digitalmars.D.bugs - [Issue 18784] New: Segfault due to dmd codegen interfacing with C++
- d-bugmail puremagic.com (55/55) Apr 20 2018 https://issues.dlang.org/show_bug.cgi?id=18784
https://issues.dlang.org/show_bug.cgi?id=18784 Issue ID: 18784 Summary: Segfault due to dmd codegen interfacing with C++ Product: D Version: D2 Hardware: x86_64 OS: Linux Status: NEW Severity: blocker Priority: P1 Component: dmd Assignee: nobody puremagic.com Reporter: atila.neves gmail.com The following two files when compiled and linked result in a segfault when using dmd but not ldc2: d.d: extern(C++) { struct Struct { pragma(mangle, "_ZN6StructC1Ei") this(int); pragma(mangle, "_ZN6StructC1EOS_") this(Struct*); this(Struct other) { this(&other); } } } void main() { auto s = Struct(Struct(7)); } cpp.cpp: #include <stdio.h> struct Struct { Struct(int); Struct(Struct&&); }; Struct::Struct(int) { printf("Oops\n"); } Struct::Struct(Struct&&) { } To reproduce: clang++ -g -c cpp.cpp ./d Preliminary analysis: Removing the printf from the C++ constructor prevents the segfault. In fact, it seems that the return value of printf is used to deference a pointer. Without the printf, rax has the value it had before and everything works. The bug only manifests if a temporary is passed directly to the by-value D constructor. Changing `auto s = Struct(Struct(7))` to: auto tmp = Struct(7); auto s = Struct(tmp); Makes the bug disappear. Using ldc2 works, suggesting that the issue is due to dmd's codegen, especially given what happens to rax as stated above. This issue is preventing "just works" C++ integration. --
Apr 20 2018