clang-format: Correctly mark preprocessor lines in child blocks.

This prevents contracting:
  auto lambda = []() {
    int a = 2
  #if A
            + 2
  #endif
        ;
  };

into:
  auto lambda = []() { int a = 2
  #if A + 2
  #endif ; };

Which is obviously BAD.

This fixes llvm.org/PR22496.

llvm-svn: 228522

clang/lib/Format/UnwrappedLineParser.cpp

@@ -1677,8 +1677,7 @@ void UnwrappedLineParser::readToken() {
            (FormatTok->HasUnescapedNewline || FormatTok->IsFirst)) {
       // If there is an unfinished unwrapped line, we flush the preprocessor
       // directives only after that unwrapped line was finished later.
-      bool SwitchToPreprocessorLines =
-          !Line->Tokens.empty() && CurrentLines == &Lines;
+      bool SwitchToPreprocessorLines = !Line->Tokens.empty();
       ScopedLineState BlockState(*this, SwitchToPreprocessorLines);
       // Comments stored before the preprocessor directive need to be output
       // before the preprocessor directive, at the same level as the

clang/unittests/Format/FormatTest.cpp

@@ -9529,6 +9529,13 @@ TEST_F(FormatTest, FormatsLambdas) {
                "      doo_dah();\n"
                "    })) {\n"
                "}");
+  verifyFormat("auto lambda = []() {\n"
+               "  int a = 2\n"
+               "#if A\n"
+               "          + 2\n"
+               "#endif\n"
+               "      ;\n"
+               "};");
 }
 
 TEST_F(FormatTest, FormatsBlocks) {