clangd crashes when including some standard library headers in the global module fragment #80570
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crash
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EugeneZelenko
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clangd
crash
|
@llvm/issue-subscribers-clangd Author: None (marwing)
The following code currently reliably crashes clangd.
I am using a nightly llvm build (d9850fe) with current neovim HEAD and the built-in lsp client.
I bisected this crash to a0b6747. Considering this is only using libc++ headers from the same commit, I don't include preprocessed sources. If you need them anyway, I can provide them. Reproducer: // test.cpp
module;
// any one off these is enough to crash clangd
// #include <iostream>
#include <string>
// #include <string_view>
// #include <cmath>
// #include <system_error>
// #include <new>
// #include <bit>
// probably many more
// only ok with libc++, not the system provided libstdc++ 13.2.1
#include <iosfwd>
// these are ok
#include <cstddef>
#include <cerrno>
export module test;<details> </details> <details> </details> |
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Please note that module support of clangd is incomplete and tracked at clangd/clangd#1293. |
I know, thanks. I'm just toying around with modules to improve my understanding of them and a crash is bad regardless. |
CLRN
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Feb 15, 2024
This fix partially reverts llvm@a0b6747. The serialization part is restored to the state prior to the mentioned commit as it causing issue with reading back Decl. ODR checks logic is kept in place. Close llvm#80570.
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The reason may be that the clangd serialize the headers into preamble files with ODRHash and when we read them we skipped the ODRHash. |
ChuanqiXu9
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Feb 20, 2024
Close llvm#80570. In llvm@a0b6747, we skipped ODR checks for decls in GMF. Then it should be natural to skip storing the ODR values in BMI. Generally it should be fine as long as the writer and the reader keep consistent. However, the use of preamble in clangd shows the tricky part. For, ``` // test.cpp module; // any one off these is enough to crash clangd // #include <iostream> // #include <string_view> // #include <cmath> // #include <system_error> // #include <new> // #include <bit> // probably many more // only ok with libc++, not the system provided libstdc++ 13.2.1 // these are ok export module test; ``` clangd will store the headers as preamble to speedup the parsing and the preamble reuses the serialization techniques. (Generally we'd call the preamble as PCH. However it is not true strictly. I've tested the PCH wouldn't be problematic.) However, the tricky part is that the preamble is not modules. It literally serialiaze and deserialize things. So before clangd parsing the above test module, clangd will serialize the headers into the preamble. Note that there is no concept like GMF now. So the ODR bits are stored. However, when clangd parse the file actually, the decls from preamble are thought as in GMF literally, then hte ODR bits are skipped. Then mismatch happens. To solve the problem, this patch adds another bit for decls to record whether or not the ODR bits are skipped.
ChuanqiXu9
added a commit
that referenced
this issue
Feb 20, 2024
Close #80570. In a0b6747, we skipped ODR checks for decls in GMF. Then it should be natural to skip storing the ODR values in BMI. Generally it should be fine as long as the writer and the reader keep consistent. However, the use of preamble in clangd shows the tricky part. For, ``` // test.cpp module; // any one off these is enough to crash clangd // #include <iostream> // #include <string_view> // #include <cmath> // #include <system_error> // #include <new> // #include <bit> // probably many more // only ok with libc++, not the system provided libstdc++ 13.2.1 // these are ok export module test; ``` clangd will store the headers as preamble to speedup the parsing and the preamble reuses the serialization techniques. (Generally we'd call the preamble as PCH. However it is not true strictly. I've tested the PCH wouldn't be problematic.) However, the tricky part is that the preamble is not modules. It literally serialiaze and deserialize things. So before clangd parsing the above test module, clangd will serialize the headers into the preamble. Note that there is no concept like GMF now. So the ODR bits are stored. However, when clangd parse the file actually, the decls from preamble are thought as in GMF literally, then hte ODR bits are skipped. Then mismatch happens. To solve the problem, this patch adds another bit for decls to record whether or not the ODR bits are skipped.
EugeneZelenko
added
clang:frontend
|
@llvm/issue-subscribers-clang-frontend Author: None (marwing)
The following code currently reliably crashes clangd.
