[clang-format] SpaceBeforeParens for lambda expressions

[andrewng]

Ping...

[krasimir]

nit: Please add a sentence on what this patch does in the description.

Thank you!

lib/Format/TokenAnnotator.cpp

return Line.Type == LT_ObjCDecl || Left.is(tok::semi) ||
                           tok::kw_switch, tok::kw_case, TT_ForEachMacro,
                           TT_ObjCForIn) ||
              Left.endsSequence(tok::kw_constexpr, tok::kw_if) ||
              (Left.isOneOf(tok::kw_try, Keywords.kw___except, tok::kw_catch,
                            tok::kw_new, tok::kw_delete) &&
               (!Left.Previous || Left.Previous->isNot(tok::period))))) ||
            (Style.SpaceBeforeParens == FormatStyle::SBPO_Always &&
             (Left.is(tok::identifier) || Left.isFunctionLikeKeyword() ||
-             Left.is(tok::r_paren)) &&
+             Left.is(tok::r_paren) ||
+             (Left.is(tok::r_square) && Left.MatchingParen &&
+              Left.MatchingParen->is(TT_LambdaLSquare))) &&
             Line.Type != LT_PreprocessorDirective);
   }
   if (Left.is(tok::at) && Right.Tok.getObjCKeywordID() != tok::objc_not_keyword)
     return false;
   if (Right.is(TT_UnaryOperator))
     return !Left.isOneOf(tok::l_paren, tok::l_square, tok::at) &&
            (Left.isNot(tok::colon) || Left.isNot(TT_ObjCMethodExpr));
   if ((Left.isOneOf(tok::identifier, tok::greater, tok::r_square,

unittests/Format/FormatTest.cpp

TEST_F(FormatTest, ConfigurableSpaceBeforeParens) {
   verifyFormat("int f(T x) noexcept(x.create());", NoSpace);
   verifyFormat("alignas(128) char a[128];", NoSpace);
   verifyFormat("size_t x = alignof(MyType);", NoSpace);
   verifyFormat("static_assert(sizeof(char) == 1, \"Impossible!\");", NoSpace);
   verifyFormat("int f() throw(Deprecated);", NoSpace);
   verifyFormat("typedef void (*cb)(int);", NoSpace);
   verifyFormat("T A::operator()();", NoSpace);
   verifyFormat("X A::operator++(T);", NoSpace);
+  verifyFormat("auto lambda = []() { return 0; };", NoSpace);
 
   FormatStyle Space = getLLVMStyle();
   Space.SpaceBeforeParens = FormatStyle::SBPO_Always;
 
   verifyFormat("int f ();", Space);
   verifyFormat("void f (int a, T b) {\n"
                "  while (true)\n"
                "    continue;\n"
TEST_F(FormatTest, ConfigurableSpaceBeforeParens) {
   verifyFormat("int f (T x) noexcept (x.create ());", Space);
   verifyFormat("alignas (128) char a[128];", Space);
   verifyFormat("size_t x = alignof (MyType);", Space);
   verifyFormat("static_assert (sizeof (char) == 1, \"Impossible!\");", Space);
   verifyFormat("int f () throw (Deprecated);", Space);
   verifyFormat("typedef void (*cb) (int);", Space);
   verifyFormat("T A::operator() ();", Space);
   verifyFormat("X A::operator++ (T);", Space);
+  verifyFormat("auto lambda = [] () { return 0; };", Space);
 }
 
 TEST_F(FormatTest, ConfigurableSpacesInParentheses) {
   FormatStyle Spaces = getLLVMStyle();
 
   Spaces.SpacesInParentheses = true;
   verifyFormat("do_something( ::globalVar );", Spaces);
   verifyFormat("call( x, y, z );", Spaces);