[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, 18 insertions, 0 deletions

diff --git a/clang/test/ASTMerge/function-cpp/Inputs/function-1.cpp b/clang/test/ASTMerge/function-cpp/Inputs/function-1.cpp
new file mode 100644
index 00000000000..ee97a1a8a5d
--- /dev/null
+++ b/clang/test/ASTMerge/function-cpp/Inputs/function-1.cpp
@@ -0,0 +1,8 @@
+
+template<typename T> constexpr T add(T arg1, T arg2) {
+  return arg1 + arg2;
+}
+
+template<> constexpr int add(int arg1, int arg2) {
+  return arg1 + arg2 + 2;
+}
diff --git a/clang/test/ASTMerge/function-cpp/test.cpp b/clang/test/ASTMerge/function-cpp/test.cpp
new file mode 100644
index 00000000000..304ce3c634c
--- /dev/null
+++ b/clang/test/ASTMerge/function-cpp/test.cpp
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -std=c++1z -emit-pch -o %t.1.ast %S/Inputs/function-1.cpp
+// RUN: %clang_cc1 -std=c++1z  -ast-merge %t.1.ast -fsyntax-only %s 2>&1 | FileCheck %s
+// XFAIL: *
+
+static_assert(add(1, 2) == 5);
+
+// FIXME: support of templated function overload is still not implemented.
+static_assert(add('\1', '\2') == 3);
+
+// CHECK-NOT: static_assert