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Ddoc
$(D_S Debugging D on Windows,
$(P The Microsoft Windows debugger $(TT $(DMDDIR)\windows\bin\windbg.exe) can be used to
symbolically debug D programs, even though it is a C++ debugger.
Versions of $(TT windbg.exe) other than the one supplied may not work with D.
(Jascha Wetzel's $(LINK2 http://ddbg.mainia.de/releases.html, Ddbg for Windows)
is also available.)
)
$(P To prepare a program for symbolic debugging, compile
with the $(B -gc) switch:
)
$(CONSOLE
dmd myprogram -gc
)
$(P To invoke the debugger on it:
)
$(CONSOLE
windbg myprogram args...
)
$(P
where $(TT args...) are the command line arguments to myprogram.exe.
)
$(P When the debugger comes up, entering the command in the command window:)
$(CONSOLE
g _Dmain
)
$(P will execute the program up until the entry into $(TT main()).
From thence, pressing the $(B F10) key will single step each line
of code.)
$(P Basic Commands:)
$(DL
$(DT F5)
$(DD Go until breakpoint, an exception is thrown, or the end of the program.)
$(DT F7)
$(DD Continue until cursor.)
$(DT F8)
$(DD Single step, stepping into function calls.)
$(DT F10)
$(DD Single step, stepping over function calls.)
)
$(P For more comprehensive information on $(B windbg), consult the
file $(TT $(DMDDIR)\windows\bin\windbg.hlp).
)
$(COMMENT
<h2>Sample Debug Session</h2>
$(P This is a walkthrough of a typical debugging session. Given the program:)
----------
import std.stdio;
class Foo
{
int x;
}
int main()
{
Foo p;
bar(p);
}
void bar(Foo p)
{
abc(p);
}
void abc(Foo p)
{
p.x++;
}
---------
$(P It is compiled and run with the following commands:)
$(CONSOLE
C:\bug>dmd bug -g
\dm\bin\link bug,,,user32+kernel32/co/noi;
C:\bug>bug
Error: Access Violation
C:\bug>
)
$(P It's obviously got a bug, so fire up the debugger with:)
$(CONSOLE
C:\bug>windbg bug.exe
)
$(P and the debugger window comes up:)
<img src="foo.bmp">
$(P Advance to the beginning of $(TT main()) by entering $(TT g _Dmain):)
<img src="windbg2.gif">
$(P now were at the beginning of main(). The upper left black window shows
the console output so far, the middle window shows the current location
and next instruction (the $(TT xor)), The lower right window shows the
current location in the source code, highlighted in yellow.)
$(P In order to run until the exception happens, use the $(TT g) command:)
<img src="windbg3.gif">
$(P The $(TT First chance exception) says an exception was thrown. The
lower right window now shows the line on which the exception happened
highlighted in yellow.)
$(P Now click on the [Window] menu and Select [Calls]:)
<img src="windbg4.gif">
$(P and a window will appear showing the call stack:)
<img src="windbg6.gif">
$(P Clicking on the [Disassembly] command brings up
the Disassembly window where the instruction that faulted is highlighted
in yellow. Clicking on the [Registers] command brings up
the register window, where EAX holds the value 00000000.)
<img src="windbg7.gif">
$(P The trouble is clearly that $(TT p) is $(TT null). Fix it by allocating
an instance for $(TT p):)
----------
import std.stdio;
class Foo
{
int x;
}
int main()
{
Foo p = new Foo; // the fix
bar(p);
}
void bar(Foo p)
{
abc(p);
}
void abc(Foo p)
{
p.x++;
}
---------
$(P and it should now compile and run without error.)
)
)
Macros:
TITLE=windbg Debugger
WIKI=Windbg
CATEGORY_TOOLS=$0