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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 --- - Unexpected divergence between -fmodules and not (due to "<undeserialized declarations>"?)"
href="https://llvm.org/bugs/show_bug.cgi?id=24425">24425</a>
</td>
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<tr>
<th>Summary</th>
<td>Unexpected divergence between -fmodules and not (due to "<undeserialized declarations>"?)
</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>All
</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>Modules
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>chisophugis@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
</td>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Here's an example where -fmodules has an unexpected effect on the output. We
seem to not be deserializing some stuff.
a.cpp:
#include "a.h"
// Modules version has Foo<int>::s_bar undefined.
// Nonmodules version has Foo<int>::s_bar defined.
template <typename T> char Foo<T>::s_bar;
a.h:
template <class T> struct Foo { static char s_bar; };
char baz() { return Foo<int>::s_bar; }
module.modulemap:
module a {
header "a.h"
}
repro.sh:
BIN=~/pg/d+a/bin
CLANGXX=$BIN/clang++
NM=$BIN/llvm-nm
CACHE_PATH=./cache_path
rm -rf $CACHE_PATH
$CLANGXX -c a.cpp -o a.o -fmodules-cache-path=$CACHE_PATH -fmodules && $NM a.o
| grep 's_bar'
$CLANGXX -c a.cpp -o a.o && $NM a.o | grep 's_bar'
Observed output on trunk:
% ./repro.sh
U __ZN3FooIiE5s_barE
0000000000000010 S __ZN3FooIiE5s_barE
Adding `-Xclang -ast-dump` to the compiler invocations in repro.sh suggests
that the issue is that we aren't deserializing `Foo<int>::s_bar`
(-fmodules)
...
|-ImportDecl 0x7f9b838394f8 <a.cpp:1:1> col:1 implicit a
|-VarDecl 0x7f9b84008058 parent 0x7f9b83839738 prev 0x7f9b84007fe8 <line:4:1,
col:36> col:36 s_bar 'char'
`-<undeserialized declarations>
(no -fmodules)
...
|-ClassTemplateDecl 0x7fc28883d910 <./a.h:1:1, col:52> col:27 Foo
| |-TemplateTypeParmDecl 0x7fc28883d7c8 <col:11, col:17> col:17 class T
| |-CXXRecordDecl 0x7fc28883d880 <col:20, col:52> col:27 struct Foo definition
| | |-CXXRecordDecl 0x7fc288885a00 <col:20, col:27> col:27 implicit struct Foo
| | `-VarDecl 0x7fc288885aa0 <col:33, col:45> col:45 s_bar 'char' static
| `-ClassTemplateSpecializationDecl 0x7fc288885c48 <col:1, col:52> col:27
struct Foo definition
| |-TemplateArgument type 'int'
| |-CXXRecordDecl 0x7fc288885e38 prev 0x7fc288885c48 <col:20, col:27> col:27
implicit struct Foo
| `-VarDecl 0x7fc288885ec8 <col:33, col:45> col:45 used s_bar 'char' static
|-FunctionDecl 0x7fc288885b50 <line:2:1, col:38> col:6 baz 'char (void)'
| `-CompoundStmt 0x7fc288885fd0 <col:12, col:38>
| `-ReturnStmt 0x7fc288885fb8 <col:14, col:31>
| `-ImplicitCastExpr 0x7fc288885fa0 <col:21, col:31> 'char'
<LValueToRValue>
| `-DeclRefExpr 0x7fc288885f68 <col:21, col:31> 'char' lvalue Var
0x7fc288885ec8 's_bar' 'char'
|-VarDecl 0x7fc288886280 parent 0x7fc28883d880 prev 0x7fc288885aa0 <a.cpp:4:1,
col:36> col:36 s_bar 'char'
`-VarDecl 0x7fc288886320 parent 0x7fc288885c48 prev 0x7fc288885ec8 <col:23,
col:36> col:36 used s_bar 'char'</pre>
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