cc-wrapper: expose a single, consistent libcxx #282221
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ghost
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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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8.has: package (new)
| 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
| @@ -55,6 +55,26 @@ | |||
| , 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
| @@ -112,6 +112,13 @@ let | |||
| gccForLibs_solib = getLib gccForLibs | |||
| + optionalString (targetPlatform != hostPlatform) "/${targetPlatform.config}"; | |||
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| libcxx = | |||
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Can't you just move this into the default expression of libcxx in the args set? Or does something explicitly pass libcxx = null?
| @@ -451,7 +449,7 @@ stdenv.mkDerivation { | |||
| '' | |||
| + optionalString useGccForLibs '' | |||
| echo "-L${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" >> $out/nix-support/cc-ldflags
| @@ -11752,7 +11752,7 @@ with pkgs; | |||
| boost = boost179; | |||
| libclang = llvmPackages_15.libclang; | |||
| clang = | |||
| if stdenv.cc.libcxx != null | |||
| if stdenv.cc.isClang | |||
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stdenv.cc.libcxx.pname should be checked. Not all clang based stdenvs use libcxx which would be the case in the else condition then…
Description of changes
This PR attempts to expose a single consistent
stdenv.cc.passthru.libcxxattribute from which downstream packages (like CUDA) can determine whatever they need to determine about the C++ standard library in use.Best reviewed one commit at a time; some of the commits are straightforward search-and-replace.
The following PR (which must go to
staging) may be needed in order to ensure that${lib.getLib stdenv.cc.cc}/libcontains the C++ libraries regardless of which compiler is being used: