Configure uses which which is not POSIX compliant

[Kangie]

Issue

checking FLTK 1.3... yes
checking whether to link to X11... yes
checking for jpeglib.h... yes
checking for jpeg_destroy_decompress in -ljpeg... yes
checking for zlib.h... yes
checking for zlibVersion in -lz... yes
checking for libpng-config... ./configure: line 7202: which: command not found
./configure: line 7204: which: command not found
./configure: line 7207: which: command not found

which is not listed as a required command by POSIX and should be replaced by command -v.

See also: https://bugs.gentoo.org/940568

Reproducing

Attempt to configure dillo on a machine without which.

Resolution

Exorcise which from the codebase.

Examples:

dillo/autogen.sh

Line 18 in 4f30333

which $1 > /dev/null 2>&1

dillo/configure.ac

Lines 298 to 313 in 4f30333

	dnl Check if the user hasn't set the variable $PNG_CONFIG
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng16-config`
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng14-config`
	fi
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng12-config`
	fi
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng-config`
	fi
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng10-config`
	fi
	fi

[Kangie]

Would you accept a PR that switched to the meson build system rather than patching autotools?

It will prove to be more maintainable, will eliminate this issue entirely, and in terms of 'needs to run anywhere' there are muon and samurai which are C99 implementations of Meson and Ninja respectively.

[Kangie]

Re:

dillo/configure.ac

Lines 298 to 313 in 4f30333

	dnl Check if the user hasn't set the variable $PNG_CONFIG
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng16-config`
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng14-config`
	fi
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng12-config`
	fi
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng-config`
	fi
	if test -z "$PNG_CONFIG"; then
	PNG_CONFIG=`which libpng10-config`
	fi
	fi

If autotools is to be retained this whole section (and the checks afterwards) could be trivially simplified to 'query pkg-config'.

[rodarima]

I commented on the meson build in the PR. Let's keep this issue to solve only the problem of removing which to command -v, which should be fairly easy to do.

We don't have a build dependency over pkg-config, so I don't think this particular problem needs to pull it.

[eli-schwartz]

Instead of using command -v, there is preexisting code earlier in this file:

AC_PATH_PROG(FLTK_CONFIG,fltk-config)

indicating the correct way to check for a program while respecting pre-set environment variables, is already known.

We don't have a build dependency over pkg-config, so I don't think this particular problem needs to pull it.

"which" isn't the problem that is solved by using pkg-config. You still have to check for and find pkg-config as well.

The problem that is solved by using pkg-config is the cross-compilation problem. :) There are plenty of other dependencies that can use the same treatment... openssl, zlib, jpeg...

[eli-schwartz]

It's possible to check pkg-config first and fall back to foobar-config programs only when that fails.

[rodarima]

...indicating the correct way to check for a program...

The which command is not needed, so I prefer to switch to command -v which should be available in a POSIX shell.

The problem that is solved by using pkg-config is the cross-compilation problem

Then I recommend you address it in another issue. I think this may also help #258 and #34. It would be nice to have a cross-compilation build in the CI, but I'm not sure if I know how to set it up.

[rodarima]

Fixed in 9880c1b