llvm dev - Jun 2013 - [LLVMdev] clang-format: `AlwaysBreakTemplateDeclarations: true` for LLVMStyle?

Hi guys,

Is the current setting of `AlwaysBreakTemplateDeclarations: false` for
LLVMStyle intentional? What was the rationale?

Some rough counts on the LLVM codebase:

same-line:
$ git grep -E 'template.*(class|struct).*{' -- '*.h'
'*.cpp' | wc -l
214

(most of them are tiny traits classes, like isPodLike or DenseMapInfo)

not-same-line:
$ git grep -A1 -h 'template' -- '*.h' '*.cpp' | egrep
'^\s*(class|struct).*{' | wc -l
622

Recently, when using clang-format I've had to manually go back and change
cases where clang-format does not put the `template <...>` on its own
line.
I know that I could write a local .clang-format for this, but I think it
should be in the LLVMStyle to begin with (barring this choice being
intentional and having a reasonable rationale).

-- Sean Silva
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The rationale is that we introduced this option (before it was always
'false') and we did not know what the desired behavior for LLVM style
is.
Thus, we opted for not changing clang-format's behavior.

Your numbers show to some extend that other developers are also not clear
on this (3:1 is far from a clear decision). Note, that some of the 622
not-same-line-cases might in theory be due to line length making the gap
even smaller (I have not double-checked that, though).

Feel free to change this flag, but I suggest getting the opinions of a few
key contributors first.


On Wed, Jun 26, 2013 at 8:29 PM, Sean Silva <silvas at purdue.edu> wrote:
> Hi guys,
>
> Is the current setting of `AlwaysBreakTemplateDeclarations: false` for
> LLVMStyle intentional? What was the rationale?
>
> Some rough counts on the LLVM codebase:
>
> same-line:
> $ git grep -E 'template.*(class|struct).*{' -- '*.h'
'*.cpp' | wc -l
> 214
>
> (most of them are tiny traits classes, like isPodLike or DenseMapInfo)
>
> not-same-line:
> $ git grep -A1 -h 'template' -- '*.h' '*.cpp' |
egrep
> '^\s*(class|struct).*{' | wc -l
> 622
>
> Recently, when using clang-format I've had to manually go back and
change
> cases where clang-format does not put the `template <...>` on its own
line.
> I know that I could write a local .clang-format for this, but I think it
> should be in the LLVMStyle to begin with (barring this choice being
> intentional and having a reasonable rationale).
>
> -- Sean Silva
>
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