clang-tidy warnings #584

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opened 2024-11-23 04:36:18 +00:00 by artemist · 1 comment

artemist commented

2024-11-23 04:36:18 +00:00

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Describe the bug

When upgrading to clang 18 a large number of new clang-tidy warnings appear. Many are nuisance warnings, but some may be hiding actual errors.

A few that seemed like they might be important:

lix/libstore/nar-accessor.cc
Line 148 in 66f6dbd
Path canon = path == "" ? "" : canonPath(path);
canonicalizes the path then completely ignores its canonicalized path
lix/libstore/build/local-derivation-goal.cc
Line 710 in 66f6dbd
Path logFile = openLogFile();
opens a log file then ignores the path
lix/nix/search.cc
Line 163 in 66f6dbd
auto name2 = hiliteMatches(name.name, nameMatches, ANSI_GREEN, "\e[0;2m");
highlights a name then doesn't do anything with it

A large number of places also dereference a std::optional then pass it to a function taking a std::optional. This is undefined behavior if the optional is empty. From tests in compiler explorer, clang and gcc will both silently mark the optional as having a value but leave the memory uninitialized.

Steps To Reproduce

Run clang-tidy, either with just tidy or nix build .#hydraJobs.tests.clang-tidy, after upgrading to nixpkgs 24.11 with clang 18. The warnings are also shown in a buildbot log.

Expected behavior

No warnings appear

`nix --version` output

N/A

## Describe the bug When upgrading to clang 18 a large number of new clang-tidy warnings appear. Many are nuisance warnings, but some may be hiding actual errors. A few that seemed like they might be important: * https://git.lix.systems/lix-project/lix/src/commit/66f6dbda32959dd5cf3a9aaba15af72d037ab7ff/lix/libstore/nar-accessor.cc#L148 canonicalizes the path then completely ignores its canonicalized path * https://git.lix.systems/lix-project/lix/src/commit/66f6dbda32959dd5cf3a9aaba15af72d037ab7ff/lix/libstore/build/local-derivation-goal.cc#L710 opens a log file then ignores the path * https://git.lix.systems/lix-project/lix/src/commit/66f6dbda32959dd5cf3a9aaba15af72d037ab7ff/lix/nix/search.cc#L163 highlights a name then doesn't do anything with it A large number of places also dereference a `std::optional` then pass it to a function taking a `std::optional`. This is undefined behavior if the optional is empty. From tests in compiler explorer, clang and gcc will both silently mark the optional as having a value but leave the memory uninitialized. ## Steps To Reproduce Run `clang-tidy`, either with `just tidy` or `nix build .#hydraJobs.tests.clang-tidy`, after upgrading to nixpkgs 24.11 with clang 18. The warnings are also shown in [a buildbot log](https://buildbot.lix.systems/api/v2/logs/596703/raw_inline). ## Expected behavior No warnings appear ## `nix --version` output N/A

artemist added the

bug

label 2024-11-23 04:36:18 +00:00

lix-bot commented

2024-12-06 01:14:11 +00:00

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This issue was mentioned on Gerrit on the following CLs:

commit message in cl/2282 ("tree-wide: fix a pile of lints")

This issue was mentioned on Gerrit on the following CLs: * commit message in [cl/2282](https://gerrit.lix.systems/c/lix/+/2282) ("tree-wide: fix a pile of lints")