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feat(wpcarro/blog): Create short post about C#

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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>
This commit is contained in:
William Carroll 2022-06-21 12:49:02 -07:00 committed by clbot
parent 46ba96544a
commit ab1984c8ac
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7
users/wpcarro/website/blog/posts.nix
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@ -29,4 +29,11 @@
content = ./posts/auto-reboot-nixos.md;
draft = false;
}
{
key = "csharp-unused-variables";
title = "Unused Variables Broke Prod";
date = 1655840877;
content = ./posts/csharp-unused-variables.md;
draft = false;
}
]

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users/wpcarro/website/blog/posts/csharp-unused-variables.md Normal file
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@ -0,0 +1,40 @@
# Unused Variables Broke Prod
**Problem**: This morning we broke production because (believe it or not) an
unused variable went undetected.
**Solution**: Consume the variable in the relevant codepath.
**Further AI**: Treat unused variables as errors (which will block CI).
## Warning/Disclaimer
I am not a C# programmer. I know close to nothing about C#. But at `$WORK`, one
of our codebases is written in C#, so occasionally I interface with it.
## Treating Unused Variables as Errors
C# uses `.csproj` files to configure projects. The following changes to our
`.csproj` file WAI'd:
```diff
+ <!-- IDE0059: Remove unnecessary value assignment -->
+ <WarningsAsErrors>IDE0059</WarningsAsErrors>
+ <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
```
However, supporting this turned out to be a ~1h adventure... Why was this
unexpectedly difficult? As it turns out, there are the 3x promising compiler
warnings that I had to discover/try:
- `CS0219`: doesn't WAI (see "Note" here: https://docs.microsoft.com/en-us/dotnet/csharp/misc/cs0219)
- `CA1804`: silently unsupported (replaced by `IDE0059`)
- `IDE0059`: WAIs
Legend:
- `CS`: stands for C#
- `CA`: stands for Code Analysis (I *think* a Visual Studio concept)
- `IDE`: stands for IDE (I think *also* a Visual Studio concept)
For `CA` and `IDE` prefixed warnings, `EnforceCodeStyleInBuild` must also be
enabled.