clang-format option InsertNewlineAtEOF does not add newline

[jasonfsmitty]

On Fedora 36, running a local build from source of LLVM 16.0.4

The clang format option InsertNewlineAtEOF : true is not being applied, instead the newline is being removed:

[smithj1]$ /opt/llvm-16.0.4/bin/clang-format --version
clang-format version 16.0.4
[smithj1]$ printf "namespace aaa {}\n\n"
namespace aaa {}

[smithj1]$ printf "namespace aaa {}\n\n" | /opt/llvm-16.0.4/bin/clang-format --style="{ InsertNewlineAtEOF : true }"
namespace aaa {}
[smithj1]$ printf "namespace aaa {}\n\n" | /opt/llvm-16.0.4/bin/clang-format --style="{ InsertNewlineAtEOF : false }"
namespace aaa {}
[smithj1]$

This also happens in our codebase, where we leverage .clang-format files to auto-format sections of our repo:

[smithj1]$ grep NewlineAtEOF .clang-format 
InsertNewlineAtEOF: true
[smithj1]$ cat test.cpp 
#include <iostream>

int main(int argc, char* argv[])
{
	std::cout << "Hello World" << std::endl;
	return 0;
}

[smithj1]$ /opt/llvm-16.0.4/bin/clang-format --style=file -Werror test.cpp 
#include <iostream>

int main(int argc, char* argv[])
{
	std::cout << "Hello World" << std::endl;
	return 0;
}
[smithj1]$

One counter-point that I can't explain, is that clang-format does format properly when using plugins in VS Code and vim.

For vim, I'm using the vim-clang-format plugin, with the following in .vimrc:

let g:clang_format#command = "/opt/llvm-16.0.4/bin/clang-format"
let g:clang_format#auto_format = 1
let g:clang_format#detect_style_file = 1
let g:clang_format#auto_filetypes = [ "c", "cpp" ]
let g:clang_format#enable_fallback_style = 0

If I open a file and save it with vim, it formats the file correctly including adding the newline at EOF.

[jasonfsmitty]

#56054 is related (it's where I got the 'namespace aaa {}' example), but I think that request pre-dates the 16.0.0 release, which added the InsertNewlineAtEOF option.

#61551 is also asking for a newline at EOF, but the response refers the submitter to InsertNewlineAtEOF and was closed.

[llvmbot]

@llvm/issue-subscribers-clang-format

[owenca]

On Fedora 36, running a local build from source of LLVM 16.0.4

The clang format option InsertNewlineAtEOF : true is not being applied, instead the newline is being removed:

[smithj1]$ /opt/llvm-16.0.4/bin/clang-format --version
clang-format version 16.0.4
[smithj1]$ printf "namespace aaa {}\n\n"
namespace aaa {}

[smithj1]$ printf "namespace aaa {}\n\n" | /opt/llvm-16.0.4/bin/clang-format --style="{ InsertNewlineAtEOF : true }"
namespace aaa {}
[smithj1]$ printf "namespace aaa {}\n\n" | /opt/llvm-16.0.4/bin/clang-format --style="{ InsertNewlineAtEOF : false }"
namespace aaa {}
[smithj1]$

InsertNewlineAtEOF inserts a newline only if the input doesn't end with one:

$ printf "namespace aaa {}"
namespace aaa {}$ printf "namespace aaa {}" | clang-format -style='{InsertNewlineAtEOF: true}'
namespace aaa {}
$ printf "namespace aaa {}\n"
namespace aaa {}
$ printf "namespace aaa {}\n" | clang-format -style='{InsertNewlineAtEOF: true}'
namespace aaa {}
$ 

It seems that clang-format always removes empty lines at the end of the input. Please file another issue if you believe it shouldn't.

[owenca]

https://reviews.llvm.org/D152305