<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=http://email.email.llvm.org/c/eJylVFFvmzAQ_jXwcgIBxiQ88JAljVRpb93Ux8ixDXgzNrNNk_37HSTttC6dWg3ZYJ_Pd999d8fRip_NAxtGLYFbISOyibJdlG2iKruOy7YgynA9CQkR2foglE37iNwBQFTscUCrztBaB1wz00XFFryU0Icw-tnmouMD49_tk3SttqeU2wFlP3BWdb2q6pLiMl-t1sWK_nbawuHw8GW3PdzfbQ-U1ocDAtjhgPxFaXSsGxgM0nvWIcCi-OuO8qhfFC9XpPbyg_eNDa9sGKHam2zdmyfLWVDW_IPPC1OQkzRLM7AGPisznefFeV0lVfmsWF4VQ5ZySJB6DJ7nOSSjFMwEhcJHpjW-5Tk4BknbjsmAudSo2DIfbgK4O4-SBylAKNYZ69GOfwvs7BnPKM4aJ5yYMwqTjMs3iYKIfkoeX8hNruT6iO5u-tjwMDH9ATTknWg-jOS-vRI-GSEdRmOQdKd4ACxbTKrpktEqE2Dh2IOw8hIztwYbYIBgIfQSPBKsWnWpAw_KLNKNMfIM-7lBcGuWljn1ivcwTm60XoIKIGSrDFpFTK9DQtHsAD_5jJjsY9EQUZOaxWwKvXXNOFiXk3hyuvmz_ToV-ul47Tutn54_yejsNywG3CrvJ2Sm2FOSkyLuG8JWJVutqahWfE0EP2ZHWmW8plSuW1pVsWZHJKFBjrE1jDzBYmJuE7qL_x-BaoqsKLIcH1rSvEo5K2qxbnPKSFmveR6VmRyY0ulsJ7Wui12zmDxOncdDrXzwvw-Z96ozUi6AEWFQQcvmK_7aJHM3knGroi7ZEXMa8ncWSbyE1Swx_QKfSqLp>53132</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Unclear for which purpose __STDC_IEC_559__ is defined to 1 under non-strict floating-point models
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          pmor13
      </td>
    </tr>
</table>

<pre>
    Sample code:
```
#include <stdio.h>   // fix for clang, see https://stackoverflow.com/q/69976945/1778275
#if __STDC_IEC_559__ == 1
#pragma message "__STDC_IEC_559__ is 1"
#else
#pragma message "__STDC_IEC_559__ is not 1"
#endif
```
Invocation:
```
# clang 13.0.0 on Linux on x86-64
$ clang t0.c -std=c11 -pedantic -Wall -Wextra -ffp-model=fast
```
Expected diagnostics:
```
t0.c:5:9: warning: __STDC_IEC_559__ is not 1 [-W#pragma-messages]
```
Actual diagnostics:
```
t0.c:3:9: warning: __STDC_IEC_559__ is 1 [-W#pragma-messages]
```
If clang under non-strict floating-point models does not conform to the specifications in the Annex F, then for which purpose it defines `__STDC_IEC_559__` to `1`?
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJyVU11vmzAU_TXwcgUCG0h44CFLGqnS3rqpj5FjG_BmbGabJvv3u5C01bp0aiM7-OP63HOPfY5W_G4e2DBqCdwKGdFNlO2ibBNV2bVdpoQqw_UkJER064NQNu0jegcAEdljg1adobUOuGami8gWvJTQhzD6GXOJ8YHxn_ZJulbbU8rtgGu_sFd1varqosRhvlqtyap8TdrC4fDwbbc93N9tD2VZHw5IYIcN8peg0bFuYDBI71mHBAn554zyGE_IyxGpvfzkeWPDGwwjVHtTrXvzZDkLypr_6HlRCnKaZmkG1sBXZabzPDivq6QqngOLa2DIUg4JSo_F8zyHZJSCmaBw8ZFpjf_yHByDpG3HZMC71BjYMh9uErg7j5IHKUAo1hnrEce_R3bOjHsl9ho7nJgzCi8Zh-8KBVH5JXl8ETe5iuujcnczx4aHielPsKEfZPNpJvftVfDJCOmwGoOiO8UD4LPFSzVdMlplAiwaexBWXmrm1qABBggWQi_Bo8CqVZd34EGZZXVjjDzDfjYITs1imVOveA_j5EbrJagAQrbKICpyelsSLs0J8JPPjOk-Fg0VNa1ZHFTQsvmONpXM3QC-pc4lk5gh8w8WHE9ON38bu1Ohn45XR2v99PxJRmd_4DPDqfJ-Qs3JvqQ5JXHfrOp13tJWCIHOz2QlSrbOOCErUlZFJotYsyNma_D20HRGnmCBmA1Y7mLVkIyQLMdfWZR5lXJGarFu85LRol7zPEKMgSmdzjxS67rYNQul49R53NTKB_-6ybxXnZFySYf4bAq9dc04WJfTeMncLMz_ABrpjUQ">