Document the meaning of -i, -hidir, and -odir
Summary
Recently, I discovered that -hidir
clears any attempt to tell to ghc
were to find interface files with -i
.
There seems to be various behaviors that arise in different combinations of these flags as discussed in this thread when using the batch mode as enabled with -c
.
None of these behaviors is documented in the user's guide. The most concrete pieces we have are the definition of the search path, and the documentation of -hidir and -odir.
Some things to note
The documentation says the search path is used to search for source files and interface files. However, it can be readily verified that -i
is also used to search for object files.
The documentation of -hidir <dir>
only says that it makes ghc
output and look for interface files in <dir>
. But -hidir
also has the effect of stopping the search of interface files on any folders specified with -i
.
Similar issues happen with object files when using -odir
.
Ideal outcome
The documentation should explain accurately how ghc
behaves in the presence of these flags. And ideally, there would be a way to control where ghc
looks for interface and object files independently of where output files are placed.
Environment
- GHC version used: 9.2.1 and 8.10.4
Optional:
- Operating System: nixos
- System Architecture: x86_64