@ -44,4 +46,5 @@ void testImport(int *x, const S1 &cs1, S1 &s1) {
   testDefaultArg();
   testDefaultArgExpr();
   useTemplateType();
+  TestLambdaTemplate<int>(1, 2).testLambda(3);
 }