3bc765dbbf
This is a reduced test case from a crash we've observed in the past. The assertion that this test triggers is: ``` Assertion failed: ((Pos == ImportedDecls.end() || Pos->second == To) && "Try to import an already imported Decl"), function MapImported, file ASTImporter.cpp, line 10494. ``` In a non-asserts build we crash later on in the ASTImporter. The root cause is, as the assertion above points out, that we erroneously replace an existing `From->To` decl mapping with a `To` decl that isn't complete. Then we try to complete it but it has no definition and we dereference a nullptr. The reason this happens is basically what's been described in https://reviews.llvm.org/D67803?id=220956#1676588 The dylib contains a definition of `Service` which is different to the one in the main executable. When we start dumping the children of the variable we're printing, we start completing it's members, `ASTImport`ing fields in the process. When the ASTImporter realizes there's been a name conflict (i.e., a structural mismatch on the `Service` type) it would usually report back an error. However, LLDB uses `ODRHandlingType::Liberal`, which means we create a new decl for the ODR'd type instead of re-using the previously mapped decl. Eventually this leads us to crash. Ideally we'd be using `ODRHandlingType::Conservative` and warn/error, though LLDB relies on this in some cases (particularly for distinguishing template specializations, though maybe there's better a way to deal with those). We should really warn the user when this happens and not crash. To avoid the crash we'd need to know to not create a decl for the ODR violation, and instead re-use the definition we've previously seen. Though I'm not yet sure that's viable for all of LLDB's use-cases (where ODR violations might legimiately occur in a program, e.g., with opaque definitions, etc.).
15 lines
209 B
C++
15 lines
209 B
C++
#include "plugin.h"
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#include "service.h"
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struct Proxy : public Service {
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State *proxyState;
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};
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Proxy *gProxyThis = 0;
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extern "C" {
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void plugin_init() { gProxyThis = new Proxy; }
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void plugin_entry() {}
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}
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