Re: [Windows/RFA/commit] Deprecate windows-specific dll-symbols command and aliases

[Joel Brobecker <brobecker@adacore.com>]

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Hi Eli,

Attached is the new version of the patch, with the GDB manual now
simply stating that the commands are deprecated instead of removing
their documentation. Can you tell me if the changes look OK? I still
kept the removal of the dubious recommendation of loading the DLL
statements by hand, as I don't think we should be advertising that
practice.

gdb/ChangeLog:

        * windows-nat.c (_initialize_windows_nat): Deprecate the
        "dll-symbols" command.  Turn the "add-shared-symbol-files"
        and "assf" aliases into commands, and deprecate them as well.
        * NEWS: Add entry explaining that "dll-symbols" and its two
        aliases are now deprecated.

gdb/doc/ChangeLog:

        * gdb.texinfo (Files): Document "add-shared-symbol-files"
        and "assf" as being deprecated.
        (Cygwin Native): Likewise for "dll-symbols".
        (Non-debug DLL Symbols): Remove reference to "dll-symbols"
        as a way to force the loading of symbols from a DLL.

Thank you,
-- 
Joel

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From b89a5f03be0fd9e70506f08f499051f2bf8e2d3d Mon Sep 17 00:00:00 2001
From: Joel Brobecker <brobecker@adacore.com>
Date: Fri, 31 Jan 2014 04:22:53 -0500
Subject: [PATCH] Deprecate windows-specific dll-symbols command and aliases

The "dll-symbols" command, specific to native Windows platforms,
gives the impression that the symbols were not loaded, first
because it completes silently, and second because the "info shared"
output does not get updated after the command completes:

    (gdb) dll-symbols C:\WINDOWS\syswow64\rpcrt4.dll
    (gdb) info shared
    From        To          Syms Read   Shared Object Library
    [...]
    0x77e51000  0x77ee2554  No          C:\WINDOWS\system32\rpcrt4.dll

(we exected the "Syms Read" column to read "Yes").

As far as I can tell, the symbols actually do get loaded, but completely
independently from the solib framework, which explains the silent
loading and the fact that the "Syms Read" column does not get updated.
See windows-nat.c::safe_symbol_file_add_stub, which calls symbol_file_add
instead of calling solib_add.

But, aside from the fact that the "Syms Read" status does not get
updated, I also noticed that it does not take into account the DLL's
actual load address when loading its symbols. As a result, I believe
that we get it wrong if the DLL does not get loaded at the prefered
address.

Rather than trying to fix this command, there does not seem to be
a reason other than historical for having Windows-specific commands
which essentially re-implements the "sharedlibrary" command. The
command interface is slightly different (the latter takes a regexp
rather than a plain filename), but it should be just as easy to use
the "sharedlibrary" command, or its "share" alias, as usisng the
"dll-symbols" command. For instance:

    (gdb) share rpcrt4.dll
    Reading symbols from C:\WINDOWS\system32\rpcrt4.dll...(no debugging symbols found)...done.
    Loaded symbols for C:\WINDOWS\system32\rpcrt4.dll
    (gdb) info shared
    From        To          Syms Read   Shared Object Library
    [...]
    0x77e51000  0x77ee2554  Yes (*)     C:\WINDOWS\system32\rpcrt4.dll

This patch therefore deprecates the "dll-symbols" command, as well
as its two aliases "add-shared-symbol-files" and "assf", with a view
of deleting them as soon as the 7.8 branch gets cut.

gdb/ChangeLog:

	* windows-nat.c (_initialize_windows_nat): Deprecate the
	"dll-symbols" command.  Turn the "add-shared-symbol-files"
	and "assf" aliases into commands, and deprecate them as well.
	* NEWS: Add entry explaining that "dll-symbols" and its two
	aliases are now deprecated.

gdb/doc/ChangeLog:

