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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - clang-cl: vtordisp thunks not emitted for functions with class template specializations in their signatures"
href="https://llvm.org/bugs/show_bug.cgi?id=25641">25641</a>
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<th>Summary</th>
<td>clang-cl: vtordisp thunks not emitted for functions with class template specializations in their signatures
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>stephan.bergmann.secondary@googlemail.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>On recent trunk:
<span class="quote">> $ cat test.cc
> struct Color {};
> template<typename> struct SharedPtr {};
> struct Canvas {
> virtual ~Canvas() {}
> virtual void getClip() = 0;
> virtual SharedPtr<Color> createColor() = 0;
> };
> struct BitmapCanvas: virtual Canvas {};
> struct ImplCanvas: virtual Canvas {
> virtual ~ImplCanvas();
> void getClip() override;
> SharedPtr<Color> createColor() override;
> };
> struct ImplBitmapCanvas: virtual BitmapCanvas, virtual ImplCanvas {
> virtual ~ImplBitmapCanvas();
> };
> ImplBitmapCanvas::~ImplBitmapCanvas() {}
> ImplBitmapCanvas c;</span >
<span class="quote">> $ clang-cl -c test.cc</span >
<span class="quote">> $ llvm-nm test.obj | grep -F '?getClip@ImplCanvas@@$'
> 00000000 T ?getClip@ImplCanvas@@$4PPPPPPPM@A@EAAXXZ
> 00000000 T ?getClip@ImplCanvas@@$R4BA@M@PPPPPPPM@BA@EAAXXZ</span >
<span class="quote">> $ llvm-nm test.obj | grep -F '?createColor@ImplCanvas@@$'
> U ?createColor@ImplCanvas@@$4PPPPPPPM@A@EAA?AU?$SharedPtr@UColor@@@@XZ
> U ?createColor@ImplCanvas@@$R4BA@M@PPPPPPPM@BA@EAA?AU?$SharedPtr@UColor@@@@XZ</span >
The vtordisp thunks for getClip are emitted, while those for createColor are
erroneously missing.
The reason is that CodeGenVTabels::maybeEmitThunkForVtable
(lib/CodeGen/CGVtables.cpp) returns early if !isFuncTypeConvertible, which hits
here as the ClassTemplateSpecializationDecl for SharedPtr<Color> is
!isCompleteDefinition, as there's no code in Sema that happens to call
Sema::RequireCompleteType -> Sema::InstantiateClassTemplateSpecialization on
it.</pre>
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</p>
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