clarifying semantics of pkg-config field in .cabal files

[cartazio]

@dcoutts @ezyang @hvr et al,
what are the desired semantics for the
pkgconfig: libtls >= bound ...
stanzas in foo.cabal package descriptions.

it looks like i, the end user for a package, need to do an
export PKG_CONFIG_PATH=/usr/local/opt/libressl/lib/pkgconfig
stanza in my terminal to get things to work out ok. Is there any way to hint to pkg-config what paths to look at per platform or must it always be totally user setup? (the current error messages look quite confusing when the stars aren't aligned)

an example might be JustinTulloss/zeromq.node#283 (comment) for another ecosystem. likewise https://groups.google.com/forum/#!topic/haskell-stack/E6zGmRnT3Ls

or perhaps i'm just not understanding what i should be doing :)

[hvr]

IMO, pkg-config is a system-tool and your environment is responsible to set its configuration up in a way that calling pkg-config --list-all shows everything registered w/ pkg-config. The point of pkg-config is so that you don't have to know where stuff is installed, cause pkg-config keeps that information for you. If you need a specific PKG_CONFIG_PATH then either your system installation of pkg-config is broken or you have manually installed & setup pkg-config and you need to take care yourself in e.g. your ~/.profile to set the PKG_CONFIG_PATH env-var.

[cartazio]

This is a valid opinion. It's just not documented so I had to ask

…

On Wed, Jan 18, 2017 at 2:36 AM Herbert Valerio Riedel < ***@***.***> wrote: IMO, pkg-config is a system-tool and your environment is responsible to set its configuration up in a way that calling pkg-config --list-all shows everything registered w/ pkg-config. The point of pkg-config is so that you don't have to know where stuff is installed, cause pkg-config keeps that information for you. If you need a specific PKG_CONFIG_PATH then either your system installation of pkg-config is broken or you have manually installed & setup pkg-config and you need to take care yourself in e.g. your ~/.profile to set the PKG_CONFIG_PATH env-var. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#4242 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAQwvpJm1OfJVirp1tWiE7V3IJbnW_Iks5rTcEagaJpZM4LlNDH> .

[cartazio]

Also it's hard to find good docs on pkg config or I've been looking in the wrong places On Wed, Jan 18, 2017 at 5:31 PM Carter Schonwald <carter.schonwald@gmail.com> wrote:

…

This is a valid opinion. It's just not documented so I had to ask On Wed, Jan 18, 2017 at 2:36 AM Herbert Valerio Riedel < ***@***.***> wrote: IMO, pkg-config is a system-tool and your environment is responsible to set its configuration up in a way that calling pkg-config --list-all shows everything registered w/ pkg-config. The point of pkg-config is so that you don't have to know where stuff is installed, cause pkg-config keeps that information for you. If you need a specific PKG_CONFIG_PATH then either your system installation of pkg-config is broken or you have manually installed & setup pkg-config and you need to take care yourself in e.g. your ~/.profile to set the PKG_CONFIG_PATH env-var. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#4242 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAQwvpJm1OfJVirp1tWiE7V3IJbnW_Iks5rTcEagaJpZM4LlNDH> .

[ezyang]

@carter, @hvr, is there a simple documentation patch the two of you could put together which would clarify this behavior, in the Cabal manual? Thanks!