[Hackage] #262: Check for required C libraries during configure
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: normal | Milestone: Component: Cabal library | Version: 1.2.3.0 Severity: normal | Keywords: Difficulty: normal | Ghcversion: 6.8.2 Platform: | ----------------------------+----------------------------------------------- Cabal should check for required C libraries and other non-Haskell dependencies at the configure stage, rather than just waiting for the linker to fail with an obscure error message during the build stage. Error messages should be helpful for the typical Cabal user, who should not be assumed to know anything about C libraries or linking. That is not so simple. For example: The haddock package current requires the C libraries for readline, due to its dependency on the GHC API. If that library is missing, the user should have some way of figuring out how do the right thing on the given platform - for most Linux distros, install the readline-dev package (as opposed to just readline), for Mac OS X download the GNUreadline framework from the GHC website and drag it into the appropriate Frameworks folder depending on whether this is Tiger and below or Leopard and above, etc. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: normal | Milestone: Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: normal Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Comment (by guest): See also: * #15 and #159 - implement dependency analysis * #216 - specify more kinds of dependencies in .cabal files * #177 - check for required directories -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:1 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: normal | Milestone: Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: normal Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Comment (by duncan): I don't think the dependency analysis tickets are relevant here. Just knowing the required C headers and C libs and the include and library search paths is enough information to do the checks. It's just the same check that autoconf does and we can do it in a similar way. I'm not sure that being able to specify the foreign package dependencies would help here as we don't have a platform independent way of checking for them anyway. Those are more hints for package managers I'd say. So we should look up exactly how autoconf does these checks. My understanding is: * for headers it makes a small .c file that #includes the header and calls gcc/cpp to process the file. It passes the extra include search dirs with the -I flag. * for libs it makes a small .o file and calls gcc/ld with the -l and -L flags. If they fail then it means we cannot find the header/lib in question. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:2 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: normal | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: normal Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Changes (by duncan): * milestone: => Cabal-1.6 -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:3 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Changes (by duncan): * priority: normal => high * difficulty: normal => easy (<4 hours) -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:4 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Changes (by guest): * cc: gwern0@gmail.com (added) -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:5 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Comment (by duncan): I've been thinking about this and I think that with packages that use confiure scripts there is actually no point at which we can do this check. The reason is that we need any extra settings from the `.buildinfo` file, however that file is generated by `./configure` and the `Setup.hs` script never sees it. In fact the first point we could see the full information is during `preBuild`, we could not do the check during configure at all. We could try and hack it by reading the `.buildinfo` file directly during `postConf` but that's pretty hairy since the user can modify the hooks however they like and there is no requirement that they use any particular file. So we may have to only do this check for `build-type: Simple`. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:6 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Changes (by tanimoto): * cc: tanimoto@arizona.edu (added) -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:7 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Changes (by jeffwheeler): * cc: jeff@nokrev.com (added) -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:8 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Comment (by alexeevg):
we should look up exactly how autoconf does these checks
I started looking into it and stumbled upon a little problem. Maybe it's a silly question, but I'm going to ask it anyway. Autoconf uses AC_CHECK_LIB macro to check if the library is present. AC_CHECK_LIB takes the library name and a function(symbol) name that is expected to be exported from the library, generates a C program depending on this symbol and tries compiling it. This is a bit of info we miss in BuildInfo - we have extra- libs, but no function names.
Error messages should be helpful for the typical Cabal user, who should not be assumed to know > anything about C libraries or linking.
This is a bit unclear to me - we have no info on required packages, we have only includes/extra-libs, how do we make error messages user- friendly? Autoconf doesn't do it. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:9 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
This is a bit of info we miss in BuildInfo? - we have extra-libs, but no function names. Hmm, it seems that Autoconf is a little paranoid here, ld will fail if
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Comment (by alexeevg): Answering my own question: library is not found regardless of whether or not the program depends on it. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:10 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Comment (by duncan): Replying to [comment:9 alexeevg]:
Autoconf uses AC_CHECK_LIB macro to check if the library is present. AC_CHECK_LIB takes the library name and a function(symbol) name that is expected to be exported from the library, generates a C program depending on this symbol and tries compiling it. This is a bit of info we miss in BuildInfo - we have extra-libs, but no function names.
Right, we do not have this additional information. As you say, we will have to rely on `ld` being paranoid and failing when it cannot find a library, even if the object files do not depend on any function exported by that library. Actually, I think ld pretty much has to have this behavior since it does not know what symbols the missing library might export that would shadow symbols exported by other libraries. So it cannot actually determine if the library is not needed, at least for ELF linkers.
Error messages should be helpful for the typical Cabal user, who should not be assumed to know > anything about C libraries or linking.
This is a bit unclear to me - we have no info on required packages, we have only includes/extra-libs, how do we make error messages user- friendly? Autoconf doesn't do it.
