<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/113824>113824</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            What causes clang to produce weak external symbols for template parameter objects?
        </td>
    </tr>

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

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

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

<pre>
    I'm not 100% confident that this is clang, it might be the linkers doing, but I'm trying to figure out what the criteria is for when a symbol with the form "weak external template parameter object" is produced and if that criteria has changed over releases.

Background is that I'm attempting to use NTTPs somewhat extensively in a project (WebKit) that has a post build script that looks for symbols in the linked output (via `nm -m`) that are "weak external" (https://github.com/WebKit/WebKit/blob/main/Tools/Scripts/check-for-weak-vtables-and-externals#L80) and errors if it finds any. (I don't know the history behind the script.) 

I have gotten a report from the WebKit team that on older versions of clang (I am working on getting better details from them, but so far I have "Debug Sonoma and Ventura Xcode"), this script is producing an error.

I haven't been able to figure out what exactly provokes the generation of this type of symbol and was hoping there might be something I am just overlooking. My presumption is that it has to do with some ODR, but I can't work out any details.

--

In case it is helpful, the specific symbols it generates weak external for are:

__ZTAXtlN7WebCore3CSS5RangeELd0000000000000000ELd7ff0000000000000EEE 
(run through c++filt: "template parameter object for WebCore::CSS::Range{0x0p+0, inf}")
__ZTAXtlN7WebCore3CSS5RangeELdfff0000000000000ELd7ff0000000000000EEE 
(run through c++filt: "template parameter object for WebCore::CSS::Range{-inf, inf}")

and the commit it triggers on is https://github.com/WebKit/WebKit/commit/4692eacc698b91686bf635d0b4e3030853edfd97
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzEVU2P2zgS_TX0pWBDpizJPvjQXwaCzWYX6cYm2EtAiUWJMUUKZMmO__2AouxO52Mwc5o-qNVq6dV7j_WqRAi6tYh7Vtyz4nEhRuqc359RW90uaicv-3eMVz1YR7DOMsYLaJxVWqIloE7Eiw6gAzRG2JbxB9AEvW47ghqBOgSj7RF9AOl0eqEeCRIq-Yu2LZADpdvRI7iR4JxQERqvCb0WEV05D-cOLQgIl752Bs6auuk15XwPjPMziiPgN0JvhQHCfjCCEAbhRY-EHlz9FRtinEfAwTs5NihBWAlaJS23ip0I0HTCtijBndCDR4MiYFix7JFld-l6L5pj690YEUJCSLoExfI0axsDwoeXl_8GCK7HSV6kaYM-obmAjqIG7yI5YHz7Cet_aWJ8lxAjFQGDCwT1qI2E0Hg9zOYb547JnORKiGg302X0cxgn1JMWwMrM9rDsWZnd4IXHn8yLFjG-7YiGwPI7xg-MH1pN3VivGtczfrhyfL2pjasZP_RCW8YPL86ZwPjheeIa75oOm-NSOb-MpZYnErXBsBRWLq9lA-P5--1ELR4Keu98iGejCZS2MoCwl1Vk9g6ks4xXBEfrzpPgTgdy_gI1dtrK6VEyahXxvj-1d9CJE0LriKZ-8jg4T6C866fPkiQgFH2yyFlwRqKHE_qgnQ3gVGr3xEX0cHb-GE_bWWiRpoOvkWLTSSShTbjB99cEBAdKeJjZMM4fsR5beHbW9WIy4H9oafQCPjdOIuOc8V38eArc3AS3Ro4VhU2erX5Wm8yqMQquDf4qcfhNNGQuEe_kjhgmL1q06AXpaIFKlekyYPxjjmEkehYBOjdM7d6hx9f8x4anLv5jsunrGGjKU-xbbdsV_DsWxDDGtDh7i5FOfU8OpEtJj0jwn8ePtwECjUiqoveTDGEvV7vfWLBcvjHEQiMCxhI6QIdmUKNJviKEARutdPMaJ7p6gAHeTpiYOuExBuQ7-C9f_v9y95nMh-oT1g_OY_7w_Fx8jKPk6b3Mfvh5ei8rpd4-enq6tivf-jHG2bux7aBh_J7xe6UNsfwudsxvZ9zEba4f-eV3D8_P6WZiwqr77Fs2MH6fTRPbKlY9zh32F1SoHyn_YyqWkfovFaSrmEdB4_peT21FXrdtXEep2_7WjEsojB825Y6jaJpyt61363Jb1qrMC5nVG8yzPNsWOUold9VC7nO5y3digft1lWfZptoWxaLbN-sSC86FUpXYbVS9brJyKzNVboq8VsV2ofc845t1xqt1WWRFsSrX611VN0LIspKbbM02GfZCm5Uxp37lfLvQIYy4X6_zLd8sjKjRhGmtcz6vZh43vN_HD5b12Aa2yYwOFF4hSJPB_adpFYox4LzVYw7nfflDBq4xiSf123MMLD8sRm_2f2J2pDD_Ws67kPHDJCluj1nVac__CAAA__9Wd9u0">