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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - In Sema::SubstExceptionSpec: Assertion `ESI.Type != EST_Uninstantiated' failed"
href="https://bugs.llvm.org/show_bug.cgi?id=43151">43151</a>
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<th>Summary</th>
<td>In Sema::SubstExceptionSpec: Assertion `ESI.Type != EST_Uninstantiated' failed
</td>
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<th>Product</th>
<td>clang
</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>Linux
</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>Frontend
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>aaronpuchert@alice-dsl.net
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<pre>Created <span class=""><a href="attachment.cgi?id=22445" name="attach_22445" title="Small reproducer for the bug, compile with -std=c++17.">attachment 22445</a> <a href="attachment.cgi?id=22445&action=edit" title="Small reproducer for the bug, compile with -std=c++17.">[details]</a></span>
Small reproducer for the bug, compile with -std=c++17.
Compiling the following code with "-fsyntax-only -std=c++17" produces an
assertion failure:
template<typename T>
struct X {
using self = X<T>;
template<bool noex>
void f() noexcept(noex)
{
auto x = &self::f<noex>;
}
};
void g()
{
X<int> x;
x.f<true>();
}
The trace shows:
1. <eof> parser at end of file
2. template-crash.cpp:6:8: instantiating function definition
'X<int>::f<true>'
The issue disappears when removing "-std=c++17", probably because the exception
specification is not part of the type then.
The function is called from clang::Sema::SubstituteExplicitTemplateArguments,
where we have EPI.ExceptionSpec.Type = clang::EST_Uninstantiated and
EPI.ExceptionSpec.SourceDecl = Function. On the other hand, the type of
EPI.ExceptionSpec.SourceTemplate has an ExceptionSpec with Type =
clang::EST_DependentNoexcept. So it seems we should be passing that one to
Sema::SubstExceptionSpec instead.
Indeed, the following seems to fix the assertion (and not introduce new
issues):
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -3112,6 +3112,13 @@ Sema::SubstituteExplicitTemplateArguments(
// so substitution into the type must also substitute into the exception
// specification.
SmallVector<QualType, 4> ExceptionStorage;
+ if (EPI.ExceptionSpec.Type == EST_Uninstantiated) {
+ assert(Function == EPI.ExceptionSpec.SourceDecl);
+ const auto *TplType = EPI.ExceptionSpec.SourceTemplate->getType()
+ ->getAs<FunctionProtoType>();
+ EPI.ExceptionSpec = TplType->getExtProtoInfo().ExceptionSpec;
+ assert(EPI.ExceptionSpec.Type != EST_Uninstantiated);
+ }
if (getLangOpts().CPlusPlus17 &&
SubstExceptionSpec(
Function->getLocation(), EPI.ExceptionSpec, ExceptionStorage,
But this seems like a hack, since in other instances the ExceptionSpec is
already instantiated correctly.</pre>
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