Input::isRelative(): Fix assertion failure

[edolstra]

Motivation

This happens if a lockfile contains an input with an unknown type field.

Spotted in a Sentry crash report.

SIGABRT / SI_TKILL / 0x0: Fatal Error: SIGABRT / SI_TKILL / 0x0
  libc.so.6           0x7dd077c9caac __pthread_kill_implementation (pthread_kill.c:44)
  libc.so.6           0x7dd077c4190d __GI_raise (raise.c:26)
  libc.so.6           0x7dd077c28941 __GI_abort (abort.c:79)
  libstdc++.so.6      0x7dd0780adc3d null
  libnixfetchers.so.2.34.60x7dd07856ebf3 __wrap___assert_fail (wrap-assert-fail.cc:16)
  libnixfetchers.so.2.34.60x7dd07852c4db nix::fetchers::Input::isRelative[abi:cxx11] (fetchers.cc:177)
  libnixfetchers.so.2.34.60x7dd07852c4db nix::fetchers::Input::isRelative[abi:cxx11] (fetchers.cc:175)
  libnixflake.so.2.34.60x7dd078f1be19 nix::flake::LockedNode::LockedNode (lockfile.cc:78)
  libnixflake.so.2.34.60x7dd078f1e41c std::_Construct<T> (stl_construct.h:119)
  libnixflake.so.2.34.60x7dd078f1e41c std::allocator_traits<T>::construct<T> (alloc_traits.h:706)
  libnixflake.so.2.34.60x7dd078f1e41c std::_Sp_counted_ptr_inplace<T>::_Sp_counted_ptr_inplace<T> (shared_ptr_base.h:607)
  libnixflake.so.2.34.60x7dd078f1e41c std::__shared_count<T>::__shared_count<T> (shared_ptr_base.h:969)
  libnixflake.so.2.34.60x7dd078f1e41c std::__shared_ptr<T>::__shared_ptr<T> (shared_ptr_base.h:1713)
  libnixflake.so.2.34.60x7dd078f1e41c std::shared_ptr<T>::shared_ptr<T> (shared_ptr.h:463)
  libnixflake.so.2.34.60x7dd078f1e41c std::make_shared<T> (shared_ptr.h:1008)
  libnixflake.so.2.34.60x7dd078f1e41c nix::make_ref<T> (ref.hh:164)
  libnixflake.so.2.34.60x7dd078f1e41c _ZZN3nix5flake8LockFileC4ERKNS_8fetchers8SettingsESt17basic_string_viewIcSt11char_traitsIcEES9_ENHUlRKT_RNS0_4NodeERKN8nlohmann16json_abi_v3_12_010basic_jsonISt3mapSt6vectorNSt7__cxx1112basic_stringIcS8_SaIcEEEblmdSaNSG_14adl_serializerESJ_IhSaIhEEvEEE_... (lockfile.cc:171)
  libnixflake.so.2.34.60x7dd078f1f983 nix::flake::LockFile::LockFile (lockfile.cc:182)
  libnixflake.so.2.34.60x7dd078ef7775 nix::flake::readLockFile (flake.cc:428)
  libnixflake.so.2.34.60x7dd078f001c6 nix::flake::lockFlake (flake.cc:449)
  libnixflake.so.2.34.60x7dd078f0350c nix::flake::lockFlake (flake.cc:956)
  nix                 0x5fabcc9dd358 nix::FlakeCommand::lockFlake (flake.cc:61)
  nix                 0x5fabcc9ddd99 .LTHUNK42.lto_priv.0 (flake.cc:176)
  libnixcmd.so.2.34.6 0x7dd07897c2fe nix::StoreCommand::run (command.cc:110)
  libnixcmd.so.2.34.6 0x7dd07897c457 {virtual override thunk}
  nix                 0x5fabcca145f5 nix::mainWrapped (main.cc:638)
  libnixutil.so.2.34.60x7dd079041635 std::function<T>::operator() (std_function.h:591)
  libnixutil.so.2.34.60x7dd079041635 nix::fun<T>::operator()<T> (fun.hh:78)
  libnixutil.so.2.34.60x7dd079041635 nix::handleExceptions (error.cc:489)
  nix                 0x5fabcc974d22 main (main.cc:661)
  libc.so.6           0x7dd077c2a4d7 __libc_start_call_main (libc_start_call_main.h:58)
  libc.so.6           0x7dd077c2a59a __libc_start_main_alias_2 (libc-start.c:360)
  nix                 0x5fabcc97a1f4 _start

Context

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Improved error handling for inputs without schemes, providing clearer error messages instead of unexpected failures
  • Enhanced robustness when processing unsupported input types, ensuring more graceful degradation

[github-actions]

🚀 Deployed on https://6a15d49e22cb407a0562609f--determinate-nix.netlify.app

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 2c0ded6f-b712-4ba8-bef2-0adf684241f8

📥 Commits

Reviewing files that changed from the base of the PR and between b93743b and bbbac4d.

📒 Files selected for processing (1)

• src/libfetchers/fetchers.cc

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📝 Walkthrough

Walkthrough

Input methods that depend on a scheme now gracefully handle null schemes. Input::isRelative() returns std::nullopt for unsupported input types, while Input::clone() and Input::putFile() throw Error with clear messages, and Input::getSourcePath() returns std::nullopt instead of asserting.

Changes

Null scheme error handling

Layer / File(s)	Summary
Optional scheme handling in Input::isRelative() src/libfetchers/fetchers.cc	isRelative() returns std::nullopt when the input has no scheme, instead of asserting.
Error handling in clone, getSourcePath, and putFile src/libfetchers/fetchers.cc	clone() and putFile() throw Error with descriptive messages for unsupported inputs; getSourcePath() returns std::nullopt instead of asserting on null scheme.

🎯 2 (Simple) | ⏱️ ~8 minutes

🐰 A scheme once asserted with might,
Now handles null with gentle grace,
Optional returns and errors bright,
Put unsupported inputs in their place!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly describes the main change: fixing an assertion failure in Input::isRelative(), which aligns with the PR objectives of preventing crashes from assertion failures when encountering inputs with unknown types.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix-isRelative-crash

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