chore: gitignore ephemeral files that clangd uses
This PR tells git to ignore ephemeral files that are created when
developers use clangd.
clangd needs a `compile_commands.json` file at the root of the repo (or
in a `build/` directory) to tell it how to compile each file. CMake can
generate this file with something like the following:
```console
$ cmake -Scmake -B.build \
-DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
-Dprotobuf_BUILD_TESTS=OFF
$ ln -sf .build/compile_commands.json .
```
Then clangd will compile and index files into the `.cache` directory.
diff --git a/.gitignore b/.gitignore
index 1040236..4fe3edd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -222,3 +222,7 @@
# BenchmarkDotNet
BenchmarkDotNet.Artifacts/
+
+# Clangd uses these common ephemeral files
+.cache
+compile_commands.json
