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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Name mangling different msvc/clang for covariant return type"
href="https://bugs.llvm.org/show_bug.cgi?id=40138">40138</a>
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<th>Summary</th>
<td>Name mangling different msvc/clang for covariant return type
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>7.0
</td>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>-New Bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jvapen@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=21267" name="attach_21267" title="Full reproduction">attachment 21267</a> <a href="attachment.cgi?id=21267&action=edit" title="Full reproduction">[details]</a></span>
Full reproduction
Incorrect mangling of the return type, causes build created via clang to load
extra DLLs.
Both compilers generate the symbol:
?clone@Derived@@EEBAPEAV1@XZ
MSVC generates a second symbol:
?clone@Derived@@QEBAPEAVInterface@@XZ
Clang generates a second symbol:
?clone@Derived@@AEBAPEAVInterface@@XZ
(See @@AE instead of @@QE)
RUN.BAT
------
cl.exe /nologo /c /EHsc /fp:precise /FS /std:c++17 /MDd /bigobj t.cpp
move t.obj t.msvc.obj
C:\DevStudio\LLVM_7_0_0\bin\clang-cl.exe /nologo /c /EHsc /fp:precise /FS
/std:c++17 -fms-compatibility-version=19.11 /MDd /bigobj t.cpp
move t.obj t.clang.obj
dumpbin /SYMBOLS t.msvc.obj | grep "External" >t.msvc.sym
dumpbin /SYMBOLS t.clang.obj | grep "External" >t.clang.sym
echo MSVC
grep "?clone@Derived@@EEBAPEAV1@XZ" t.msvc.sym
grep "?clone@Derived@@QEBAPEAVInterface@@XZ" t.msvc.sym
echo NOT GENERATED
grep "?clone@Derived@@AEBAPEAVInterface@@XZ" t.msvc.sym
echo CLANG
grep "?clone@Derived@@EEBAPEAV1@XZ" t.clang.sym
grep "?clone@Derived@@QEBAPEAVInterface@@XZ" t.clang.sym
echo NOT GENERATED
grep "?clone@Derived@@AEBAPEAVInterface@@XZ" t.clang.sym
t.cpp
-----
class Interface {
public:
virtual ~Interface() = default;
virtual Interface *clone() const;
};
class __declspec(dllexport) A {
public:
explicit A();
virtual ~A();
};
class __declspec(dllexport) B : public A,
public Interface {
public:
virtual ~B();
};
class __declspec(dllexport) Derived : public B {
public:
explicit Derived();
private:
virtual Derived *clone() const {
return new Derived{*this};
}
};</pre>
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