Re: [RFA/windows] Spurious "dll not found" error messages on x64-windows.

[Joel Brobecker <brobecker@adacore.com>]

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> Sorry but, I don't think this right.  What's the point of issuing the
> error after inferior startup?  I think it's only during startup that
> something like this would be useful.
> 
> I think making the error a complaint makes more sense.

Sure. I am not sure when DLLs are unloaded most... I was thinking
more about the case where a user does a LoadLibrary/FreeLibrary.

Regardless, here is a version that transforms the error into a complaint.
So far, complaints appears to be used only for symbol file events.
It's a tiny bit of a strech to include our complaint in that category,
but I think that creating a different category for that might be
a bit overkill. I don't mind doing so, however. I chose the simpler
approach for now, which gives us the following complaint when they
are activated:

    [New Thread 94404.0x222a8]
    During symbol reading, dll starting at 0x77a60000 not found..
    During symbol reading, dll starting at 0x77650000 not found..
    [...]

The "During symbol reading" is where the complaint category comes
in play.

Note that the module description in complaints.h says:

    Definitions for complaint handling during symbol reading in GDB.

But I don't see why this couldn't be used for other purposes (and
hence why we couldn't create new categories if necessary).

gdb/ChangeLog:

        * windows-nat.c: Add include of complaints.h.
        (handle_unload_dll): Change dll-not-found error into a complaint.

Tested on x86_64-windows with an x86-windows toolchain.

-- 
Joel

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--- windows-nat.c.orig	2010-02-11 12:09:23.911442400 +0100
+++ windows-nat.c	2010-02-11 11:22:29.060598600 +0100
@@ -64,6 +64,7 @@
 #include "windows-tdep.h"
 #include "windows-nat.h"
 #include "i386-nat.h"
+#include "complaints.h"
 
 #define AdjustTokenPrivileges		dyn_AdjustTokenPrivileges
 #define DebugActiveProcessStop		dyn_DebugActiveProcessStop
@@ -783,8 +784,15 @@ handle_unload_dll (void *dummy)
 	return 1;
       }
 
-  error (_("Error: dll starting at %s not found."),
-	   host_address_to_string (lpBaseOfDll));
+  /* We did not find any DLL that was previously loaded at this address,
+     so register a complaint.  We do not report an error, because we have
+     observed that this may be happening under some circumstances.  For
+     instance, running 32bit applications on x64 Windows causes us to receive
+     4 mysterious UNLOAD_DLL_DEBUG_EVENTs during the startup phase (these
+     events are apparently caused by the WOW layer, the interface between
+     32bit and 64bit worlds).  */
+  complaint (&symfile_complaints, _("dll starting at %s not found."),
+	     host_address_to_string (lpBaseOfDll));
 
   return 0;
 }