[clang-format] Missing space between trailing return type 'auto' and left brace

[denis-fatkulin]

Summary

There's no a space symbol between trailing return type auto and left brace {.

The simpliest examles of code to reproduce the issue:

[]() -> auto {}

and

auto foo() -> auto {}

Depends on D130299

[HazardyKnusperkeks]

Thanks!

[owenpan]

clang/unittests/Format/FormatTest.cpp

23555–23556

Should we add test cases with an & between auto and {?

[curdeius]

clang/unittests/Format/FormatTest.cpp

23555–23556

👍

[denis-fatkulin]

Test cases for auto & and auto * are added

[HazardyKnusperkeks]

You should mark comments as done, if so.

[denis-fatkulin]

They marked done. Thanks!

clang/unittests/Format/FormatTest.cpp

23555–23556

Then it's better to add the case not only for auto &, but for auto * too.
But actually these cases are hadled correctly without this patch.

[denis-fatkulin]

Conflict with 'main' branch was solved

clang/lib/Format/TokenAnnotator.cpp

if (Style.SpacesInConditionalStatement) {
     else if (Right.is(tok::r_paren) && Right.MatchingParen)
       LeftParen = Right.MatchingParen;
     if (LeftParen && LeftParen->Previous &&
         isKeywordWithCondition(*LeftParen->Previous)) {
       return true;
     }
   }
 
+  // trailing return type 'auto': []() -> auto {}, auto foo() -> auto {}
+  if (Left.is(tok::kw_auto) &&
+      Right.isOneOf(TT_LambdaLBrace, TT_FunctionLBrace))
+    return true;
+
   // auto{x} auto(x)
   if (Left.is(tok::kw_auto) && Right.isOneOf(tok::l_paren, tok::l_brace))
     return false;
 
   // operator co_await(x)
   if (Right.is(tok::l_paren) && Left.is(tok::kw_co_await) && Left.Previous &&
       Left.Previous->is(tok::kw_operator)) {
     return false;

clang/unittests/Format/FormatTest.cpp

TEST_F(FormatTest, AmbersandInLamda) {
   // Test case reported in https://bugs.llvm.org/show_bug.cgi?id=41899
   FormatStyle AlignStyle = getLLVMStyle();
   AlignStyle.PointerAlignment = FormatStyle::PAS_Left;
   verifyFormat("auto lambda = [&a = a]() { a = 2; };", AlignStyle);
   AlignStyle.PointerAlignment = FormatStyle::PAS_Right;
   verifyFormat("auto lambda = [&a = a]() { a = 2; };", AlignStyle);
 }
 
+TEST_F(FormatTest, TrailingReturnTypeAuto) {
+  FormatStyle Style = getLLVMStyle();
+  verifyFormat("[]() -> auto { return Val; }", Style);
+  verifyFormat("auto foo() -> auto { return Val; }", Style);
+}
+
 TEST_F(FormatTest, SpacesInConditionalStatement) {
   FormatStyle Spaces = getLLVMStyle();
   Spaces.IfMacros.clear();
   Spaces.IfMacros.push_back("MYIF");
   Spaces.SpacesInConditionalStatement = true;
   verifyFormat("for ( int i = 0; i; i++ )\n  continue;", Spaces);
   verifyFormat("if ( !a )\n  return;", Spaces);
   verifyFormat("if ( a )\n  return;", Spaces);