I am using a nightly llvm build (d9850fe) with current neovim HEAD and the built-in lsp client.
I bisected this crash to a0b6747. Considering this is only using libc++ headers from the same commit, I don't include preprocessed sources. If you need them anyway, I can provide them. Reproducer: // test.cpp
module;
// any one off these is enough to crash clangd
// #include <iostream>
#include <string>
// #include <string_view>
// #include <cmath>
// #include <system_error>
// #include <new>
// #include <bit>
// probably many more
// only ok with libc++, not the system provided libstdc++ 13.2.1
#include <iosfwd>
// these are ok
#include <cstddef>
#include <cerrno>
export module test;<details> </details> <details> </details> |
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/cherry-pick 49775b1 |
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Although we announced that the support for C++20 modules in clangd is broken, there are already a lot of people tried to use clangd with modules in some level. So it should be helpful to backport this to clang18 as well to improve the user experience as much as possible. |
llvmbot
pushed a commit
to llvmbot/llvm-project
that referenced
this issue
Feb 20, 2024
Close llvm#80570. In llvm@a0b6747, we skipped ODR checks for decls in GMF. Then it should be natural to skip storing the ODR values in BMI. Generally it should be fine as long as the writer and the reader keep consistent. However, the use of preamble in clangd shows the tricky part. For, ``` // test.cpp module; // any one off these is enough to crash clangd // #include <iostream> // #include <string_view> // #include <cmath> // #include <system_error> // #include <new> // #include <bit> // probably many more // only ok with libc++, not the system provided libstdc++ 13.2.1 // these are ok export module test; ``` clangd will store the headers as preamble to speedup the parsing and the preamble reuses the serialization techniques. (Generally we'd call the preamble as PCH. However it is not true strictly. I've tested the PCH wouldn't be problematic.) However, the tricky part is that the preamble is not modules. It literally serialiaze and deserialize things. So before clangd parsing the above test module, clangd will serialize the headers into the preamble. Note that there is no concept like GMF now. So the ODR bits are stored. However, when clangd parse the file actually, the decls from preamble are thought as in GMF literally, then hte ODR bits are skipped. Then mismatch happens. To solve the problem, this patch adds another bit for decls to record whether or not the ODR bits are skipped. (cherry picked from commit 49775b1)
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/pull-request #82309 |
llvmbot
pushed a commit
to llvmbot/llvm-project
that referenced
this issue
Feb 21, 2024
Close llvm#80570. In llvm@a0b6747, we skipped ODR checks for decls in GMF. Then it should be natural to skip storing the ODR values in BMI. Generally it should be fine as long as the writer and the reader keep consistent. However, the use of preamble in clangd shows the tricky part. For, ``` // test.cpp module; // any one off these is enough to crash clangd // #include <iostream> // #include <string_view> // #include <cmath> // #include <system_error> // #include <new> // #include <bit> // probably many more // only ok with libc++, not the system provided libstdc++ 13.2.1 // these are ok export module test; ``` clangd will store the headers as preamble to speedup the parsing and the preamble reuses the serialization techniques. (Generally we'd call the preamble as PCH. However it is not true strictly. I've tested the PCH wouldn't be problematic.) However, the tricky part is that the preamble is not modules. It literally serialiaze and deserialize things. So before clangd parsing the above test module, clangd will serialize the headers into the preamble. Note that there is no concept like GMF now. So the ODR bits are stored. However, when clangd parse the file actually, the decls from preamble are thought as in GMF literally, then hte ODR bits are skipped. Then mismatch happens. To solve the problem, this patch adds another bit for decls to record whether or not the ODR bits are skipped. (cherry picked from commit 49775b1)
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The following code currently reliably crashes clangd.
I am using a nightly llvm build (d9850fe) with current neovim HEAD and the built-in lsp client.
I bisected this crash to a0b6747.
Considering this is only using libc++ headers from the same commit, I don't include preprocessed sources. If you need them anyway, I can provide them.
Reproducer:
clangd log
Just in case another log is helpful,
clangd --checkfails with the same assertion.The text was updated successfully, but these errors were encountered: