digitalmars.D.bugs - [Issue 22218] New: Dynamic casts across binary boundaries can easily
- d-bugmail puremagic.com (71/71) Aug 16 2021 https://issues.dlang.org/show_bug.cgi?id=22218
https://issues.dlang.org/show_bug.cgi?id=22218 Issue ID: 22218 Summary: Dynamic casts across binary boundaries can easily fail Product: D Version: D2 Hardware: All OS: All Status: NEW Severity: major Priority: P1 Component: druntime Assignee: nobody puremagic.com Reporter: kinke gmx.net If there are TypeInfo duplicates in multiple binaries of a process, e.g., from templates instantiated in multiple binaries, dynamic casts can fail. E.g., the following code fails with LDC (v1.27) and GDC (v10.3) on Linux, somehow works with DMD on Linux though, and fails on Windows in general: ``` class C() {} version (DLL) { version (Windows) { import core.sys.windows.dll; mixin SimpleDllMain; } pragma(mangle, "foo") export Object foo(Object o) { assert(cast(C!()) o); // <-- fails here return new C!(); } } else { T getFunc(T)(const(char)* sym, string thisExePath) { import core.runtime : Runtime; version (Windows) { import core.sys.windows.winbase : GetProcAddress; return cast(T) Runtime.loadLibrary("dynamiccast.dll") .GetProcAddress(sym); } else version (Posix) { import core.sys.posix.dlfcn : dlsym; import core.stdc.string : strrchr; auto name = thisExePath ~ '\0'; const pathlen = strrchr(name.ptr, '/') - name.ptr + 1; name = name[0 .. pathlen] ~ "dynamiccast.so"; return cast(T) Runtime.loadLibrary(name) .dlsym(sym); } else static assert(0); } void main(string[] args) { auto c = new C!(); auto o = getFunc!(Object function(Object))("foo", args[0])(c); assert(cast(C!()) o); } } ``` To be built and run like this: $ dmd -shared dynamiccast.d -version=DLL -ofdynamiccast.so -fPIC -defaultlib=libphobos2.so $ dmd dynamiccast.d -ofdynamiccast -fPIC -defaultlib=libphobos2.so $ ./dynamiccast Related: https://issues.dlang.org/show_bug.cgi?id=7020 --
Aug 16 2021