cc-wrapper: expose a single, consistent libcxx#282221
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January 19, 2024 21:47
This hopefully-obviously-correct commit will allow to change libcxx (see next commit) since it is no longer referenced.
Because the previous commit eliminated all uses of `libcxx` within `cc-wrapper/default.nix` (except for the binding of `libcxx_args`), this commit -- which adds a new binding for `libcxx` -- should have absolutely no effect.
The previous commit sets `libcxx` equal to `gccForLibs` whenever `useGccForLibs` is `true`. This allows us to eliminate all uses of `gccForLibs`.
If `useGccForLibs==true` then `libcxx` is equal to `gccForLibs`, so we can replace `gccForLibs` with `libcxx` inside of any `if useGccForLibs` block.
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| libcxx = | ||
| if libcxx_args != null | ||
| then libcxx_args | ||
| else if useGccForLibs | ||
| then lib.getLib gccForLibs | ||
| else null; |
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libcxx has a connotation with the specific implementation; I think @rrbutani's naming was good: cxxStdlib
| , includeFortifyHeaders ? null | ||
| }: | ||
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| let libcxx_args = libcxx; in |
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Instead of the sequence of let-expressions one could also add @args after the lambda's formal parameters, and then define libcxx = if args.libcxx != null then args.libcxx else .... Can't say which one is less "wacky". I've seen (and committed) both in nixpkgs
| gccForLibs_solib = getLib gccForLibs | ||
| + optionalString (targetPlatform != hostPlatform) "/${targetPlatform.config}"; | ||
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| libcxx = |
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Can't you just move this into the default expression of libcxx in the args set? Or does something explicitly pass libcxx = null?
| + optionalString useGccForLibs '' | ||
| echo "-L${gccForLibs}/lib/gcc/${targetPlatform.config}/${gccForLibs.version}" >> $out/nix-support/cc-ldflags | ||
| echo "-L${gccForLibs_solib}/lib" >> $out/nix-support/cc-ldflags | ||
| echo "-L${libcxx_solib}/lib" >> $out/nix-support/cc-ldflags |
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This needs to be the following, right?
echo "-L${libcxx_solib}${optionalString (targetPlatform != hostPlatform) "/${targetPlatform.config}"}/lib" >> $out/nix-support/cc-ldflags
| libclang = llvmPackages_15.libclang; | ||
| clang = | ||
| if stdenv.cc.libcxx != null | ||
| if stdenv.cc.isClang |
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stdenv.cc.libcxx.pname should be checked. Not all clang based stdenvs use libcxx which would be the case in the else condition then…
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Description of changes
This PR attempts to expose a single consistent
stdenv.cc.passthru.libcxxattribute from which downstream packages (like CUDA) can determine whatever they need to determine about the C++ standard library in use.Best reviewed one commit at a time; some of the commits are straightforward search-and-replace.
The following PR (which must go to
staging) may be needed in order to ensure that${lib.getLib stdenv.cc.cc}/libcontains the C++ libraries regardless of which compiler is being used: