I use :make to run a python script to build a C++ project. Usually, the output errors are C++ errors and :compiler msvc parses them correctly. Rarely, the error is a python one and I want :compiler python instead.

Is it possible to re-parse the quickfix with a different errorformat without re-running the command that generated the output?

The best solution I've got is to hope the python lines survived as unrecognized lines (prefixed with || and load them out of the quickfix buffer, but this seems brittle:

:copen | 0,$yank | new | put | %s/^|| // | compiler python | cgetbuffer | bdelete! | nohlsearch
  • I think when quickfix throws lines away, they’re gone, but you could use the quickfix functions to process the entries? Or combine the errorformats? (PS :%yank)
    – D. Ben Knoble
    Commented Oct 10, 2023 at 22:05

2 Answers 2


Your use case is a special one that is not fully covered by either :compiler msvc or :compiler python so making your own "compiler" seems to make the most sense. Now, how to go about it?

The errorformat set in $VIMRUNTIME/compiler/msvc.vim is simply the default one.

The errorformat set in your third-party script completely replaces the default value with a custom one.

One thing I would try would be to replace the = in:

CompilerSet errorformat=%A%\\s%#File\ \"%f\"\\,\ line\ %l\\,\ in%.%#

with a += and see how it goes. This would append the custom errorformat to the default one and, presumably, match both the C++ errors and the Python ones.

The drawback, here, would be that errorformat is a rather large comma-seprated list of values that are tried in order, which can give you false positives. Maybe you could identify the value(s) that effectively match your C++ errors (say %f:%l:%c:%m) and do something like:

" in compiler/mine.vim
CompilerSet errorformat=%f:%l:%c:%m
CompilerSet errorformat+=%A%\\s%#File\ \"%f\"\\,\ line\ %l\\,\ in%.%#
  • I was hoping for a post-process solution, but I guess that information is lost? This is helpful, but don't I need to explicitly set efm& in case efm already changed? Also, I don't think I'd want other invocations of python to recognize msvc errors, but I guess I could make a new compiler/pybuild.vim that merges the two together with something like: compiler msvc | let c_ef = &efm | compiler python | let &efm=c_ef ..','..&efm (maybe needs unlet current_compiler too...). Thanks for the answer!
    – idbrii
    Commented Oct 12, 2023 at 17:31

I didn't want to copypaste the contents of my (custom) compiler/msvc.vim and compiler/python.vim into another file, so instead I found a solution that combines the C++ and python errorformat and uses the python makeprg.

Saved as ~/.vim/compiler/py_msvc.vim:

" Compiler: python that builds C++ with msvc

if exists("current_compiler")

" Use :runtime because :compiler makes vim setup CompilerSet which errors if
" it's already setup.
runtime compiler/msvc.vim
silent! unlet g:current_compiler
let c_ef = &errorformat

runtime compiler/python.vim
silent! unlet g:current_compiler

" Prepend so C errors are recognized first.
let &errorformat=c_ef ..','..&errorformat

let g:current_compiler = 'py_msvc'

" vim:set sw=2 sts=2:

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