[v5] Add .clang-format style file

  Went with version >= 11.0 since it covers most of the major features
and should be pretty universally accessibly.

There are some issues:

1.  indention of preprocessor directives:
    Unfortunately there doesn't appear to be a switch for a seperate
    'IndentWidth' for preprocessor directives vs. normal code so we
    are stuck either not indenting the directives or over-indenting
    them. i.e:
    Desired:
    ```
    #ifndef A
    # define B
    #endif
    ```
    Options:
    ```
    #ifndef A
    #  define B /* Two spaces instead of one.  */
    #endif

    #ifndef C
    #define D   /* No spaces.  */
    #endif
    ```
    Chose to over-indent as it generally seems easier to script
    halving all pre-processor indentations than counting the nested
    depth and indenting from scratch.

2.  concatenation of lines missing semi-colons:
    Throughout glibc there are macros used to setup aliasing that are
    outside of functions and don't end in semi-colons i.e:
    ```
    libc_hidden_def (__pthread_self)
    weak_alias (__pthread_self, pthread_self)
    ```

    clang-format reformats lines like these to:
    ```
    libc_hidden_def (__pthread_self) weak_alias (__pthread_self, pthread_self)
    ```

    which is generally undesirable.

Other than those two big concerns there are certainly some questions
diffs but for the most part it creates a easy to read and consistent
style.
---
 .clang-format | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 .clang-format
  

On 3/30/22 16:24, Noah Goldstein via Libc-alpha wrote:
> Went with version >= 11.0 since it covers most of the major features
> and should be pretty universally accessibly.

Almost there. I think with v6 we'll have a version we can commit.

Thanks for iterating.
 
> There are some issues:
> 
> 1.  indention of preprocessor directives:
>     Unfortunately there doesn't appear to be a switch for a seperate
>     'IndentWidth' for preprocessor directives vs. normal code so we
>     are stuck either not indenting the directives or over-indenting
>     them. i.e:
>     Desired:
>     ```
>     #ifndef A
>     # define B
>     #endif
>     ```
>     Options:
>     ```
>     #ifndef A
>     #  define B /* Two spaces instead of one.  */
>     #endif
> 
>     #ifndef C
>     #define D   /* No spaces.  */
>     #endif
>     ```
>     Chose to over-indent as it generally seems easier to script
>     halving all pre-processor indentations than counting the nested
>     depth and indenting from scratch.
> 
> 2.  concatenation of lines missing semi-colons:
>     Throughout glibc there are macros used to setup aliasing that are
>     outside of functions and don't end in semi-colons i.e:
>     ```
>     libc_hidden_def (__pthread_self)
>     weak_alias (__pthread_self, pthread_self)
>     ```
> 
>     clang-format reformats lines like these to:
>     ```
>     libc_hidden_def (__pthread_self) weak_alias (__pthread_self, pthread_self)
>     ```
> 
>     which is generally undesirable.
> 
> Other than those two big concerns there are certainly some questions
> diffs but for the most part it creates a easy to read and consistent
> style.
> ---
>  .clang-format | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 156 insertions(+)
>  create mode 100644 .clang-format
> 
> diff --git a/.clang-format b/.clang-format
> new file mode 100644
> index 0000000000..c0d993fd03
> --- /dev/null
> +++ b/.clang-format
> @@ -0,0 +1,156 @@
> +#  clang-format file for GLIBC
> +#  Copyright (C) 2022 Free Software Foundation, Inc.
> +#  This file is part of the GNU C Library.
> +#
> +#  The GNU C Library is free software; you can redistribute it and/or
> +#  modify it under the terms of the GNU Lesser General Public
> +#  License as published by the Free Software Foundation; either
> +#  version 2.1 of the License, or (at your option) any later version.
> +#
> +#  The GNU C Library is distributed in the hope that it will be useful,
> +#  but WITHOUT ANY WARRANTY; without even the implied warranty of
> +#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +#  Lesser General Public License for more details.
> +#
> +#  You should have received a copy of the GNU Lesser General Public
> +#  License along with the GNU C Library; if not, see
> +#  <https://www.gnu.org/licenses/>.
> +#
> +#  Requires clang-format version >= 11.0
> +#
> +#  For more information, see:
> +#
> +#   Documentation/process/clang-format.rst

This is not a valid path in the glibc source tree.

