<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/69444>69444</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang][Sema] Question: Why is `-Wshorten-64-to-32` disjoint from `-Wimplicit-int-conversion`?
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            enhancement,
            question,
            c++,
            clang:frontend
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          whisperity
      </td>
    </tr>
</table>

<pre>
    An interesting case was encountered where conversions from larger bit-width integers to smaller bit-width ones is *generally* reported by `-Wimplicit-int-conversion` (32 to 16, 16 to 8, 128 to 64, etc.) **except** for 64 to 32, which was given its own warning: `-Wshorten-64-to-32`.

See http://godbolt.org/z/6q4GMPsxs. Lines 19 (`uint64_t` -> `uint32_t`) and 35 (`int64_t` -> `int32_t`) are not warned about, unless _"Compiler 2"_'s warning is enabled.

Although `-Weverything` enables both of them at the same time (and neither is enabled by default, AFAIK), it is strange that 64->32 is such a specific dedicated case.

Unfortunately, all I could track down was commit 263a48b781f360fc75f4b95fb9abbb866209cb21 where this warning was introduced, and that is **ancient**, but history runs dry at that point.

> CC @dwblaikie, @rjmccall. Your names appeared in the relevant code path.

----

**What would be the cons against enabling `-Wshorten-64-to-32` under `-Wimplicit-int-conversion` implicitly?**
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJyEVN2O4zYPfRrlhnBgyz8TX-TCM_Plw6It0GJRDHo10A9ta1aWvBKdbPr0hexMpym6WCCIZZEmeQ7JI2I0g0M8svqR1c87sdDow_EymjhjMHTdSa-vx86BcYQBIxk3gBIR4SIioFN-WQ0aLiMGBOXdGUM03kXog5_AijBgAGkouxhN4xpowBCBPMRJWHtn9Q4jmAiMdwM6DMLaK-MdBJx9INQgr8CaPHsx02yNMpQZR9lHVtbkwPih5Cl80TD-BEWTzof1yA_p3FTpBUntGW9TKsY7_KZwpu0MvQ_QVMm15Mn1Mho1rogHc0YHhiL4i4OLCM64gZXdVlQcU5Eua6qMfFZy1uR7lj-zvNv-PyPCSDSzsmP8xPhp8Fp6S3sfBsZPfzJ-ar5W___l1_gt7uFnk8goUoUH1uSLcdRUr5QgZqz8H9zuSr7eJSjCaSjrm_9_uP_LOyA4TysK1CCkXyihXZzFGOGVcf7kp9mkDnHG-SvjD_Edc2oSOiEt6juInaXRL8O4EYJnDFcaE0dNfvOPIH3qdA804gSC0hOimBDITJiqTzgcGhox_CNP6r3GXix2LbM7dZ9-YrxNZ0PJL1IQbkCgURA0VUJd8tWwqBEExBmV6Y0CjdookcYpjfJd_b-73gdanCBMk_cEwlr4BMovVgMFob6A3lofQflpMgS8KUV1kA-Hoi-bvFcPdV_Jtu5lK6SUh6bheaskL24rQqP5YDGFMY6C14tCveZzegOwbQHjnXDKoLvNZnKRC8FoIvlwhbC4CDpcNx4FweyNoztIqflPT8CqXF-kFeaLwRSFVXl4m5QS1u7hD78EcGLCCGKeUaSNNm7tTECLZ-EIlNcIs6DxLnqWZdldtrXMl1TKZSVN4hpGJUkQgzAu0tbRhP97awOL0xh-uOrvJntl5WnLvNPHUrdlK3Z4LJr2oeH1gde78VjWuq7rqi0Etn3Vl7I6VFq2Vdn2vOyx3pkjz3lZ5MWhyKuyqvf8QRW84D32WrZF3rMqx0kYu7f2PKWd3ZkYFzw2bVVVOysk2rgqKefoRuEUTmvfkoYwzr8uST-9-_tCMf64_t7frVjFpA_eETqdDPXzLhxTvkwuQ2RVbk2k-FEBGbKrfG8f18-sfvyMk2D1M_z2nrDs4GW8rhP1Pb61iW9pcjbV_gHvrDztlmCPScvih5gZGhe5V35i_JQKvD2yOfg3VMT4aeUrJplLlP0VAAD___mADfk">