core dump on malformed remote repo build

[ethancedwards8]

Describe the bug

Accidentally mistyped the remote repo nix build command:

nix build git:github.com:nixos/nixpkgs

Steps To Reproduce

1. Run nix build git:github.com:nixos/nixpkgs#ripgrep
2. fail

Expected behavior

The package ripgrep should be built or downloaded from the cache

Metadata

nix-env (Nix) 2.32.4
nix-info -m:

• system: "x86_64-linux"
• host os: Linux 6.12.57, NixOS, 26.05 (Yarara), 26.05.20251225.3e2499d
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.32.4
• nixpkgs: /nix/store/0lc6kbmhkqk8vmgflpn2n1d1qb3vl2f5-source

Additional context

Core dump:

nix build git:github.com:nixos/nixpkgs#ripgrep


terminating due to unexpected unrecoverable internal error: Assertion 'path.empty() || path.front().empty()' failed in std::string nix::ParsedURL::renderAuthorityAndPath() const at ../url.cc:351
Nix crashed. This is a bug. Please report this at https://github.com/NixOS/nix/issues with the following information included:

std::terminate() called without exception
Stack trace:
 0# 0x0000557DC3BB1C81 in nix
 1# 0x00007F34544BF1AA in /nix/store/xm08aqdd7pxcdhm0ak6aqb1v7hw5q6ri-gcc-14.3.0-lib/lib/libstdc++.so.6
 2# std::unexpected() in /nix/store/xm08aqdd7pxcdhm0ak6aqb1v7hw5q6ri-gcc-14.3.0-lib/lib/libstdc++.so.6
 3# 0x00007F3455306BFF in /nix/store/d1j3flz8qr4n3lypwhk0v8ffvflfz914-nix-util-2.32.4/lib/libnixutil.so.2.32.4
 4# __wrap___assert_fail in /nix/store/d1j3flz8qr4n3lypwhk0v8ffvflfz914-nix-util-2.32.4/lib/libnixutil.so.2.32.4
 5# nix::ParsedURL::renderAuthorityAndPath[abi:cxx11]() const in /nix/store/d1j3flz8qr4n3lypwhk0v8ffvflfz914-nix-util-2.32.4/lib/libnixutil.so.2.32.4
 6# nix::ParsedURL::to_string[abi:cxx11]() const in /nix/store/d1j3flz8qr4n3lypwhk0v8ffvflfz914-nix-util-2.32.4/lib/libnixutil.so.2.32.4
 7# 0x00007F3454D94F60 in /nix/store/apbfhnn69hx6f8piiknhir3liv0xggld-nix-fetchers-2.32.4/lib/libnixfetchers.so.2.32.4
 8# 0x00007F3454D9494C in /nix/store/apbfhnn69hx6f8piiknhir3liv0xggld-nix-fetchers-2.32.4/lib/libnixfetchers.so.2.32.4
 9# nix::fetchers::Input::fromURL(nix::fetchers::Settings const&, nix::ParsedURL const&, bool) in /nix/store/apbfhnn69hx6f8piiknhir3liv0xggld-nix-fetchers-2.32.4/lib/libnixfetchers.so.2.32.4
10# 0x00007F3454855504 in /nix/store/drcd5p4hhgzpk3ygbgc1fxb1dzdkcpjk-nix-flake-2.32.4/lib/libnixflake.so.2.32.4
11# nix::parseURLFlakeRef(nix::fetchers::Settings const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, bool) in /nix/store/drcd5p4hhgzpk3ygbgc1fxb1dzdkcpjk-nix-flake-2.32.4/lib/libnixflake.so.2.32.4
12# nix::parseFlakeRefWithFragment(nix::fetchers::Settings const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::optional<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, bool, bool, bool) in /nix/store/drcd5p4hhgzpk3ygbgc1fxb1dzdkcpjk-nix-flake-2.32.4/lib/libnixflake.so.2.32.4
13# nix::SourceExprCommand::parseInstallables(nix::ref<nix::Store>, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >) in /nix/store/sf38q0nrgg5y52670n1v10b7z5gazasj-nix-cmd-2.32.4/lib/libnixcmd.so.2.32.4
14# nix::InstallablesCommand::run(nix::ref<nix::Store>, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&&) in /nix/store/sf38q0nrgg5y52670n1v10b7z5gazasj-nix-cmd-2.32.4/lib/libnixcmd.so.2.32.4
15# nix::RawInstallablesCommand::run(nix::ref<nix::Store>) in /nix/store/sf38q0nrgg5y52670n1v10b7z5gazasj-nix-cmd-2.32.4/lib/libnixcmd.so.2.32.4
16# nix::StoreCommand::run() in /nix/store/sf38q0nrgg5y52670n1v10b7z5gazasj-nix-cmd-2.32.4/lib/libnixcmd.so.2.32.4
17# 0x0000557DC3C21D03 in nix
18# nix::handleExceptions(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::function<void ()>) in /nix/store/9gb81q29df4q275c2pqdx8w52pvb67n6-nix-main-2.32.4/lib/libnixmain.so.2.32.4
19# 0x0000557DC3B8950B in nix
20# 0x00007F345402A4D8 in /nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6
21# __libc_start_main in /nix/store/xx7cm72qy2c0643cm1ipngd87aqwkcdp-glibc-2.40-66/lib/libc.so.6
22# 0x0000557DC3B8D9B5 in nix

Aborted                    (core dumped) nix -vL build git:github.com:nixos/nixpkgs#ripgrep

Checklist

• checked latest Nix manual (source)
• checked open bug issues and pull requests for possible duplicates

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Add 👍 to issues you find important.

[NaN-git]

@a-kenji found another example triggering the same assert, e.g. by using git+https:/codeberg.org/forgejo/forgejo as flake input URL.

In general this assert seems to be at the wrong place because ParsedURL::renderAuthorityAndPath() is called by ParsedURL::to_string(), having many callers.
When removing the assert the two examples don't crash nix, but rather more or less reasonable errors are reported.
The problem is that nix does many ad-hoc manipulations of URLs, so that it's not clear, when a URL is finalized and shall be valid.

[xokdvium]

The assert is correct, it is the invariant that must be maintained by a ParsedURL. It is fitGitUrl that produces an invalid ParsedURL that must be fixed.

[xokdvium]

See #14863.

[NaN-git]

The assert is correct, it is the invariant that must be maintained by a ParsedURL. It is fitGitUrl that produces an invalid ParsedURL that must be fixed.

I'm not stating that it's not correct, but it causes aborts in cases, where previous nix versions threw an error.

[xokdvium]

Yeah, I'm just saying that the assert is a good thing since it catches bugs loudly instead of just barfing on a bug.