<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/85008>85008</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang] error in backend: cannot guarantee tail call due to mismatched varargs
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

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

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

<pre>
    LLVM IR (`foo.ll`)
```
define void @a(...)  {
entry:
  musttail call void @b(...)
  ret void
}

define void @b(...) {
entry:
 ret void
}
```

Command to run:
`clang foo.ll`

Console output:
```
warning: overriding the module target triple with x86_64-pc-windows-msvc19.30.30706 [-Woverride-module]
cannot guarantee tail call due to mismatched varargs
  musttail call void @b(...)
fatal error: error in backend: Broken module found, compilation aborted!
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: C:\\dev\\llvm-project\\build\\bin\\clang.exe -cc1 -triple x86_64-pc-windows-msvc19.30.30706 -emit-obj -mrelax-all -mincremental-linker-compatible -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name test.ll -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -fdebug-compilation-dir=C:\\dev\\sylladexian\\compiler -fcoverage-compilation-dir=C:\\dev\\sylladexian\\compiler -resource-dir C:\\dev\\llvm-project\\build\\lib\\clang\\19 -ferror-limit 19 -fmessage-length=205 -fno-use-cxa-atexit -fms-extensions -fms-compatibility -fms-compatibility-version=19.30.30706 -fskip-odr-check-in-gmf -fdelayed-template-parsing -fcolor-diagnostics -faddrsig -o 
C:\\Users\\...\\AppData\\Local\\Temp\\test-3226d9.o -x ir ../test.ll
1.      Optimizer
clang: error: clang frontend command failed with exit code 70 (use -v to see invocation)
clang version 19.0.0git (https://github.com/llvm/llvm-project.git ead0a9777f8ccb5c26d50d96bade6cd5b47f496b)
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\dev\llvm-project\build\bin
clang: note: diagnostic msg: Error generating preprocessed source(s) - no preprocessable inputs.
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJykVltv2zoS_jXyy2AEWfL1wQ9J3AAFsthi2919PBiRI5kNRQrkyHHOrz-gJOdSpDhoTxBYI4rDuX3zDSlG0zrmQ7a-zdbHBQ1y8uEggbm3JLyovX4-PDz871_w-T-QlbtsUzTe59ZmmyIr91lxzIqbJE__46vmxjiGszcaslVBWbnL8zwr9wDZ9nbaw07Cc1bdTG8A3RBFyFhQZO2Lav2iet0XWMavs-HtcRY-Mvyq_VO7PzvufUDT753vOnIaxEMY3MsZ2aZQllwLr3l5p-Sitwx-kH6Qt0pvDTxRcMa1WXUD_swhGG1cC3Ji6LweLINQaFlAguktw5ORE1x2mz82K-wVPhmn_VPELp7Vcp9XRV4V22ID2foW_z-fxzidlK3nEBU55wXagQI54WTimn09cAqyM7EjUSfWcKZAoY2_VqyGhCxwCD6kwEYBjIOa1CM7ndZug39kdw2y8YPTWXkHyne9sSTGO6DaB2Gdlcvp1C8Pn26-foI41J0RIKiHFgL3Pkjy-STSx5Tl8j4r71sjp6HOle-y8t7a8_WBffDfWUlW3psYB45ZeQ-ptMYpO2geM68CxdPorARSnPzqA_fBK46RNUQ_hGk5aVKMXhkS1gkcEFUwveSTy1-F1CPooetf6l_kMP59Cb4N1AGFdujYSfId7tK29V22vtN8noR3Xo8r9WCsnkXjJmHEYc4XBlRqCTjD5e-RgtwZQV9_B-wCW7pgKix2xqnAyS-yaI175ICpNiSmtgyYQtImACGgNpFqy9gETuYtU0CKgjU3PjDORQfsyDhsjGV01DEIR8lHW4GtV2PNE1TZQm8UYG8UWj6zhRKwawJ1jL03Tjhk1dF5x4BNR3JCDsF5wKbpUXmXaiZZdfQOsHEeQ8KWcS2mvYCd8i5KGJT4gGQNRY6AzeBShlBSJDGrjiXg1Hmo-iHlETcrQBkcjwstOw7Jy0ZzPbT4BreoTXLwg1LGZ2tJ88XQtWqjFgfARqVupZb_8UmBJ3gm5V_GkzX1GzxN4nIP2IwtjNakzhsXOo4xuWvZtXJKCSvWU76HyKguhCR8MZK2RuSLsIvGuzi9X6FkrJHnD5bwzCFtz6rjO7A28dH06HVAdWL1iMZh2zVjFSw9s0bhbpxe2FOIiUlTZq0PqA21zkcxKrlAWodoWkAPM1m_JOq_kUOcxERpo3DT90cSml4evCI7id-46ycpgRmrstzofe4BL2ACJEK8n1E-WVnOvf_vXkxn_uQwE_KY7CtRJmEeK8E7Sa2j5vnTkLGspyEwJld5zbAt0ngeIgOeExNGZjDuPLfUCylPZ86JheU-L_KiNZJ0f40786TFpAvab7fbZqdUvVblRq8Lvd_UpHmj9LpebZvVflO_mP82dlMK7mNSmnedApOGkQbS3t5Hc5k-fXZRyFrWRxPecOUE7B9QfYV04sf3KXZeOD1f8QBdHL98GqfU2NgkCTofcv4upksFgvNvvifSAOP6QWL-w5Rf6EOl99WeFnxYbpdFua_KqlqcDlTu1oVW6812Wa2barktih2vaK94s9luqVqYQ1mUq6JaVsWy3C6rfKu0VppZp6wvd022KrgjY_MUfO5DuxhH2mG3LordwlLNNo63u7Kcwi_LdNELhzFZ9dDGbFVYEyW-niBG7HglnAng-OHw_p0bxGII9vD7Q3oM6q8AAAD__x-7bn0">