[Format] Make it easy to add new format::FormatStyle::LanguageStandard. NFCI

[MaskRay]

Summary

Preparatory change for D65043.

We current use !=LS_Cpp03 to enable language standards 11,14,17, and
2a. >=LS_Cpp11 is better if we decide to add new LanguageStandard in
the future.

[modocache]

LGTM, but I don't actively work in this codebase so I really can't say. I'll wait to hear from some other more active clang-format reviewers.

lib/Format/TokenAnnotator.cpp

2862

Just a note: I don't know what the original intent of https://github.com/llvm/llvm-project/commit/dd978ae0e11 was, but in D65043 I modified this condition to be Style.Standard == FormatStyle::LS_Cpp03 || Style.Standard == FormatStyle::LS_Auto, because I believe that mirrors the current behavior exactly. With this change, a user that specified a standard of FormatStyle::LS_Auto will experience a change in behavior.

[sammccall]

I haven't really understood D65043 yet, but I think this is a good change either way.

lib/Format/TokenAnnotator.cpp

2862

If I'm reading the code right, Formatter::analyzecalls deriveLocalStyle first, which replaces LS_Auto with a concrete style. Then later, it calls TokenAnnotator::calculateFormattingInformation which is what ultimately calls spaceRequiredBefore. So I think we never see Auto here, and the two forms are equivalent.

2862

nit: consider < Cpp11, or <= Cpp03? Fits in the spirit of this patch :-)

[MaskRay]

Change to < Cpp11

[MaskRay]

lib/Format/TokenAnnotator.cpp

2862

@modocache LS_Auto will be changed here:

// lib/Format/Formt.cpp:1348
    if (Style.Standard == FormatStyle::LS_Auto)
      Style.Standard = hasCpp03IncompatibleFormat(AnnotatedLines)
                           ? FormatStyle::LS_Cpp11
                           : FormatStyle::LS_Cpp03;

So when you add Cpp2a, be careful here :)

[MaskRay]

Fix another place that should use < FormatStyle::LS_Cpp11 instead`

[sammccall]

lib/Format/Format.cpp

2369–2372

Looking at this more, this is pretty subtle: Style *can* be LS_Auto here. So we're relying on the fact that Auto is the max value in the enum.

It's probably worth making this more explicit, e.g.

LanguageStandard LexingStd = Style.Standard == LS_Auto ? LS_Cpp20 : Style.Standard;
LangOpts.CPlusPlus11 = LexingStd >= FormatStyle::LS_Cpp11;
etc

(a comment would also be fine, but I think the code is at least as clear here)

lib/Format/Format.cpp

tooling::Replacements sortUsingDeclarations(const FormatStyle &Style,
   return UsingDeclarationsSorter(Environment(Code, FileName, Ranges), Style)
       .process()
       .first;
 }
 
 LangOptions getFormattingLangOpts(const FormatStyle &Style) {
   LangOptions LangOpts;
   LangOpts.CPlusPlus = 1;
-  LangOpts.CPlusPlus11 = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
-  LangOpts.CPlusPlus14 = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
-  LangOpts.CPlusPlus17 = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
-  LangOpts.CPlusPlus2a = Style.Standard == FormatStyle::LS_Cpp03 ? 0 : 1;
+  LangOpts.CPlusPlus11 = Style.Standard >= FormatStyle::LS_Cpp11;
+  LangOpts.CPlusPlus14 = Style.Standard >= FormatStyle::LS_Cpp11;
+  LangOpts.CPlusPlus17 = Style.Standard >= FormatStyle::LS_Cpp11;
+  LangOpts.CPlusPlus2a = Style.Standard >= FormatStyle::LS_Cpp11;
   LangOpts.LineComment = 1;
   bool AlternativeOperators = Style.isCpp();
   LangOpts.CXXOperatorNames = AlternativeOperators ? 1 : 0;
   LangOpts.Bool = 1;
   LangOpts.ObjC = 1;
   LangOpts.MicrosoftExt = 1;    // To get kw___try, kw___finally.
   LangOpts.DeclSpecKeyword = 1; // To get __declspec.
   return LangOpts;

lib/Format/TokenAnnotator.cpp

if (Left.is(TT_CastRParen))
     return Style.SpaceAfterCStyleCast ||
            Right.isOneOf(TT_BinaryOperator, TT_SelectorName);
 
   if (Left.is(tok::greater) && Right.is(tok::greater)) {
     if (Style.Language == FormatStyle::LK_TextProto ||
         (Style.Language == FormatStyle::LK_Proto && Left.is(TT_DictLiteral)))
       return !Style.Cpp11BracedListStyle;
     return Right.is(TT_TemplateCloser) && Left.is(TT_TemplateCloser) &&
-           (Style.Standard != FormatStyle::LS_Cpp11 || Style.SpacesInAngles);
+           (Style.Standard < FormatStyle::LS_Cpp11 || Style.SpacesInAngles);
   }
   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) ||
+            Style.Standard < FormatStyle::LS_Cpp11) ||
            !(Left.isOneOf(tok::l_paren, tok::r_paren, tok::l_square,
                           tok::kw___super, TT_TemplateCloser,
                           TT_TemplateOpener)) ||
            (Left.is(tok ::l_paren) && Style.SpacesInParentheses);
   if ((Left.is(TT_TemplateOpener)) != (Right.is(TT_TemplateCloser)))
     return Style.SpacesInAngles;
   // Space before TT_StructuredBindingLSquare.
   if (Right.is(TT_StructuredBindingLSquare))