[clang-format] Fix bug where -dump-config failed on ObjC header

[benhamilton]

Summary

clang-format -dump-config path/to/file.h never passed
anything for the Code parameter to clang::format::getStyle().

This meant the logic to guess Objective-C from the contents
of a .h file never worked, because LibFormat didn't have the
code to work with.

With this fix, we now correctly read in the contents of the
file if possible with -dump-config.

I had to update the lit config for test/Format/ because
the default config ignores .h files.

Test Plan: make -j12 check-clang

[benhamilton]

• Support AssumeFileName with stdin.

[jolesiak]

test/Format/lit.local.cfg

2–3

Where does this list come from?
Shouldn't '.textpb', 'METADATA', '.c', '.cc' be added here?

[benhamilton]

• Add more extensions.

[benhamilton]

test/Format/lit.local.cfg

2–3

It's a good question, thanks.

I copied this list from LibFormat's getLanguageByFileName():

https://github.com/llvm-mirror/clang/blob/master/lib/Format/Format.cpp#L2265

I did miss .textpb, added now. I also added .c and .cc since they should default to C++ style.

METADATA isn't a suffix understood by clang-format, so I did not add it.

[krasimir]

test/Format/lit.local.cfg

2

Why is this needed?

[benhamilton]

test/Format/lit.local.cfg

2

'.h' is not in the list of file suffixes which lit is configured to look for:

https://github.com/llvm-mirror/clang/blob/master/test/lit.cfg.py#L28

So, we need to provide our own list of file suffixes here.

Other tests do the same:

https://github.com/llvm-mirror/clang/search?utf8=%E2%9C%93&q=%22config.suffixes%22&type=

so I think it's OK to do so here as well.

[krasimir]

test/Format/lit.local.cfg

2

Thank you!

test/Format/dump-config-cxx.h

+// RUN: clang-format -dump-config %s | FileCheck %s
+
+// CHECK: Language: Cpp

test/Format/dump-config-objc.h

+// RUN: clang-format -dump-config %s | FileCheck %s
+
+// CHECK: Language: ObjC
+@interface Foo
+@end

test/Format/lit.local.cfg

+# Suffixes supported by clang-format.
+config.suffixes = ['.cpp', '.h', '.m', '.mm', '.java', '.js', '.ts', '.proto',
+                   '.protodevel', '.pb.txt', '.textproto', '.asciipb', '.td']

tools/clang-format/ClangFormat.cpp

cl::ParseCommandLineOptions(
       "result is written to the standard output.\n");
 
   if (Help) {
     cl::PrintHelpMessage();
     return 0;
   }
 
   if (DumpConfig) {
+    StringRef FileName;
+    std::unique_ptr<llvm::MemoryBuffer> Code;
+    if (FileNames.empty()) {
+      // We can't read the code to detect the language if there's no
+      // file name, so leave Code empty here.
+      FileName = AssumeFileName;
+    } else {
+      // Read in the code in case the filename alone isn't enough to
+      // detect the language.
+      ErrorOr<std::unique_ptr<MemoryBuffer>> CodeOrErr =
+          MemoryBuffer::getFileOrSTDIN(FileNames[0]);
+      if (std::error_code EC = CodeOrErr.getError()) {
+        llvm::errs() << EC.message() << "\n";
+        return 1;
+      }
+      FileName = (FileNames[0] == "-") ? AssumeFileName : FileNames[0];
+      Code = std::move(CodeOrErr.get());
+    }
     llvm::Expected<clang::format::FormatStyle> FormatStyle =
-        clang::format::getStyle(
-            Style, FileNames.empty() ? AssumeFileName : FileNames[0],
-            FallbackStyle);
+        clang::format::getStyle(Style, FileName, FallbackStyle,
+                                Code ? Code->getBuffer() : "");
     if (!FormatStyle) {
       llvm::errs() << llvm::toString(FormatStyle.takeError()) << "\n";
       return 1;
     }
     std::string Config = clang::format::configurationAsText(*FormatStyle);
     outs() << Config << "\n";
     return 0;
   }