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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - UBSan fails to deduplicate reports from template instantiations"
href="https://llvm.org/bugs/show_bug.cgi?id=26846">26846</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>UBSan fails to deduplicate reports from template instantiations
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>vonosmas@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Arguably, it should.
$ cat tmp/a.cc
#include <stdio.h>
struct C {
void print(int x) { fprintf(stderr, "This is %d\n", x); }
};
template <typename T>
void f(C* c, T t) {
c->print((int)t);
}
int main() {
C* c = NULL;
f<int>(c, 2);
f<double>(c, 3.0);
return 0;
}
$ ./bin/clang++ -fsanitize=null tmp/a.cc -O1 ; ./a.out
tmp/a.cc:9:3: runtime error: member call on null pointer of type 'C'
This is 2
tmp/a.cc:9:3: runtime error: member call on null pointer of type 'C'
This is 3
Sadly, we print the error twice for the exact same source location and type.
This what deduplication was implemented for, but for some reason it's not
triggering here, although the "static data" we pass to the handlers is exactly
the same:
$ ./bin/clang++ -fsanitize=null tmp/a.cc -O1 -S -emit-llvm -o a.ll
$ cat a.ll
<...>
@.src = private unnamed_addr constant [9 x i8] c"tmp/a.cc\00", align 1
@0 = private unnamed_addr constant { i16, i16, [4 x i8] } { i16 -1, i16 0, [4 x
i8] c"'C'\00" }
@1 = private unnamed_addr global { { [9 x i8]*, i32, i32 }, { i16, i16, [4 x
i8] }*, i64, i8 } { { [9 x i8]*, i32, i32 } { [9 x i8]* @.src, i32 9, i32 3 },
{ i16, i16, [4 x i8] }* @0, i64 0, i8 4 }
<....>
@2 = private unnamed_addr global { { [9 x i8]*, i32, i32 }, { i16, i16, [4 x
i8] }*, i64, i8 } { { [9 x i8]*, i32, i32 } { [9 x i8]* @.src, i32 9, i32 3 },
{ i16, i16, [4 x i8] }* @0, i64 0, i8 4 }
define linkonce_odr void @_Z1fIiEvP1CT_(%struct.C* %c, i32 %t) #1 comdat {
<...>
tail call void @__ubsan_handle_type_mismatch(i8* bitcast ({ { [9 x i8]*, i32,
i32 }, { i16, i16, [4 x i8] }*, i64, i8 }* @1 to i8*), i64 %1) #4, !nosanitize
!1
<...>
}
define linkonce_odr void @_Z1fIdEvP1CT_(%struct.C* %c, double %t) #1 comdat {
<...>
tail call void @__ubsan_handle_type_mismatch(i8* bitcast ({ { [9 x i8]*, i32,
i32 }, { i16, i16, [4 x i8] }*, i64, i8 }* @2 to i8*), i64 %1) #4, !nosanitize
!1
<...>
}</pre>
</div>
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