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Re: Unability to debug [message #41861 is a reply to message #41537]

Fri, 31 January 2014 14:44

Shire
Messages: 41
Registered: September 2006
Location: Russia, Yamal peninsula

Member

GDB_MI2 crashes when debugging by TheIDE built with MSC compiler.
(Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.40219.01 for 80x86, for me).

Debugger crashes at this harmless place:
uppsrc/ide/Builders/Gdb_MI2.cpp

MIValue Gdb_MI2::MICmd(const char *cmdLine)
{ // ...
	return ReadGdb();
}

Return by value operation destructs MIValue instance. Let's see at MIValue class:
uppsrc/ide/Builders/MIValue.h

MIValue &operator=(pick_ MIValue &v);
MIValue &operator=(String const &s);

MIValue(MIValue pick_ &v);
MIValue(String const &s);

operator String&() { return Get(); }
operator const String &() const { return Get(); }

After some debugging I found fundamental difference Smile

uppsrc/Core/Defs.h

#ifdef COMPILER_MSC
#define pick_
#else
#define pick_ const
#endif

Smart Microsoft compiler, when it can not find copy constructor of MIValue (because _pick is not const), copies instance via const String& conversion:

return MIValue((const String&)ReadGdb());

May be, this method was preferred by compiler because constantness of returning operator. Solution is make String& constuctor explicit and replace operator= with Set(String&) method. Patch is attached.

Such compiler behavior causes floating bugs. I mean this cause must be at "Pick behavior explained" article.

Attachment: gdb_fix.diff
(Size: 1.91KB, Downloaded 250 times)

[Updated on: Fri, 31 January 2014 14:45]

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