clang-format: Don't insert spaces in front of :: for Java 8 Method References.

[thakis]

Summary

The existing code kept the space if it was there for identifiers, and it didn't handle this. After this patch, for java this is handled in addition to identifiers, and existing space is always stripped between identifier and ::.

Also accept :: in addition to . in front of < in foo::<T>bar generic calls.

[thakis]

krasimir, do you do clang-format reviews these days? If not, do you know who does?

[krasimir]

I'll take a look. I'm a bit worried that this might potentially affect C++ files too: I'll run an experiment over some random files to confirm that we're not missing something.

[krasimir]

lib/Format/TokenAnnotator.cpp

2558

nit: please add a comment that this example comes from Java.

[krasimir]

Looks good!
I didn't find any instances where this messes-up C++ code (and it looks fine to me for Java code).

[thakis]

Thanks! Will land with tweaked comment.

lib/Format/TokenAnnotator.cpp

2558

Will do. I believe the existing example is Java too.

lib/Format/TokenAnnotator.cpp

bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
   if (Left.is(tok::period) || Right.is(tok::period))
     return false;
   if (Right.is(tok::hash) && Left.is(tok::identifier) && Left.TokenText == "L")
     return false;
   if (Left.is(TT_TemplateCloser) && Left.MatchingParen &&
       Left.MatchingParen->Previous &&
       Left.MatchingParen->Previous->is(tok::period))
     // A.<B<C<...>>>DoSomething();
     return false;
   if (Left.is(TT_TemplateCloser) && Right.is(tok::l_square))
     return false;
   if (Left.is(tok::l_brace) && Left.endsSequence(TT_DictLiteral, tok::at))
     // Objective-C dictionary literal -> no space after opening brace.
     return false;
   if (Right.is(tok::r_brace) && Right.MatchingParen &&
       Right.MatchingParen->endsSequence(TT_DictLiteral, tok::at))
     // Objective-C dictionary literal -> no space before closing brace.
bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
   }
   if (Right.isOneOf(tok::arrow, tok::arrowstar, tok::periodstar) ||
       Left.isOneOf(tok::arrow, tok::period, tok::arrowstar, tok::periodstar) ||
       (Right.is(tok::period) && Right.isNot(TT_DesignatedInitializerPeriod)))
     return false;
   if (!Style.SpaceBeforeAssignmentOperators &&
       Right.getPrecedence() == prec::Assignment)
     return false;
+  if (Style.Language == FormatStyle::LK_Java && Right.is(tok::coloncolon) &&
+      (Left.is(tok::identifier) || Left.is(tok::kw_this)))
+    return false;
   if (Right.is(tok::coloncolon) && Left.is(tok::identifier))
     // Generally don't remove existing spaces between an identifier and "::".
     // The identifier might actually be a macro name such as ALWAYS_INLINE. If
     // this turns out to be too lenient, add analysis of the identifier itself.
     return Right.WhitespaceRange.getBegin() != Right.WhitespaceRange.getEnd();
   if (Right.is(tok::coloncolon) && !Left.isOneOf(tok::l_brace, tok::comment))
     return (Left.is(TT_TemplateOpener) &&
             Style.Standard == FormatStyle::LS_Cpp03) ||

unittests/Format/FormatTestJava.cpp

TEST_F(FormatTestJava, MethodDeclarations) {
   verifyFormat("void methodName(Object arg1,\n"
                "    Object arg2, Object arg3) {}",
                getStyleWithColumns(40));
   verifyFormat("void methodName(\n"
                "    Object arg1, Object arg2) {}",
                getStyleWithColumns(40));
 }
 
+TEST_F(FormatTestJava, MethodReference) {
+  EXPECT_EQ("private void foo() {\n"
+            "  f(this::methodReference);\n"
+            "  f(C.super::methodReference);\n"
+            "  Consumer<String> c = System.out::println;\n"
+            "}",
+            format("private void foo() {\n"
+                   "  f(this ::methodReference);\n"
+                   "  f(C.super ::methodReference);\n"
+                   "  Consumer<String> c = System.out ::println;\n"
+                   "}"));
+}
+
 TEST_F(FormatTestJava, CppKeywords) {
   verifyFormat("public void union(Type a, Type b);");
   verifyFormat("public void struct(Object o);");
   verifyFormat("public void delete(Object o);");
   verifyFormat("return operator && (aa);");
 }
 
 TEST_F(FormatTestJava, NeverAlignAfterReturn) {