> +#   https://clang.llvm.org/docs/ClangFormat.html
> +#   https://clang.llvm.org/docs/ClangFormatStyleOptions.html
> +#
> +#  There are some known cases that this doesn't produce the desired
> +#  style (i.e Preprocessor Directives are over-indented and not
> +#  auto-commented). As a result, this is meant to be a utility to make
> +#  formatting easier, not a definitive standard.
> +#
> +#  To format the current git diff inplace (-i) the follow command can
> +#  be used:
> +#  $> git diff -U0 --no-color HEAD^ | clang-format-diff -i -p1
> +#
> +#  To just view the diff clang-format would generate:
> +#  $> git diff -U0 --no-color HEAD^ | clang-format-diff -p1
> +#
> +#  NB: clang-format-diff, along with other clang-format related tools,
> +#      can be found at: /path/to/llvm-project/clang/tools/clang-format/
> +#
> +#
> +---
> +# BasedOnStyle:  GNU

Suggest:

# This file is based on the existing GNU style e.g. BasedOnStyle:  GNU.

Otherwise developers will be confused why the directive is commented out.

> +AccessModifierOffset: -2
> +AlignAfterOpenBracket: Align
> +AlignConsecutiveMacros: false
> +AlignConsecutiveAssignments: false
> +AlignConsecutiveBitFields: false
> +AlignConsecutiveDeclarations: false
> +AlignEscapedNewlines: Right
> +AlignOperands:   true
> +AlignTrailingComments: true
> +AllowAllArgumentsOnNextLine: true
> +AllowAllParametersOfDeclarationOnNextLine: true
> +AllowShortEnumsOnASingleLine: true
> +AllowShortBlocksOnASingleLine: false
> +AllowShortCaseLabelsOnASingleLine: false
> +AllowShortFunctionsOnASingleLine: All
> +AllowShortLambdasOnASingleLine: All
> +AllowShortIfStatementsOnASingleLine: Never
> +AllowShortLoopsOnASingleLine: false
> +AlwaysBreakAfterDefinitionReturnType: All
> +AlwaysBreakAfterReturnType: AllDefinitions
> +AlwaysBreakBeforeMultilineStrings: false
> +BinPackArguments: true
> +BinPackParameters: true
> +BraceWrapping:
> +  AfterCaseLabel:  true
> +  AfterClass:      true
> +  AfterControlStatement: true
> +  AfterEnum:       true
> +  AfterFunction:   true
> +  AfterNamespace:  true
> +  AfterStruct:     true
> +  AfterUnion:      true
> +  AfterExternBlock: true
> +  BeforeCatch:     true
> +  BeforeElse:      true
> +  BeforeWhile:     true
> +  IndentBraces:    true
> +  SplitEmptyFunction: true
> +  SplitEmptyRecord: true
> +  SplitEmptyNamespace: true
> +BreakBeforeBinaryOperators: All
> +BreakBeforeBraces: GNU
> +BreakBeforeInheritanceComma: false
> +BreakInheritanceList: BeforeColon
> +BreakBeforeTernaryOperators: true
> +BreakStringLiterals: true
> +ColumnLimit:     79
> +CommentPragmas:  '^ IWYU pragma:'
> +CompactNamespaces: false
> +ContinuationIndentWidth: 4
> +Cpp11BracedListStyle: false
> +DeriveLineEnding: true
> +DerivePointerAlignment: false
> +DisableFormat:   false
> +ExperimentalAutoDetectBinPacking: false
> +FixNamespaceComments: false
> +IncludeBlocks:   Preserve
> +IncludeCategories:
> +  - Regex:           '.*'
> +    Priority:        1

OK. Resolves Florian's comment regarding IncludeCategories.

