ab1984c8ac
Inspired by Profpatsch's "Notes", here's a short post about a thing that happened today... Note: I'd like a way to convert `git log --format=%b` into blog posts (maybe). Maybe some commit metadata like `POST=true` Change-Id: I492c48c81891d9f64da8c8149d0d2bfa864ed731 Reviewed-on: https://cl.tvl.fyi/c/depot/+/5889 Tested-by: BuildkiteCI Reviewed-by: wpcarro <wpcarro@gmail.com> Autosubmit: wpcarro <wpcarro@gmail.com>
40 lines
1.4 KiB
Markdown
40 lines
1.4 KiB
Markdown
# Unused Variables Broke Prod
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**Problem**: This morning we broke production because (believe it or not) an
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unused variable went undetected.
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**Solution**: Consume the variable in the relevant codepath.
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**Further AI**: Treat unused variables as errors (which will block CI).
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## Warning/Disclaimer
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I am not a C# programmer. I know close to nothing about C#. But at `$WORK`, one
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of our codebases is written in C#, so occasionally I interface with it.
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## Treating Unused Variables as Errors
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C# uses `.csproj` files to configure projects. The following changes to our
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`.csproj` file WAI'd:
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```diff
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+ <!-- IDE0059: Remove unnecessary value assignment -->
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+ <WarningsAsErrors>IDE0059</WarningsAsErrors>
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+ <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
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```
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However, supporting this turned out to be a ~1h adventure... Why was this
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unexpectedly difficult? As it turns out, there are the 3x promising compiler
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warnings that I had to discover/try:
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- `CS0219`: doesn't WAI (see "Note" here: https://docs.microsoft.com/en-us/dotnet/csharp/misc/cs0219)
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- `CA1804`: silently unsupported (replaced by `IDE0059`)
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- `IDE0059`: WAIs
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Legend:
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- `CS`: stands for C#
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- `CA`: stands for Code Analysis (I *think* a Visual Studio concept)
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- `IDE`: stands for IDE (I think *also* a Visual Studio concept)
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For `CA` and `IDE` prefixed warnings, `EnforceCodeStyleInBuild` must also be
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enabled.
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