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I've been updating my Mac toolchain in order to take advantage of C++11 features and eventually get pretty-print debugging of STL data structures. I used Homebrew to build the gcc 4.7.2 compiler. I've been able to recompile the source of my current project using this new compiler. However all versions of gdb that I've tried have various problems when setting breakpoints, viewing source code or viewing local variables.

The version of gdb that I believe is installed as part of the Xcode command-line tools, version 6.3.50, has trouble displaying various template-based variables. I've also built and tried to use several other gdb versions (7.3.1, 7.4.1 & 7.5.1), but each gdb version has problems that make it difficult to impossible to set breakpoints, view source code and view variables. Specifically, these gdb versions don't know the source file or line number of functions defined in header files, breakpoints can't be set in these header-file functions, and many local variables have been "optimized out".

Has anybody else experienced these problems, and if so have you been able to resolve them? Which versions should I be using in my toolchain in order to avoid these problems?

For the record, my development is on a recent MBP running the latest Mountain Lion updates. My IDE is Eclipse Juno with CDT version 8.1.1. And, yes, I've code signed all versions of gdb that I've built and attempted to use.

Thanks for any input,

Bob

ildjarn
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neobobkrause
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1 Answers1

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many local variables have been "optimized out".

Is this happening while debugging optimized code? If so, that is expected. You may not have seen this happening before, because older GCC didn't quite optimize that much.

To fix: build your to-be-debugged code with -g -O0 flags.

Employed Russian
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  • I'm compiling with -g3 and -O0, and yet variables like 'this' pointers are shown as optimized out by gdb even in those methods that reference data members. But another big challenge is that gdb doesn't appear to have source file and line number information for methods defined in header files. So I can't set breakpoints or step though execution. – neobobkrause Dec 12 '12 at 19:04
  • Or better yet, `gcc -ggdb3 -O0` – Fabio A. Correa Oct 17 '14 at 23:51