GDB: debugger won't step into code / breakpoints won't break
lazarus / 12-Debugger

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CCRDude · 2017-06-22 14:09

I'm currently trying out some debugger code outside the IDE (will be
added as a package later), and have problems with reaching certain
code.

Situation: a FPCUnit console runner program. If I try to go through
the whole program in the IDE pressing F7, I cannot reach my test code
(probably because it's called from the test suite, which is in a
package, which has no debugging information). If I set a break point
within my test methods, I can reach them.

Experienced:
1. using a self created instance of TGDBMIDebugger, I can stepinto the
whole program as well, but would not reach my test methods (as above
with Lazarus itself).
2. using gdb on the console, I can set breakpoints on the test
methods, and this way, gdb will step into this code.
3. using a self created instance of TGDBMIDebugger, the breakpoints I
set are not working.

Expected:
Breakpoints to break execution, even if stepinto would otherwise skip
it. I log the OnCurrent event to see which lines are reached, and
those of the test methods are not. OnBreakpointHit is not triggered
either.

Some very simple code:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TCodeCoverageDebugger.Go(AFilename: string);var   i: integer;begin 
 FDebugger.Free;   FDebugger := CreateDebugger; 
 FLineProtocol.Clear; 
 FDebugger.BreakPoints.Add('c:\Development\Projects\CodingTools\laz-
codecoverage-helper\source\CodeCoverage.GDB.TestCase.pas', 65); 
 FDebugger.BreakPoints.Add('c:\Development\Projects\CodingTools\laz-
codecoverage-helper\source\CodeCoverage.GDB.TestCase.pas', i);   FDebu
gger.BreakPoints.Add('TCODECOVERAGEGDBTESTCASE__TESTLISTALLUNITFILENAM
ES');   FDebugger.Init;   try      FDebugger.FileName := AFilename;  
  FDebugger.WorkingDir := ExtractFilePath(AFilename);      repeat    
   FDebugger.StepInto;      until (FDebugger.State in [dsStop]); 
 finally      FDebugger.Done;   end;end;      
This is the debugger unit from which the above code is from, the
TestDebugger project with the TestDebuggerForm form unit is there as
well.

(it uses a slightly modified version of GDBMIDebugger.pas, where I
added support for breakpoints by name, but only because the line based
approach did not work before)

Has anyone enough direct experience with the debugger to see what I'm
missing?

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CCRDude · 2017-06-23 07:34

I'm getting nearer:

QuoteOutput: (gdb)
Output: <info line "c:\Development\Projects\CodingTools\laz-
codecoverage-helper\source\CodeCoverage.GDB.TestCase.pas":97>
Output: &"info line \"c:\\Development\\Projects\\CodingTools\\laz-
codecoverage-helper\\source\\CodeCoverage.GDB.TestCase.pas\":97\n"
Output: ~"Line 97 of \"CodeCoverage.GDB.TestCase.pas\" is at address
0x423210 <TCODECOVERAGEGDBTESTCASE__TESTGETUNITFULLFILENAME> but
contains no code.\n"
Output: ^done
Output: (gdb)
Output: <-break-insert  "\"c:/Development/Projects/CodingTools/laz-
codecoverage-helper/source/CodeCoverage.GDB.TestCase.pas\":97">
Output: ^done,bkpt={number="9",type="breakpoint",disp="keep",enabled="
y",addr="0x0042321e",func="TCODECOVERAGEGDBTESTCASE__TESTGETUNITFULLFI
LENAME",file="CodeCoverage.GDB.TestCase.pas",fullname="C:\\Development
\\Projects\\CodingTools\\laz-codecoverage-
helper\\source\\CodeCoverage.GDB.TestCase.pas",line="97",thread-
groups=["i1"],times="0",original-
location="c:/Development/Projects/CodingTools/laz-codecoverage-
helper/source/CodeCoverage.GDB.TestCase.pas:97"}
Output: (gdb)
Output: <-break-disable 9>
Output: ^done
Output: (gdb)

Direct "break" command at the console seems to behave differently than
the -break-insert of the MI interface; it does not complain about the
line not containing code.

Quote(gdb) break c:\Development\Projects\CodingTools\laz-codecoverage-
helper\source\CodeCoverage.GDB.TestCase.pas:65
Breakpoint 1 at 0x42306e: file CodeCoverage.GDB.TestCase.pas, line 65.
But even if I choose a line containing code, and set Enabled to true,
-break-disable is called on my custom breakpoints... will need to dive
deeper into the debugger units code.

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CCRDude · 2017-06-23 08:32

Problem found; breakpoints get disabled by GDBMIDebugger when created;
setting Enabled only works after the process has started (which for
gdb is an unnecessary restriction imho, based on my experience with
gdb at the console).