meson: fix handling of '-Dcurl=auto'

The "curl" option controls whether or not a couple of features that
depend on curl shall be included. Most importantly, these features
include the HTTP remote helpers, which are rather quintessential for a
well-functioning Git installation. So while the dependency can in theory
be dropped, most users wouldn't consider the resulting installation to
be fully functional.

The "curl" option is defined as a feature, which means that it can be
"enabled", "disabled" or "auto", which has the effect that the feature
will be enabled if the dependency itself has been found. While most of
the other features have "auto" as default value, the "curl" option is
set to "enabled" by default due to it being so important. Consequently,
autoconfiguration of Git will fail by default if the library cannot be
found.

There is a bug though with how we handle the option in case the user
overrides the feature with `meson setup -Dcurl=auto`: while we will try
to find the library in that case, we won't ever use it because we later
on check for `get_option('curl').enabled()` when deciding whether or not
we want to build dependent sources. But `enabled()` only returns true if
the option has the value "enabled", for "auto" it will return false.

Fix the issue by instead checking for `curl.found()`, which is only true
if the library has been found. And as we only try to find the library
when `get_option('curl')` returns "true" or "auto" this is exactly what
we want.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

meson.build

@@ -1686,7 +1686,7 @@ bin_wrappers += executable('scalar',
   install_dir: get_option('libexecdir') / 'git-core',
 )
 
-if get_option('curl').enabled()
+if curl.found()
   libgit_curl = declare_dependency(
     sources: [
       'http.c',