> +IncludeIsMainRegex: '(Test)?$'
> +IndentCaseLabels: false
> +IndentCaseBlocks: false
> +IndentGotoLabels: true
> +IndentWidth:     2
> +IndentPPDirectives: AfterHash
> +IndentExternBlock: AfterExternBlock
> +IndentWrappedFunctionNames: false
> +InsertTrailingCommas: None
> +KeepEmptyLinesAtTheStartOfBlocks: true
> +MacroBlockBegin: ''
> +MacroBlockEnd:   ''
> +MaxEmptyLinesToKeep: 1
> +NamespaceIndentation: None
> +PenaltyBreakAssignment: 2
> +PenaltyBreakBeforeFirstCallParameter: 19
> +PenaltyBreakComment: 300
> +PenaltyBreakFirstLessLess: 120
> +PenaltyBreakString: 1000
> +PenaltyExcessCharacter: 1000000
> +PenaltyReturnTypeOnItsOwnLine: 60
> +PointerAlignment: Right
> +ReflowComments:  true
> +SortIncludes:    false
> +SortUsingDeclarations: true
> +SpaceAfterCStyleCast: true
> +SpaceAfterLogicalNot: false
> +SpaceBeforeAssignmentOperators: true
> +SpaceBeforeCpp11BracedList: false
> +SpaceBeforeCtorInitializerColon: true
> +SpaceBeforeInheritanceColon: true
> +SpaceBeforeParens: Always
> +SpaceBeforeRangeBasedForLoopColon: true
> +SpaceInEmptyBlock: false
> +SpaceInEmptyParentheses: false
> +SpacesBeforeTrailingComments: 1
> +SpacesInAngles:  false
> +SpacesInConditionalStatement: false
> +SpacesInContainerLiterals: true
> +SpacesInCStyleCastParentheses: false
> +SpacesInParentheses: false
> +SpacesInSquareBrackets: false
> +SpaceBeforeSquareBrackets: false
> +Standard:        Cpp03

OK. Removed StatementMacro use for QT. Resolves Florian's comments in v3.

> +TabWidth:        8
> +UseTab:          Always

OK. Resolved Florian's comments in v3.

> +ForEachMacros:
> +  - 'FOR_EACH_IMPL'
> +  - 'list_for_each'
> +  - 'list_for_each_prev'
> +  - 'list_for_each_prev_safe'
> +...

OK.
  

On Mon, Apr 4, 2022 at 9:13 AM Carlos O'Donell <carlos@redhat.com> wrote:
>
> On 3/30/22 16:24, Noah Goldstein via Libc-alpha wrote:
> > Went with version >= 11.0 since it covers most of the major features
> > and should be pretty universally accessibly.
>
> Almost there. I think with v6 we'll have a version we can commit.
>
> Thanks for iterating.
>
> > There are some issues:
> >
> > 1.  indention of preprocessor directives:
> >     Unfortunately there doesn't appear to be a switch for a seperate
> >     'IndentWidth' for preprocessor directives vs. normal code so we
> >     are stuck either not indenting the directives or over-indenting
> >     them. i.e:
> >     Desired:
> >     ```
> >     #ifndef A
> >     # define B
> >     #endif
> >     ```
> >     Options:
> >     ```
> >     #ifndef A
> >     #  define B /* Two spaces instead of one.  */
> >     #endif
> >
> >     #ifndef C
> >     #define D   /* No spaces.  */
> >     #endif
> >     ```
> >     Chose to over-indent as it generally seems easier to script
> >     halving all pre-processor indentations than counting the nested
> >     depth and indenting from scratch.
> >
> > 2.  concatenation of lines missing semi-colons:
> >     Throughout glibc there are macros used to setup aliasing that are
> >     outside of functions and don't end in semi-colons i.e:
> >     ```
> >     libc_hidden_def (__pthread_self)
> >     weak_alias (__pthread_self, pthread_self)
> >     ```
> >
> >     clang-format reformats lines like these to:
> >     ```
> >     libc_hidden_def (__pthread_self) weak_alias (__pthread_self, pthread_self)
> >     ```
> >
> >     which is generally undesirable.
> >
> > Other than those two big concerns there are certainly some questions
> > diffs but for the most part it creates a easy to read and consistent
> > style.
> > ---
> >  .clang-format | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 156 insertions(+)
> >  create mode 100644 .clang-format
> >
> > diff --git a/.clang-format b/.clang-format
> > new file mode 100644
> > index 0000000000..c0d993fd03
> > --- /dev/null
> > +++ b/.clang-format
> > @@ -0,0 +1,156 @@
> > +#  clang-format file for GLIBC
> > +#  Copyright (C) 2022 Free Software Foundation, Inc.
> > +#  This file is part of the GNU C Library.
> > +#
> > +#  The GNU C Library is free software; you can redistribute it and/or
> > +#  modify it under the terms of the GNU Lesser General Public
> > +#  License as published by the Free Software Foundation; either
> > +#  version 2.1 of the License, or (at your option) any later version.
> > +#
> > +#  The GNU C Library is distributed in the hope that it will be useful,
> > +#  but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +#  Lesser General Public License for more details.
> > +#
> > +#  You should have received a copy of the GNU Lesser General Public
> > +#  License along with the GNU C Library; if not, see
> > +#  <https://www.gnu.org/licenses/>.
> > +#
> > +#  Requires clang-format version >= 11.0
> > +#
> > +#  For more information, see:
> > +#
> > +#   Documentation/process/clang-format.rst
>
> This is not a valid path in the glibc source tree.

