clang-format: [JS] Indent namespaces in JavaScript/TS by default.

[mprobst]

Summary

There's no convention of avoiding the nested indentation.

[djasper]

Looks good.

lib/Format/Format.cpp

FormatStyle getGoogleStyle(FormatStyle::LanguageKind Language) {
   } else if (Language == FormatStyle::LK_JavaScript) {
     GoogleStyle.AlignAfterOpenBracket = FormatStyle::BAS_AlwaysBreak;
     GoogleStyle.AlignOperands = false;
     GoogleStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Inline;
     GoogleStyle.AlwaysBreakBeforeMultilineStrings = false;
     GoogleStyle.BreakBeforeTernaryOperators = false;
     GoogleStyle.CommentPragmas = "@(export|return|see|visibility) ";
     GoogleStyle.MaxEmptyLinesToKeep = 3;
+    GoogleStyle.NamespaceIndentation = FormatStyle::NI_All;
     GoogleStyle.SpacesInContainerLiterals = false;
     GoogleStyle.JavaScriptQuotes = FormatStyle::JSQS_Single;
   } else if (Language == FormatStyle::LK_Proto) {
     GoogleStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_None;
     GoogleStyle.SpacesInContainerLiterals = false;
   }
 
   return GoogleStyle;

unittests/Format/FormatTestJS.cpp

verifyFormat("goog.forwardDeclare('this.is.really.absurdly.long');",
                getGoogleJSStyleWithColumns(40));
 
   // These should be wrapped normally.
   verifyFormat(
       "var MyLongClassName =\n"
       "    goog.module.get('my.long.module.name.followedBy.MyLongClassName');");
 }
 
+TEST_F(FormatTestJS, FormatsNamespaces) {
+  verifyFormat("namespace Foo {\n"
+               "  export let x = 1;\n"
+               "}\n");
+  verifyFormat("declare namespace Foo {\n"
+               "  export let x: number;\n"
+               "}\n");
+}
+
 TEST_F(FormatTestJS, FormatsFreestandingFunctions) {
   verifyFormat("function outer1(a, b) {\n"
                "  function inner1(a, b) { return a; }\n"
                "  inner1(a, b);\n"
                "}\n"
                "function outer2(a, b) {\n"
                "  function inner2(a, b) { return a; }\n"
                "  inner2(a, b);\n"