[clang-format] Support breaking consecutive string literals for TableGen

[rupprecht]

Summary

clang-format can get confused by string literals in TableGen: it knows that strings can be broken up, but doesn't seem to understand how that can be indented across line breaks, and arranges them in a weird triangular pattern. Take this output example from clang-format tools/llvm-objcopy/ObjcopyOpts.td (which has now been formatted in rL345896 with this patch applied):

defm keep_global_symbols
: Eq<
      "keep-global-symbols", "Reads a list of symbols from <filename> and "
                             "runs as if " "--keep-global-symbol=<symbol> "
                                           "is set for each one. "
                                           "<filename> " "contains one "
                                                         "symbol per line "
                                                         "and may contain "
                                                         "comments "
                                                         "beginning " "with"
                                                                      " '#'"
                                                                      ". "
                                                                      "Lead"
                                                                      "ing "

[rupprecht]

@djasper -- ping

lib/Format/TokenAnnotator.cpp

if (Right.is(tok::r_brace) && Left.is(tok::l_brace) &&
                   FormatStyle::SFS_InlineOnly);
   } else if (Style.Language == FormatStyle::LK_Java) {
     if (Right.is(tok::plus) && Left.is(tok::string_literal) && Right.Next &&
         Right.Next->is(tok::string_literal))
       return true;
   } else if (Style.Language == FormatStyle::LK_Cpp ||
              Style.Language == FormatStyle::LK_ObjC ||
              Style.Language == FormatStyle::LK_Proto ||
+             Style.Language == FormatStyle::LK_TableGen ||
              Style.Language == FormatStyle::LK_TextProto) {
     if (Left.isStringLiteral() && Right.isStringLiteral())
       return true;
   }
 
   // If the last token before a '}', ']', or ')' is a comma or a trailing
   // comment, the intention is to insert a line break after it in order to make
   // shuffling around entries easier. Import statements, especially in

unittests/Format/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   Support
   )
 
 add_clang_unittest(FormatTests
   CleanupTest.cpp
   FormatTest.cpp
   FormatTestComments.cpp
   FormatTestJS.cpp
   FormatTestJava.cpp
   FormatTestObjC.cpp
   FormatTestProto.cpp
   FormatTestRawStrings.cpp
   FormatTestSelective.cpp
+  FormatTestTableGen.cpp
   FormatTestTextProto.cpp
   NamespaceEndCommentsFixerTest.cpp
   SortImportsTestJS.cpp
   SortImportsTestJava.cpp
   SortIncludesTest.cpp
   UsingDeclarationsSorterTest.cpp
   )
 
 target_link_libraries(FormatTests
   PRIVATE
   clangBasic
   clangFormat
   clangFrontend
   clangRewrite
   clangToolingCore
   )

unittests/Format/FormatTestTableGen.cpp

+//===- unittest/Format/FormatTestTableGen.cpp -----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "FormatTestUtils.h"
+#include "clang/Format/Format.h"
+#include "llvm/Support/Debug.h"
+#include "gtest/gtest.h"
+
+#define DEBUG_TYPE "format-test"
+
+namespace clang {
+namespace format {
+
+class FormatTestTableGen : public ::testing::Test {
+protected:
+  static std::string format(llvm::StringRef Code, unsigned Offset,
+                            unsigned Length, const FormatStyle &Style) {
+    LLVM_DEBUG(llvm::errs() << "---\n");
+    LLVM_DEBUG(llvm::errs() << Code << "\n\n");
+    std::vector<tooling::Range> Ranges(1, tooling::Range(Offset, Length));
+    tooling::Replacements Replaces = reformat(Style, Code, Ranges);
+    auto Result = applyAllReplacements(Code, Replaces);
+    EXPECT_TRUE(static_cast<bool>(Result));
+    LLVM_DEBUG(llvm::errs() << "\n" << *Result << "\n\n");
+    return *Result;
+  }
+
+  static std::string format(llvm::StringRef Code) {
+    FormatStyle Style = getGoogleStyle(FormatStyle::LK_TableGen);
+    Style.ColumnLimit = 60; // To make writing tests easier.
+    return format(Code, 0, Code.size(), Style);
+  }
+
+  static void verifyFormat(llvm::StringRef Code) {
+    EXPECT_EQ(Code.str(), format(Code)) << "Expected code is not stable";
+    EXPECT_EQ(Code.str(), format(test::messUp(Code)));
+  }
+};
+
+TEST_F(FormatTestTableGen, FormatStringBreak) {
+  verifyFormat("include \"OptParser.td\"\n"
+               "def flag : Flag<\"--foo\">,\n"
+               "           HelpText<\n"
+               "               \"This is a very, very, very, very, \"\n"
+               "               \"very, very, very, very, very, very, \"\n"
+               "               \"very long help string\">;\n");
+}
+
+} // namespace format
+} // end namespace clang