Certain tools, e.g. compilers, are customarily prefixed with the name of
their target platform so that multiple builds can be used at once
without clobbering each other on the PATH. I was using identifiers named
`prefix` for this purpose, but that conflicts with the standard use of
`prefix` to mean the directory where something is installed. To avoid
conflict and confusion, I renamed those to `targetPrefix`.
If a dynamic linker for target is not found the generated script fails
due to unbound variable error (due to "set -u"). Correct by specifying
default value with dynamicLinker:- and not generating ldflagsBefore if
no linker is found.
This problem was found when cross compiling to mingw32 targets
cc-wrapper may wrap a cc-compiler, but it doesn't need one to build
itself. (c.f. expand-response-params is a separate derivation.) This
helps avoid cycles on the cross stuff, in addition to removing a
useless dependency edge.
I could have been super careful with overrides in the stdenv to avoid
the mass rebuild, but I don't think it's worth it.
1. `crossDrv` is now the default so we don't need to worry about that in
build != host builds.
2. shell is the build time shell, so `wrapCCCross` doesn't need to
worry, as build == host.
3. `shell.shellPath` will always be appended where useful.
4. Complicated `shell == ""` logic served no purpose.
ccPath is only defined below, so this condition would never be true.
Worse, that's not quite true: what if somebody happend to have `/clang`
and no sandboxing. Boy, wouldn't that be annoying to debug!
Having multiple compilers in the build environment would result in an
invalid LD_DYLD_PATH like /usr/lib/dyld/usr/lib/dyld.
Since the path is hardcoded in XNU it can't be anything but
/usr/lib/dyld anyway.
This is an ugly temp hack for cross compilation, but now we have something better on the way.
Bind `infixSalt` as an environment variable as it will be used in it.
As described in https://github.com/NixOS/nixpkgs/issues/18461, MacOS no
longer accepts dylibs which only reexport other dylibs, because their
symbol tables are empty. To get around this, we define an object file
with a single "private extern" symbol, which hopefully won't clobber
anything.
As @oxij points out in [1], this breakage is especially serious because
it changes the contents of built environments without a corresonding
change in their hashes. Also, the revert is easier than I thought.
This reverts commit 3cb745d5a6.
[1]: https://github.com/NixOS/nixpkgs/pull/27427#issuecomment-317293040
Besides deduplicating overlapping logic, clear warning messages were
added for:
- No glob/path for dynamic linker provided (use default glob)
- Glob did not expand to anything (don't append flag)
- glob expanded to multiple things (take first, like before)
This makes those files a bit easier to read. Also, for what it's worth,
it brings us one baby step closer to handling spaces in store paths.
Also, I optimized handling of many transitive deps with read. Probably,
not very beneficial, but nice to enforce the pkg-per-line structure.
Doing so let me find much dubious code and fix it.
Two misc notes:
- `propagated-user-env-packages` also needed to be adjusted as
sometimes it is copied to/from the propagated input files.
- `local fd` should ensure that file descriptors aren't clobbered
during recursion.
I think it's ok to export things which aren't wrapped. The cc-wrapper
can be thought of as responsible for all of binutils and the c
compiler, only wrapping those binaries which are necessary to
interposition---as opposed to all binaries it thinks are relevaant.
Conversely, adding the setup hook to the unwrapped compilers would be
unforunate as hooks are ugly hacks and the compilers themselves take
a long time to rebuild. Better to wholely separate "pure packages" from
hacks.
Eventually we should avoid this "pre-wrapping" and just update those
files in nixpkgs. This mass-rebuild change is best done along with
those needed to reduce the disparity between native and cross (i.e.
making native the "identity cross").
We now (on cross) require per-target flag interposition by putting the
triple in the names of the relevant environment variables, e.g:
export NIX_arm_unknown_linux_gnu_CFLAGS_COMPILE=...
The wrapper also has a `infixSalt` attribute (and "_" prefixed and
suffixed variants) to assist downstream packages.
Note how that the dashes are replaced to keep the identifier valid.
Using names like this allows us to keep the settings for different
compilers seperate.
I think it might be even better to use names like `NIX_{BUILD,HOST}...`
using the platform's role rather than the platform itself, but this
would be more work as the previous stages' tools would have to be re-
wrapped to take on their new role. I therefore didn't do this for now,
but that route should be thoroughly explored in the future.