Removed that comment. Think the online documentation is enough.
>
> > +#   https://clang.llvm.org/docs/ClangFormat.html
> > +#   https://clang.llvm.org/docs/ClangFormatStyleOptions.html
> > +#
> > +#  There are some known cases that this doesn't produce the desired
> > +#  style (i.e Preprocessor Directives are over-indented and not
> > +#  auto-commented). As a result, this is meant to be a utility to make
> > +#  formatting easier, not a definitive standard.
> > +#
> > +#  To format the current git diff inplace (-i) the follow command can
> > +#  be used:
> > +#  $> git diff -U0 --no-color HEAD^ | clang-format-diff -i -p1
> > +#
> > +#  To just view the diff clang-format would generate:
> > +#  $> git diff -U0 --no-color HEAD^ | clang-format-diff -p1
> > +#
> > +#  NB: clang-format-diff, along with other clang-format related tools,
> > +#      can be found at: /path/to/llvm-project/clang/tools/clang-format/
> > +#
> > +#
> > +---
> > +# BasedOnStyle:  GNU
>
> Suggest:
>
> # This file is based on the existing GNU style e.g. BasedOnStyle:  GNU.
>
> Otherwise developers will be confused why the directive is commented out.

Removed this and added comment in the header clarifying.
>
> > +AccessModifierOffset: -2
> > +AlignAfterOpenBracket: Align
> > +AlignConsecutiveMacros: false
> > +AlignConsecutiveAssignments: false
> > +AlignConsecutiveBitFields: false
> > +AlignConsecutiveDeclarations: false
> > +AlignEscapedNewlines: Right
> > +AlignOperands:   true
> > +AlignTrailingComments: true
> > +AllowAllArgumentsOnNextLine: true
> > +AllowAllParametersOfDeclarationOnNextLine: true
> > +AllowShortEnumsOnASingleLine: true
> > +AllowShortBlocksOnASingleLine: false
> > +AllowShortCaseLabelsOnASingleLine: false
> > +AllowShortFunctionsOnASingleLine: All
> > +AllowShortLambdasOnASingleLine: All
> > +AllowShortIfStatementsOnASingleLine: Never
> > +AllowShortLoopsOnASingleLine: false
> > +AlwaysBreakAfterDefinitionReturnType: All
> > +AlwaysBreakAfterReturnType: AllDefinitions
> > +AlwaysBreakBeforeMultilineStrings: false
> > +BinPackArguments: true
> > +BinPackParameters: true
> > +BraceWrapping:
> > +  AfterCaseLabel:  true
> > +  AfterClass:      true
> > +  AfterControlStatement: true
> > +  AfterEnum:       true
> > +  AfterFunction:   true
> > +  AfterNamespace:  true
> > +  AfterStruct:     true
> > +  AfterUnion:      true
> > +  AfterExternBlock: true
> > +  BeforeCatch:     true
> > +  BeforeElse:      true
> > +  BeforeWhile:     true
> > +  IndentBraces:    true
> > +  SplitEmptyFunction: true
> > +  SplitEmptyRecord: true
> > +  SplitEmptyNamespace: true
