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nix develop: Add --redirect flag to redirect dependencies

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This is primarily useful if you're hacking simultaneously on a package
and one of its dependencies. E.g. if you're hacking on Hydra and Nix,
you would start a dev shell for Nix, and then a dev shell for Hydra as
follows:

  $ nix develop \
    --redirect .#hydraJobs.build.x86_64-linux.nix ~/Dev/nix/outputs/out \
    --redirect .#hydraJobs.build.x86_64-linux.nix.dev ~/Dev/nix/outputs/dev

(This assumes hydraJobs.build.x86_64-linux has a passthru.nix
attribute. You can also use a store path.)

This causes all references in the environment to those store paths to
be rewritten to ~/Dev/nix/outputs/{out,dev}. Note: unfortunately, you
may need to set LD_LIBRARY_PATH=~/Dev/nix/outputs/out/lib because
Nixpkgs' ld-wrapper only adds -rpath entries for -L flags that point
to the Nix store.
This commit is contained in:
Eelco Dolstra 2020-10-18 21:06:36 +02:00
parent 21830cb044
commit f9438fb64a
1 changed files with 50 additions and 3 deletions
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53
src/nix/develop.cc
View file

@ -185,7 +185,22 @@ struct Common : InstallableCommand, MixProfile
"UID",
};
std::vector<std::pair<std::string, std::string>> redirects;
Common()
{
addFlag({
.longName = "redirect",
.description = "redirect a store path to a mutable location",
.labels = {"installable", "outputs-dir"},
.handler = {[&](std::string installable, std::string outputsDir) {
redirects.push_back({installable, outputsDir});
}}
});
}
std::string makeRcScript(
ref<Store> store,
const BuildEnvironment & buildEnvironment,
const Path & outputsDir = absPath(".") + "/outputs")
{
@ -217,6 +232,8 @@ struct Common : InstallableCommand, MixProfile
out << "eval \"$shellHook\"\n";
auto script = out.str();
/* Substitute occurrences of output paths. */
auto outputs = buildEnvironment.env.find("outputs");
assert(outputs != buildEnvironment.env.end());
@ -230,7 +247,33 @@ struct Common : InstallableCommand, MixProfile
rewrites.insert({from->second.quoted, outputsDir + "/" + outputName});
}
return rewriteStrings(out.str(), rewrites);
/* Substitute redirects. */
for (auto & [installableS, dir] : redirects) {
dir = absPath(dir);
auto installable = parseInstallable(store, installableS);
auto buildable = installable->toBuildable();
auto doRedirect = [&](const StorePath & path)
{
auto from = store->printStorePath(path);
if (script.find(from) == std::string::npos)
warn("'%s' (path '%s') is not used by this build environment", installable->what(), from);
else {
printInfo("redirecting '%s' to '%s'", from, dir);
rewrites.insert({from, dir});
}
};
std::visit(overloaded {
[&](const BuildableOpaque & bo) {
doRedirect(bo.path);
},
[&](const BuildableFromDrv & bfd) {
for (auto & [outputName, path] : bfd.outputs)
if (path) doRedirect(*path);
},
}, buildable);
}
return rewriteStrings(script, rewrites);
}
Strings getDefaultFlakeAttrPaths() override
@ -348,6 +391,10 @@ struct CmdDevelop : Common, MixEnvironment
"To use a build environment previously recorded in a profile:",
"nix develop /tmp/my-shell"
},
Example{
"To replace all occurences of a store path with a writable directory:",
"nix develop --redirect nixpkgs#glibc.dev ~/my-glibc/outputs/dev"
},
};
}
@ -357,7 +404,7 @@ struct CmdDevelop : Common, MixEnvironment
auto [rcFileFd, rcFilePath] = createTempFile("nix-shell");
auto script = makeRcScript(buildEnvironment);
auto script = makeRcScript(store, buildEnvironment);
if (verbosity >= lvlDebug)
script += "set -x\n";
@ -449,7 +496,7 @@ struct CmdPrintDevEnv : Common
stopProgressBar();
std::cout << makeRcScript(buildEnvironment);
std::cout << makeRcScript(store, buildEnvironment);
}
};