[llvm-branch-commits] [clang] [Serialization] Code cleanups and polish 83233 (PR #83237)

[Utkarsh Saxena via llvm-branch-commits]

usx95 wrote:

> I tried to take a look at eigen and it looks like the declaration looks well and I had no clue how that happens. A reproducer may be necessary here to proceed. Thanks in advance.

I can reproduce using the following sources and invocations outlined in `run.sh`
https://github.com/usx95/llvm-project/commit/363d877bd317638b197f57c3591860e1688950d5

```sh
>  module-reproducer/run.sh

Building sensor_data.cc
Building tensor.cc
Building base.cc
In module 'sensor_data':
../../eigen/Eigen/src/Core/../plugins/CommonCwiseBinaryOps.inc:47:29: warning: inline function 'Eigen::operator*<float>' is not defined [-Wundefined-inline]
   47 | EIGEN_MAKE_SCALAR_BINARY_OP(operator*, product)
      |                             ^
../../eigen/Eigen/src/Geometry/AngleAxis.h:221:35: note: used here
  221 |   Vector3 sin_axis = sin(m_angle) * m_axis;
      |                                   ^
1 warning generated.
```
This warning is a new breakage and does not happed without this change (ignore the linker failure).

https://github.com/llvm/llvm-project/pull/83237