> > +BreakBeforeBinaryOperators: All
> > +BreakBeforeBraces: GNU
> > +BreakBeforeInheritanceComma: false
> > +BreakInheritanceList: BeforeColon
> > +BreakBeforeTernaryOperators: true
> > +BreakStringLiterals: true
> > +ColumnLimit:     79
> > +CommentPragmas:  '^ IWYU pragma:'
> > +CompactNamespaces: false
> > +ContinuationIndentWidth: 4
> > +Cpp11BracedListStyle: false
> > +DeriveLineEnding: true
> > +DerivePointerAlignment: false
> > +DisableFormat:   false
> > +ExperimentalAutoDetectBinPacking: false
> > +FixNamespaceComments: false
> > +IncludeBlocks:   Preserve
> > +IncludeCategories:
> > +  - Regex:           '.*'
> > +    Priority:        1
>
> OK. Resolves Florian's comment regarding IncludeCategories.
>
> > +IncludeIsMainRegex: '(Test)?$'
> > +IndentCaseLabels: false
> > +IndentCaseBlocks: false
> > +IndentGotoLabels: true
> > +IndentWidth:     2
> > +IndentPPDirectives: AfterHash
> > +IndentExternBlock: AfterExternBlock
> > +IndentWrappedFunctionNames: false
> > +InsertTrailingCommas: None
> > +KeepEmptyLinesAtTheStartOfBlocks: true
> > +MacroBlockBegin: ''
> > +MacroBlockEnd:   ''
> > +MaxEmptyLinesToKeep: 1
> > +NamespaceIndentation: None
> > +PenaltyBreakAssignment: 2
> > +PenaltyBreakBeforeFirstCallParameter: 19
> > +PenaltyBreakComment: 300
> > +PenaltyBreakFirstLessLess: 120
> > +PenaltyBreakString: 1000
> > +PenaltyExcessCharacter: 1000000
> > +PenaltyReturnTypeOnItsOwnLine: 60
> > +PointerAlignment: Right
> > +ReflowComments:  true
> > +SortIncludes:    false
> > +SortUsingDeclarations: true
> > +SpaceAfterCStyleCast: true
> > +SpaceAfterLogicalNot: false
> > +SpaceBeforeAssignmentOperators: true
> > +SpaceBeforeCpp11BracedList: false
> > +SpaceBeforeCtorInitializerColon: true
> > +SpaceBeforeInheritanceColon: true
> > +SpaceBeforeParens: Always
> > +SpaceBeforeRangeBasedForLoopColon: true
> > +SpaceInEmptyBlock: false
> > +SpaceInEmptyParentheses: false
> > +SpacesBeforeTrailingComments: 1
> > +SpacesInAngles:  false
> > +SpacesInConditionalStatement: false
> > +SpacesInContainerLiterals: true
> > +SpacesInCStyleCastParentheses: false
> > +SpacesInParentheses: false
> > +SpacesInSquareBrackets: false
> > +SpaceBeforeSquareBrackets: false
> > +Standard:        Cpp03
>
> OK. Removed StatementMacro use for QT. Resolves Florian's comments in v3.
>
> > +TabWidth:        8
> > +UseTab:          Always
>
> OK. Resolved Florian's comments in v3.
>
> > +ForEachMacros:
> > +  - 'FOR_EACH_IMPL'
> > +  - 'list_for_each'
> > +  - 'list_for_each_prev'
> > +  - 'list_for_each_prev_safe'
> > +...
>
> OK.
>
> --
> Cheers,
> Carlos.
>