[0xull]

related to #61

adds cargo::rerun-if-changed=src to cpp-overload-test/build.rs.

once a build script prints any rerun-if line, cargo stops rescanning the package (cargo docs). so editing a cpp! block never reran the script, and the build failed with "This cpp! macro is not found in the library's rust-cpp metadata" until build.rs was touched.

after touch cpp-overload-test/src/stdcpp/forward_list.rs and cargo build -v:

before:

       Dirty cpp-overload-test v0.0.0 (...): the file `cpp-overload-test/src/stdcpp/forward_list.rs` has changed (...)

after:

       Dirty cpp-overload-test v0.0.0 (...): the file `cpp-overload-test/src` has changed (...)
     Running `.../target/debug/build/cpp-overload-test/<hash>/out/build_script_build`

[0xull]

hi @teor2345

i was thinking of these edits to the docs, since the build.rs change somewhat affects this section:

 ## Testing Quirks

-Sometimes the C++ code extracted by `cpp_build` will become outdated, and you will get errors like:
+`cpp-overload-test/build.rs` tells Cargo to rerun `cpp_build` whenever a file in
+`cpp-overload-test/src` changes, so new or changed `cpp!` blocks are picked up on the next build.
+
+If you still get errors like:

```text
 error: This cpp! macro is not found in the library's rust-cpp metadata.
        NOTE: Only cpp! macros found directly in the program source will be parsed -
        NOTE: They cannot be generated by macro expansion.
 ...
 error: cannot find macro `__cpp_closure_impl` in this scope
```

-To fix these errors, run `cargo clean` then rebuild.
-If the errors still happen after a clean, check your Rust and C++ code is compiling correctly.
+check that the `cpp!` block is written directly in `cpp-overload-test/src`, and isn't generated by
+another macro, or used in an example or binary (`cpp_build` only runs for `lib.rs`).
+If the errors still happen, run `cargo clean` then rebuild, and check your Rust and C++ code is
+compiling correctly.

what do you think about it?

[teor2345]

hi @teor2345

i was thinking of these edits to the docs, since the build.rs change somewhat affects this section:

Go for it, it is easier for me to review doc changes in the GitHub changes view than as a diff in a comment.

[teor2345]

This looks good but I'd like to add a CI test if possible.

[teor2345]

Is it possible to add a CI test for this change?
This will make sure:

• the change does what it is documented to do
• it keeps on doing that when we make future changes to the build script, or upgrade cpp or cpp_build
• it works in the CI environment

For example, you could add a CI test script that:

1. Builds some cpp! code and checks its output
2. Adds a new cpp! Invocation and/or changes the C++ code inside an existing one
3. Rebuilds and checks the build is successful and the output has changed

You could create a replacement file (which isn't in the build by default) and use cp to copy it over the original file in step 2.