[PATCH] D79401: [clang-format] [PR45639] clang-format splits up the brackets of C++17 attribute [[ ]] when used with the first parameter

Wed May 6 12:26:09 PDT 2020

krasimir added a comment.

I think we should never break apart the two `[[` and `]]` of attributes.
Running that example with `-debug` shows that we consider breaking between the two `[` tokens a valid possibility.

- `C=1` means breaking before the token is OK, which is probably computed by `TokenAnnotator::canBreakBefore`:

  % bin/clang-format -debug ~/test.cc
  Line(0, FSC=0): void[T=85, OC=0] identifier[T=85, OC=5] coloncolon[T=85, OC=22] identifier[T=85, OC=24] l_paren[T=85, OC=50] l_square[T=85, OC=51] l_square[T=85, OC=52] identifier[T=85, OC=53] r_square[T=85, OC=65] r_square[T=85, OC=66] const[T=85, OC=68] identifier[T=85, OC=74] less[T=85, OC=84] identifier[T=85, OC=85] greater[T=85, OC=98] amp[T=85, OC=99] identifier[T=85, OC=101] identifier[T=85, OC=51] r_paren[T=85, OC=59] l_brace[T=21, OC=61] 
  Line(0, FSC=0): r_brace[T=85, OC=0] 
  Line(0, FSC=0): eof[T=85, OC=0] 
  Run 0...
  AnnotatedTokens(L=0):
   M=0 C=0 T=Unknown S=1 B=0 BK=0 P=0 Name=void L=4 PPK=2 FakeLParens= FakeRParens=0 II=0x219c910 Text='void'
   M=0 C=1 T=FunctionDeclarationName S=1 B=0 BK=0 P=80 Name=identifier L=22 PPK=2 FakeLParens= FakeRParens=0 II=0x21d8210 Text='SomeLongClassName'
   M=0 C=0 T=Unknown S=0 B=0 BK=0 P=23 Name=coloncolon L=24 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text='::'
   M=0 C=1 T=Unknown S=0 B=0 BK=0 P=520 Name=identifier L=50 PPK=2 FakeLParens= FakeRParens=0 II=0x21d8258 Text='ALongMethodNameInThatClass'
   M=0 C=0 T=Unknown S=0 B=0 BK=0 P=23 Name=l_paren L=51 PPK=1 FakeLParens= FakeRParens=0 II=0x0 Text='('
   M=0 C=1 T=AttributeSquare S=0 B=0 BK=0 P=140 Name=l_square L=52 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text='['
   M=0 C=1 T=AttributeSquare S=0 B=0 BK=0 P=79 Name=l_square L=53 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text='['
   M=0 C=0 T=Unknown S=0 B=0 BK=0 P=99 Name=identifier L=65 PPK=2 FakeLParens= FakeRParens=0 II=0x21d8290 Text='maybe_unused'
   M=0 C=0 T=AttributeSquare S=0 B=0 BK=0 P=83 Name=r_square L=66 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text=']'
   M=0 C=0 T=AttributeSquare S=0 B=0 BK=0 P=63 Name=r_square L=67 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text=']'
   M=0 C=0 T=Unknown S=1 B=0 BK=0 P=43 Name=const L=73 PPK=2 FakeLParens= FakeRParens=0 II=0x219c3e8 Text='const'
   M=0 C=0 T=Unknown S=1 B=0 BK=0 P=43 Name=identifier L=84 PPK=2 FakeLParens= FakeRParens=0 II=0x21d82c8 Text='shared_ptr'
   M=0 C=0 T=TemplateOpener S=0 B=0 BK=0 P=50 Name=less L=85 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text='<'
   M=0 C=1 T=Unknown S=0 B=0 BK=0 P=380 Name=identifier L=98 PPK=2 FakeLParens= FakeRParens=0 II=0x21d8300 Text='ALongTypeName'
   M=0 C=0 T=TemplateCloser S=0 B=0 BK=0 P=290 Name=greater L=99 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text='>'
   M=0 C=1 T=PointerOrReference S=1 B=0 BK=0 P=230 Name=amp L=101 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text='&'
   M=0 C=1 T=StartOfName S=0 B=0 BK=0 P=240 Name=identifier L=120 PPK=2 FakeLParens= FakeRParens=0 II=0x21d8340 Text='argumentNameForThat'
   M=0 C=1 T=StartOfName S=1 B=0 BK=0 P=150 Name=identifier L=129 PPK=2 FakeLParens= FakeRParens=0 II=0x21d8378 Text='LongType'
   M=0 C=0 T=Unknown S=0 B=0 BK=0 P=43 Name=r_paren L=130 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text=')'
   M=0 C=0 T=FunctionLBrace S=1 B=0 BK=1 P=23 Name=l_brace L=132 PPK=2 FakeLParens= FakeRParens=0 II=0x0 Text='{'
  ----

You could adapt that code to not break before the second `TT_AttributeSquare` in `[[` or `]]`; this will have the same effect and generalize.

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D79401/new/

https://reviews.llvm.org/D79401