Re: [MACTCL] MacOS Debugging setup

[Phillip B. <phi...@um...>]

Thanks Kevin,

I am pretty familiar with gdb and debugging Tcl in a Linux environment.
The gdb-lldb guide will be useful, but that isn’t where I am hung up.

I am hung up on these two questions:

What configure and build options will give me source level debugging on a
MacOS tclsh build?

Where is the debug version of tclsh after I do that build?

Do I need to do anything special to avoid MacOS security (I.e. signing
things)?

Phil



On Thu, Oct 23, 2025 at 4:22 PM Kevin Walzer <kw...@co...> wrote:

> Debugging a Tcl extension written in C using gdb
> <https://wiki.tcl-lang.org/page/Debugging+a+Tcl+extension+written+in+C+using+gdb?R=0>
> wiki.tcl-lang.org
> <https://wiki.tcl-lang.org/page/Debugging+a+Tcl+extension+written+in+C+using+gdb?R=0>
> [image: favicon.ico]
> <https://wiki.tcl-lang.org/page/Debugging+a+Tcl+extension+written+in+C+using+gdb?R=0>
> <https://wiki.tcl-lang.org/page/Debugging+a+Tcl+extension+written+in+C+using+gdb?R=0>
>
> This is a guide to using gdb with Tcl.
>
> GDB and LLDB Command Examples
> <https://developer.apple.com/library/archive/documentation/IDEs/Conceptual/gdb_to_lldb_transition_guide/document/lldb-command-examples.html>
> developer.apple.com
> <https://developer.apple.com/library/archive/documentation/IDEs/Conceptual/gdb_to_lldb_transition_guide/document/lldb-command-examples.html>
> [image: apple-touch-icon-precomposed.png]
> <https://developer.apple.com/library/archive/documentation/IDEs/Conceptual/gdb_to_lldb_transition_guide/document/lldb-command-examples.html>
> <https://developer.apple.com/library/archive/documentation/IDEs/Conceptual/gdb_to_lldb_transition_guide/document/lldb-command-examples.html>
>
> This is a gdb-lldb translation guide.
>
> On Oct 23, 2025, at 6:43 PM, Phillip Brooks <phi...@um...> wrote:
>
> 
>
> Can anyone point me toward a guide to running lldb on a built Tcl
> executable on MacOS 26 Arm64?  I found:
>
> https://wiki.tcl-lang.org/page/Tcl+on+MacOS
>
> on the wiki, but it seems more interested in wish than in Tcl, and also in
> exercising the full MacOS App mechanism and running Wish.app.  There isn't
> much there about running the debugger and even less about tclsh.  I have
> successfully built tclsh, and can invoke it under lldb, set breakpoints,
> run etc. but I seem unable to get a debug version of the file that I am
> trying to look at (tclParse.c).  I can see source code around the call to
> Tcl_Main, but not at lower levels of the stack.  When I stop, say in
> Tcl_ParseVarName, I just see assembly code.
>
> Can you describe how to build, invoke lldb, set a breakpoint at
> Tcl_ParseVarName and then have the debugger show source code for
> Tcl_ParseVarName?
>
> Here is a detailed runthrough of what I last tried:
>
> I used the make command:
>
> $ CONFIGURE_ARGS="--enable-symbols" make -f GNUmakefile
>
>  inside of the macosx directory, then ran lldb:
>
> $ lldb ../../build/tcl/Development//usr/local/bin/Development/tclsh
>
> I ran that tclsh in another shell window and I used the attach <pid>
> command to attach to my running tclsh (I want to be able to type into Tcl
> and debug from another window at the same time), though I get the same
> result when I just use the run command from inside lldb.
>
> Typed "b Tcl_ParseVarName" and successfully set the breakpoint.
>
> Typed continue, but when it stops in Tcl_ParseVarName, I see only assembly
> code, no source.  If I type list, I see source code, but it is only for the
> call to Tcl_Main.  I can't go down the stack without diving into assembly
> code.  I am thinking that I have only partial debug code for some reason,
> but I don't know enough about how the MacOS build works to know what is
> where and how it got there.  It seems that things are built a couple times
> by default.
>
> I am running on MacOS 26 - newly installed, and have never tried running a
> debugger on MacOS before (my previous experience is all on Linux).  I am
> also trying to build something close to the tip of Tcl 9.1 - i.e. the main
> branch.  I am a complete newbie concerning things like codesigning etc.
>
> Phil
>
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