GHC can't find library using "short" name
I wanted to build HDBC-postgresql 1.0.1[1] today, and ran into a problem where my test program would not load and instead gave this error:
can't load .so/.DLL for: pq (addDLL: unknown error)I traced this to the 'extra-libraries' directive in the .cabal file. It read
Extra-Libraries: pqWhen I changed it to
Extra-Libraries: libpqThe error went away. Somehow "pq" is not enough to get "libpq.dll" loaded.
Note that building on Windows required some other changes.[2]
This was using Cabal 1.1
[1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HDBC-postgresql-1.0.1.0
[2] From http://software.complete.org/hdbc/wiki/FrequentlyAskedQuestions
To build on Windows, you must specify where the postgresql include and library files are. Follow these two steps:
- Ensure the files are NOT installed in a directory with spaces in the name (e.g. "C:\Program Files"). For example, install them in c:\pgsql.
- Assuming postgresql is installed in C:\pgsql, add the following information to the .cabal file:
include-dirs: C:\pgsql\include, C:\pgsql\include\server, .
extra-lib-dirs: C:\pgsql\binNotice the "." at the end of include-dirs to ensure the current directory is also searched. Also notice "bin" directory is specified in "extra-lib-dirs." This is important in the next step.
- HDBC-postgresl depends on "libpa.dll" in the bin directory above. The .cabal file refers to the "pq", but that doesn't work on Windows. Change it to libpq like so:
Extra-Libraries: libpq
Trac metadata
| Trac field | Value |
|---|---|
| Version | 6.6.1 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |