Subject: Re: [PATCH 3/4] cmake: add a preparatory work-around to accommodate `vcpkg`

From: Đoàn Trần Công Danh <[email-masked]>
Date: Sun, 28 Mar 2021 10:19:51 +0700

On 2021-03-27 23:06:24+0000, Johannes Schindelin via GitGitGadget <[email-masked]> wrote:
> From: Johannes Schindelin <[email-masked]>
> 
> We are about to add support for installing the `.dll` files of Git's
> dependencies (such as libcurl) in the CMake configuration. The `vcpkg`
> ecosystem from which we get said dependencies makes that relatively
> easy: simply turn on `X_VCPKG_APPLOCAL_DEPS_INSTALL`.
> 
> However, current `vcpkg` introduces a limitation if one does that:
> While it is totally cool with CMake to specify multiple targets within
> one invocation of `install(TARGETS ...) (at least according to
> https://cmake.org/cmake/help/latest/command/install.html#command:install),
> `vcpkg`'s parser insists on a single target per `install(TARGETS ...)`
> invocation.
> 
> Well, that's easily accomplished: Let's feed the targets individually to
> the `install(TARGETS ...)` function in a `foreach()` look.
> 
> This also has the advantage that we do not have to manually cull off the
> two entries from the `${PROGRAMS_BUILT}` array before scheduling the
> remainder to be installed into `libexec/git-core`. Instead, we iterate
> through the array and decide for each entry where it wants to go.
> 
> Signed-off-by: Johannes Schindelin <[email-masked]>
> ---
>  contrib/buildsystems/CMakeLists.txt | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt
> index da2811ae3aad..a166be0eb1b8 100644
> --- a/contrib/buildsystems/CMakeLists.txt
> +++ b/contrib/buildsystems/CMakeLists.txt
> @@ -811,15 +811,19 @@ list(TRANSFORM git_shell_scripts PREPEND "${CMAKE_BINARY_DIR}/")
>  list(TRANSFORM git_perl_scripts PREPEND "${CMAKE_BINARY_DIR}/")
>  
>  #install
> -install(TARGETS git git-shell
> +foreach(program ${PROGRAMS_BUILT})
> +if(${program} STREQUAL git OR ${program} STREQUAL git-shell)

Please don't use `${}` around variable inside `if()`, and quote the
string. CMake has a quirk with the `${}` inside if (expanded variable
will be treated as a variable if it is defined, or string otherwise).
Unquoted string will be seen as a variable if it's defined, string
otherwise. IOW, suggested command:

	if (program STREQUAL "git" OR program STREQUAL "git-shell")

We also have another problem with quoted arguments could be interpreted
as variable or keyword if CMP0054 policy not enabled, too.
I think it's better to have it enabled, but it's not in the scope of
this patch.

 https://cmake.org/cmake/help/latest/policy/CMP0054.html

-- 
Danh