[clang-format] Fixup a case of text proto message attributes

[krasimir]

Summary

This patch fixes a case where a proto message attribute is wrongly identified as an text proto extension.

lib/Format/TokenAnnotator.cpp

if (Left->isCppStructuredBinding(Style)) {
       } else if (Style.Language == FormatStyle::LK_Proto ||
                  Style.Language == FormatStyle::LK_TextProto) {
         // Square braces in LK_Proto can either be message field attributes:
         //
         // optional Aaa aaa = 1 [
         //   (aaa) = aaa
         // ];
         //
+        // extensions 123 [
+        //   (aaa) = aaa
+        // ];
+        //
         // or text proto extensions (in options):
         //
         // option (Aaa.options) = {
         //   [type.type/type] {
         //     key: value
         //   }
         // }
         //
         // or repeated fields (in options):
         //
         // option (Aaa.options) = {
         //   keys: [ 1, 2, 3 ]
         // }
         //
         // In the first and the third case we want to spread the contents inside
         // the square braces; in the second we want to keep them inline.
         Left->Type = TT_ArrayInitializerLSquare;
         if (!Left->endsSequence(tok::l_square, tok::numeric_constant,
                                 tok::equal) &&
+            !Left->endsSequence(tok::l_square, tok::numeric_constant,
+                                tok::identifier) &&
             !Left->endsSequence(tok::l_square, tok::colon, TT_SelectorName)) {
           Left->Type = TT_ProtoExtensionLSquare;
           BindingIncrease = 10;
         }
       } else if (!CppArrayTemplates && Parent &&
                  Parent->isOneOf(TT_BinaryOperator, TT_TemplateCloser, tok::at,
                                  tok::comma, tok::l_paren, tok::l_square,
                                  tok::question, tok::colon, tok::kw_return,

unittests/Format/FormatTestProto.cpp

verifyFormat("optional string test = 1 [default =\n"
                "                              \"test\"];");
   verifyFormat("optional Aaaaaaaa aaaaaaaa = 12 [\n"
                "  (aaa) = aaaa,\n"
                "  (bbbbbbbbbbbbbbbbbbbbbbbbbb) = {\n"
                "    aaaaaaaaaaaaaaaaa: true,\n"
                "    aaaaaaaaaaaaaaaa: true\n"
                "  }\n"
                "];");
+  verifyFormat("extensions 20 [(proto2.type) = 'Aaaa.bbbb'];");
+  verifyFormat("extensions 20\n"
+               "    [(proto3.type) = 'Aaaa.bbbb', (aaa.Aaa) = 'aaa.bbb'];");
+  verifyFormat("extensions 123 [\n"
+               "  (aaa) = aaaa,\n"
+               "  (bbbbbbbbbbbbbbbbbbbbbbbbbb) = {\n"
+               "    aaaaaaaaaaaaaaaaa: true,\n"
+               "    aaaaaaaaaaaaaaaa: true\n"
+               "  }\n"
+               "];");
 }
 
 TEST_F(FormatTestProto, DoesntWrapFileOptions) {
   EXPECT_EQ(
       "option java_package = "
       "\"some.really.long.package.that.exceeds.the.column.limit\";",
       format("option    java_package   =    "
              "\"some.really.long.package.that.exceeds.the.column.limit\";"));