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I am building something on HPUX. Code works fine in Sun/Linux/AIX.

But on HPUX it complains on 

[sshexec] /usr/ccs/bin/ld: Unsatisfied symbols:
[sshexec]    globalVar (first referenced in blah.o)

Once again code works in Release but not in Debug. All it does it uses global variable defined in some other file

extern globPck globalVar;

globPck is class that cointains some global stuff.

I am more interested in ideas what could be the reason for this to work in Release but not in Debug.

I looked over .i files (precompiled header file generated with -E) And it seems defined in same way.

I am guessing something that is hit in Release code path fixes it but I am here to hear if yall have some ideas.

j0k
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grobartn
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2 Answers2

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The first thing to do when the linker complains that something isn't defined is to go find for yourself where that thing is defined. If you can't find it, then don't expect the linker to find it, either.

What you have shown is a declaration, not a definition. A definition will not have the extern keyword. There should be a definition in exactly one .cpp file in your project, not a header.

Once you've found the definition, then you can start working on why the linker doesn't see it. Maybe it's only defined when certain symbols are present, such as DEBUG or NDEBUG.

If there is no definition, then maybe all uses of it get removed during release compilation (perhaps because all uses occur in assert statements that the compiler omits), so the missing definition isn't noticed in release mode.

Rob Kennedy
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  • it is quite weird because in release mode that symbol is not in .o object (when you do nm blah.o | grep globalVar. It only shows in Debug and I looked and nowhere does it have #if DEBUG or what not... – grobartn Jan 06 '11 at 21:09
  • In that situation, I'd do a sanity check: Intentionally add a syntax error next to the place where you believe `globalVar` gets defined. Compile in release mode and confirm (by getting a compiler error) that the compiler is seeing that line of code. If you get no error, then either the compiler isn't compiling the file you thought it was, or you need to expand your search for the `#ifdef` that's blocking access to your code. – Rob Kennedy Jan 06 '11 at 21:49
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The HPUX Compiler loves to "Optimize away" Constructor calls to global classes if the classes are only accessed indirectly from the main path of execution. Try adding a simple printf() with the value of the variable in your main thread somewhere an see if the problem dissappears.

Bruce Ricker
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  • Welcome on SO. Please take care of punctuation in order to make your answer easier to read and understand. – Tarec May 14 '14 at 13:53