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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Unconvertable type leads to invalid WebAssembly"
href="https://bugs.llvm.org/show_bug.cgi?id=40412">40412</a>
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<tr>
<th>Summary</th>
<td>Unconvertable type leads to invalid WebAssembly
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
<tr>
<th>OS</th>
<td>other
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: WebAssembly
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>dan433584@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>On this C++ testcase:
class c;
template<class> class basic_streambuf {
virtual c seekoff(unsigned);
};
basic_streambuf<char> x;
Clang produces LLVM IR for wasm32 containing this:
@_ZTV15basic_streambufIcE = linkonce_odr hidden unnamed_addr constant { [3 x
i8*] } { [3 x i8*] [i8* null, i8* bitcast ({ i8*, i8* }*
@_ZTI15basic_streambufIcE to i8*), i8* bitcast (void ()*
@_ZN15basic_streambufIcE7seekoffEj to i8*)] }, comdat, align 4
declare void @_ZN15basic_streambufIcE7seekoffEj() unnamed_addr
seekoff's argument types don't match the types in the C++ source file, which
causes wasm-ld to ultimately complain about the signature mismatch.
This is a reduced form of code in libcxx which causes wasm-ld to complain when
linking C++ programs:
wasm-ld: warning: function signature mismatch:
_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE7seekoffExNS_8ios_base7seekdirEj
<span class="quote">>>> defined as (i32, i32, i64, i32, i32) -> void in [...]/libc++.a(ios.cpp.obj)
>>> defined as () -> void in [...]/libc++.a(iostream.cpp.obj)</span ></pre>
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