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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 - clang-cl doesn't output the template parameter on variable templates"
href="https://bugs.llvm.org/show_bug.cgi?id=39616">39616</a>
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<th>Summary</th>
<td>clang-cl doesn't output the template parameter on variable templates
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>DebugInfo
</td>
</tr>
<tr>
<th>Assignee</th>
<td>rnk@google.com
</td>
</tr>
<tr>
<th>Reporter</th>
<td>zturner@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>aleksandr.urakov@jetbrains.com, jdevlieghere@apple.com, llvm-bugs@lists.llvm.org, mosescu@google.com
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<p>
<div>
<pre>template<typename T>
constexpr T Pi = T(3.1415926);
template<typename T>
extern void unresolved(const T *);
int main(int argc, char **argv) {
unresolved(&Pi<int>);
unresolved(&Pi<double>);
unresolved(&Pi<long double>);
return (int)(Pi<int> + Pi<double> + Pi<long double>);
}
compile and link with both MSVC and clang:
MSVC:
1) cl.exe /Z7 /GS- /GR- /Fovariable-cl.obj /c variable.cpp
2) link.exe /debug:full /incremental:no /nodefaultlib /force:unresolved
/entry:main variable-cl.obj
Clang:
1) clang-cl.exe /Z7 /GS- /GR- -Xclang -fkeep-static-consts /c variable.cpp
2) lld-link.exe /debug:full /incremental:no /nodefaultlib /force:unresolved
/entry:main variable.obj
Then dump the globals from each and compare:
$ bin\llvm-pdbutil.exe dump -globals variable.pdb
Global Symbols
============================================================
Records
20 | S_PROCREF [size = 20] `main`
module = 1, sum name = 0, offset = 52
40 | S_LDATA32 [size = 20] `Pi`
type = 0x1003 (const int), addr = 0002:0000
60 | S_LDATA32 [size = 20] `Pi`
type = 0x1004 (const double), addr = 0002:0008
80 | S_LDATA32 [size = 20] `Pi`
type = 0x1004 (const double), addr = 0002:0016
$ bin\llvm-pdbutil.exe dump -globals variable-cl.pdb
Global Symbols
============================================================
Records
20 | S_PROCREF [size = 20] `main`
module = 1, sum name = 0, offset = 176
40 | S_LDATA32 [size = 24] `Pi<int>`
type = 0x1051 (const int), addr = 0002:0000
64 | S_LDATA32 [size = 28] `Pi<double>`
type = 0x1052 (const double), addr = 0002:0008
92 | S_LDATA32 [size = 32] `Pi<long double>`
type = 0x1052 (const double), addr = 0002:0016
As you can see, MSVC puts the template parameter type into the name, whereas we
do not.
The result of this is that in LLDB we can't view variable templates because we
can't look them up (there is actually another bug preventing this as well on
the LLDB side, but fixing this is step 1).</pre>
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