        * gdb.texinfo (Files): Document "add-shared-symbol-files"
        and "assf" as being deprecated.
        (Cygwin Native): Likewise for "dll-symbols".
        (Non-debug DLL Symbols): Remove reference to "dll-symbols"
        as a way to force the loading of symbols from a DLL.
---
 gdb/NEWS            |  4 ++++
 gdb/doc/gdb.texinfo | 14 +++++++-------
 gdb/windows-nat.c   | 13 +++++++++----
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index b54a414..eeb2f94 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -85,6 +85,10 @@ qXfer:btrace:read's annex
 * New targets
 PowerPC64 GNU/Linux little-endian	powerpc64le-*-linux*
 
+* The "dll-symbols" command, and its two aliases ("add-shared-symbol-files"
+  and "assf"), have been deprecated.  Use the "sharedlibrary" command, or
+  its alias "share", instead.
+
 *** Changes in GDB 7.7
 
 * Improved support for process record-replay and reverse debugging on
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 7dc1564..de5ac63 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -16923,6 +16923,9 @@ For this command to work, you must have used @code{symbol-file} or
 @kindex assf
 @item add-shared-symbol-files @var{library-file}
 @itemx assf @var{library-file}
+This command is deprecated and will be removed in future versions
+of @value{GDBN}.  Use the @code{sharedlibrary} command instead.
+
 The @code{add-shared-symbol-files} command can currently be used only
 in the Cygwin build of @value{GDBN} on MS-Windows OS, where it is an
 alias for the @code{dll-symbols} command (@pxref{Cygwin Native}).
@@ -19901,6 +19904,9 @@ This is a Cygwin-specific alias of @code{info shared}.
 
 @kindex dll-symbols
 @item dll-symbols
+This command is deprecated and will be removed in future versions
+of @value{GDBN}.  Use the @code{sharedlibrary} command instead.
+
 This command loads symbols from a dll similarly to
 add-sym command but without the need to specify a base address.
 
@@ -19998,13 +20004,7 @@ describes working with such symbols, known internally to @value{GDBN} as
 Note that before the debugged program has started execution, no DLLs
 will have been loaded.  The easiest way around this problem is simply to
 start the program --- either by setting a breakpoint or letting the
-program run once to completion.  It is also possible to force
-@value{GDBN} to load a particular DLL before starting the executable ---
-see the shared library information in @ref{Files}, or the
-@code{dll-symbols} command in @ref{Cygwin Native}.  Currently,
-explicitly loading symbols from a DLL with no debugging information will
-cause the symbol names to be duplicated in @value{GDBN}'s lookup table,
-which may adversely affect symbol lookup performance.
+program run once to completion.
 
 @subsubsection DLL Name Prefixes
 
diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index 9212adf..3dbd3c2 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -2671,12 +2671,17 @@ _initialize_windows_nat (void)
   c = add_com ("dll-symbols", class_files, dll_symbol_command,
 	       _("Load dll library symbols from FILE."));
   set_cmd_completer (c, filename_completer);
+  deprecate_cmd (c, "sharedlibrary");
 
-  add_com_alias ("sharedlibrary", "dll-symbols", class_alias, 1);
-
-  add_com_alias ("add-shared-symbol-files", "dll-symbols", class_alias, 1);
+  c = add_com ("add-shared-symbol-files", class_files, dll_symbol_command,
+	       _("Load dll library symbols from FILE."));
+  set_cmd_completer (c, filename_completer);
+  deprecate_cmd (c, "sharedlibrary");
 
-  add_com_alias ("assf", "dll-symbols", class_alias, 1);
+  c = add_com ("assf", class_files, dll_symbol_command,
+	       _("Load dll library symbols from FILE."));
+  set_cmd_completer (c, filename_completer);
+  deprecate_cmd (c, "sharedlibrary");
 
 #ifdef __CYGWIN__
   add_setshow_boolean_cmd ("shell", class_support, &useshell, _("\
-- 
1.8.3.2