martong added a comment.
In case of the reproducer the problem is that we clear the switch ids in
GetExternalDeclStmt. But we read the SwitchCase with the same ID twice from the
same call of `GetExternalDeclStmt` (**//bold-italic//** in the below call
stacks):
- 1)
clang::ASTReader::RecordSwitchCaseID (this=0x4d5710, SC=0x5022f0, ID=0) at
../../git/llvm-project/clang/lib/Serialization/ASTReader.cpp:9070
0x00007ffff0313097 in clang::ASTRecordReader::recordSwitchCaseID
(this=0x7fffffff7ca8, SC=0x5022f0, ID=0) at
../../git/llvm-project/clang/include/clang/Serialization/ASTRecordReader.h:331
0x00007ffff0300ebc in clang::ASTStmtReader::VisitSwitchCase
(this=0x7fffffff7c98, S=0x5022f0) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:165
0x00007ffff0300f3f in clang::ASTStmtReader::VisitCaseStmt (this=0x7fffffff7c98,
S=0x5022f0) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:171
0x00007ffff031e768 in clang::StmtVisitorBase<std::add_pointer,
clang::ASTStmtReader, void>::Visit (this=0x7fffffff7c98, S=0x5022f0) at
tools/clang/include/clang/AST/StmtNodes.inc:561
0x00007ffff0312b7c in clang::ASTReader::ReadStmtFromStream (this=0x4d5710,
F=...) at ../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:3896
0x00007ffff030eb2e in clang::ASTReader::ReadStmt (this=0x4d5710, F=...) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:2696
0x00007ffff0312e2d in clang::ASTReader::ReadExpr (this=0x4d5710, F=...) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:2705
0x00007ffff01cbb10 in clang::ASTRecordReader::readExpr (this=0x7fffffff8450) at
../../git/llvm-project/clang/include/clang/Serialization/ASTRecordReader.h:131
0x00007ffff0293b23 in clang::ASTDeclReader::VisitVarDeclImpl
(this=0x7fffffff8408, VD=0x5010d0) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderDecl.cpp:1419
0x00007ffff02c40ad in clang::ASTDeclReader::VisitVarDecl (this=0x7fffffff8408,
VD=0x5010d0) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderDecl.cpp:371
0x00007ffff02be24c in clang::declvisitor::Base<std::add_pointer,
clang::ASTDeclReader, void>::Visit (this=0x7fffffff8408, D=0x5010d0) at
tools/clang/include/clang/AST/DeclNodes.inc:453
0x00007ffff028e5ca in clang::ASTDeclReader::Visit (this=0x7fffffff8408,
D=0x5010d0) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderDecl.cpp:519
0x00007ffff02b938f in clang::ASTReader::ReadDeclRecord (this=0x4d5710, ID=29)
at ../../git/llvm-project/clang/lib/Serialization/ASTReaderDecl.cpp:4044
0x00007ffff018c714 in clang::ASTReader::GetDecl (this=0x4d5710, ID=29) at
../../git/llvm-project/clang/lib/Serialization/ASTReader.cpp:7422
0x00007ffff021f9fa in clang::ASTReader::ReadDecl (this=0x4d5710, F=...,
R=llvm::SmallVector of Size 3, Capacity 64 = {...}, I=@0x7fffffff9830: 3) at
../../git/llvm-project/clang/include/clang/Serialization/ASTReader.h:1863
0x00007ffff021f9a6 in clang::ASTRecordReader::readDecl (this=0x7fffffff9818) at
../../git/llvm-project/clang/include/clang/Serialization/ASTRecordReader.h:192
0x00007ffff0313d88 in clang::ASTStmtReader::readDecl (this=0x7fffffff9808) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:92
0x00007ffff0301d6a in clang::ASTStmtReader::VisitDeclStmt (this=0x7fffffff9808,
S=0x5010b0) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:340
0x00007ffff031e078 in clang::StmtVisitorBase<std::add_pointer,
clang::ASTStmtReader, void>::Visit (this=0x7fffffff9808, S=0x5010b0) at
tools/clang/include/clang/AST/StmtNodes.inc:97
0x00007ffff0312b7c in clang::ASTReader::ReadStmtFromStream (this=0x4d5710,
F=...) at ../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:3896
**//0x00007ffff019a07c in clang::ASTReader::GetExternalDeclStmt (this=0x4d5710,
Offset=107033) at
../../git/llvm-project/clang/lib/Serialization/ASTReader.cpp:7476//**
- 2)
clang::ASTReader::RecordSwitchCaseID (this=0x4d5710, SC=0x502440, ID=0) at
../../git/llvm-project/clang/lib/Serialization/ASTReader.cpp:9070
0x00007ffff0313097 in clang::ASTRecordReader::recordSwitchCaseID
(this=0x7fffffff9818, SC=0x502440, ID=0) at
../../git/llvm-project/clang/include/clang/Serialization/ASTRecordReader.h:331
0x00007ffff0300ebc in clang::ASTStmtReader::VisitSwitchCase
(this=0x7fffffff9808, S=0x502440) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:165
0x00007ffff030102f in clang::ASTStmtReader::VisitDefaultStmt
(this=0x7fffffff9808, S=0x502440) at
../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:182
0x00007ffff031e780 in clang::StmtVisitorBase<std::add_pointer,
clang::ASTStmtReader, void>::Visit (this=0x7fffffff9808, S=0x502440) at
tools/clang/include/clang/AST/StmtNodes.inc:567
0x00007ffff0312b7c in clang::ASTReader::ReadStmtFromStream (this=0x4d5710,
F=...) at ../../git/llvm-project/clang/lib/Serialization/ASTReaderStmt.cpp:3896
**//0x00007ffff019a07c in clang::ASTReader::GetExternalDeclStmt (this=0x4d5710,
Offset=107033) at
../../git/llvm-project/clang/lib/Serialization/ASTReader.cpp:7476
//**
(In Bruno's modified example we always see the 2) call stack, meaning that the
ids are cleared and everything is ok.)
My first attempt for the fix was to try to call `ClearSwitchCaseIDs` in
VisitVarDecl, but that fired the other assertion in `getSwitchCaseWithID` for
some other test cases.
The second attempt was to clear the SwitchCaseIDs in
`ASTStmtReader::VisitSwitchStmt` and that indeed succeeded with the particular
reproducer, but the original problem (reported by @vabridgers) was still
crashing. Unfortunately, I could not create another minimal reproducer for this
attempt, seems like there must be some different order of lazy loading of
bodies to get the crash. So, I suspected there is something fundamentally wrong
with the tracking of the SwitchCases and I came up with this patch.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D82940/new/
https://reviews.llvm.org/D82940
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