You're right that we cannot easily or accurately map missing C libs back to which native OS packages that provide them. I think we can still produce reasonable error messages. We can at least explain which C libraries are missing, we must make it clear that these are C libraries (not Haskell packages) that we expected to find on the system. Then there are two possible causes with corresponding solutions: * The most likely is that the C package is just not installed, or that the development flavour of the package is not installed (binary Linux distros often split packages into runtime and dev variants). We can recommend users look for a native package with a similar name to the C lib, and if there is a "-dev" version then install that. We could provide more detail and say the native package should provide a file `libfoo.so` or `libfoo.a` or whatever. * Another possibility is that the C lib is installed but in some non- standard location. In that case we should tell users about the `--extra- include-dirs` and/or `--extra-lib-dirs` flags. Just for my own future reference: * [http://www.gnu.org/software/hello/manual/autoconf/Libraries.html AC_CHECK_LIB] * [http://www.gnu.org/software/hello/manual/autoconf/Generic- Headers.html AC_CHECK_HEADER] -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:11 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: new Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Comment (by duncan): Now partially done! -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:12 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure
----------------------------+-----------------------------------------------
Reporter: guest | Owner:
Type: enhancement | Status: new
Priority: high | Milestone: Cabal-1.6
Component: Cabal library | Version: 1.2.3.0
Severity: normal | Resolution:
Keywords: | Difficulty: very easy (<1 hour)
Ghcversion: 6.8.2 | Platform:
----------------------------+-----------------------------------------------
Changes (by duncan):
* difficulty: easy (<4 hours) => very easy (<1 hour)
Comment:
Thanks! Works great.
For example:
{{{
$ setup configure -O0
Configuring foo-1.0...
Warning: Required C header not found: foo.h
Warning: Required C library not found: bar
Warning: Required C library not found: baz
}}}
And adding `--extra-include-dirs=./test/ --extra-lib-dirs=./test/` makes
it work fine (with the test headers and lib files in `./test/` obviously).
{{{
Mon Jan 26 18:58:32 GMT 2009 gleb.alexeev@gmail.com
* Warn if C dependencies not found (kind of fixes #262)
This is just a basic check - generate a sample program and check if it
compiles and links with relevant flags. Error messages (warning messages,
actually) could use some improvement.
Fri Jan 30 12:02:28 GMT 2009 Gleb Alexeyev
#262: Check for required C libraries during configure
----------------------------+-----------------------------------------------
Reporter: guest | Owner:
Type: enhancement | Status: closed
Priority: high | Milestone: Cabal-1.6
Component: Cabal library | Version: 1.2.3.0
Severity: normal | Resolution: fixed
Keywords: | Difficulty: very easy (<1 hour)
Ghcversion: 6.8.2 | Platform:
----------------------------+-----------------------------------------------
Changes (by duncan):
* status: new => closed
* resolution: => fixed
Comment:
The check is now done after running `./configure` so we can pick up any
settings it provides. Those settings (`cpp-options`, `cc-options` and `ld-
options`) are also now taken into account. This means the check should now
be accurate so we can make it fatal rather than a warning. This is
important to help people identify the cause of the problem.
{{{
Sat Jan 31 18:22:13 GMT 2009 Duncan Coutts
#262: Check for required C libraries during configure ----------------------------+----------------------------------------------- Reporter: guest | Owner: Type: enhancement | Status: reopened Priority: high | Milestone: Cabal-1.6 Component: Cabal library | Version: 1.2.3.0 Severity: normal | Resolution: Keywords: | Difficulty: easy (<4 hours) Ghcversion: 6.8.2 | Platform: ----------------------------+----------------------------------------------- Changes (by duncan): * status: closed => reopened * difficulty: very easy (<1 hour) => easy (<4 hours) * resolution: fixed => Comment: I've built nearly every package on hackage to look for regressions. Two things need fixing: We do not look for `.h` files in the root directory of the package. This breaks `HsPerl5-0.0.6`, `cedict-0.2.5` and `halfs-0.2`. We do not add the include dirs for dependent packages. This breaks `hscurses-1.3.0.2`, `plugins-1.4.0` and `unix-compat-0.1.2.1`. Of these `plugins-1.4.0` is not a good test case because it is broken for other reasons (the .h file it #includes cannot be included on its own). The solution to the first issue should be easy. Just add `.` into the list of include dirs. The second requires copying the code from the pre- processor module where we do the same thing for hsc2hs. Perhaps it's possible to share the code. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/262#comment:15 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects
#262: Check for required C libraries during configure
----------------------------+-----------------------------------------------
Reporter: guest | Owner:
Type: enhancement | Status: closed
Priority: high | Milestone: Cabal-1.6
Component: Cabal library | Version: 1.2.3.0
Severity: normal | Resolution: fixed
Keywords: | Difficulty: easy (<4 hours)
Ghcversion: 6.8.2 | Platform:
----------------------------+-----------------------------------------------
Changes (by duncan):
* status: reopened => closed
* resolution: => fixed
Comment:
Fixed.
{{{
Wed Feb 18 11:05:20 GMT 2009 Duncan Coutts
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