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From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
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From: Kevin Buettner <kevinb@redhat.com>
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Date: Wed, 3 May 2023 11:28:24 -0700
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Subject: gdb-rhbz2192105-ftbs-dangling-pointer
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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;; Backport upstream patch fixing a "dangling pointer" build problem
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;; first seen when building with GCC 13.1.1 20230426 (Red Hat ;; 13.1.1-1).
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Pass const frame_info_ptr reference for skip_[language_]trampoline
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g++ 13.1.1 produces a -Werror=dangling-pointer=
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In file included from ../../binutils-gdb/gdb/frame.h:75,
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                 from ../../binutils-gdb/gdb/symtab.h:40,
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                 from ../../binutils-gdb/gdb/language.c:33:
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In member function ‘void intrusive_list<T, AsNode>::push_empty(T&) [with T = frame_info_ptr; AsNode = intrusive_base_node<frame_info_ptr>]’,
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    inlined from ‘void intrusive_list<T, AsNode>::push_back(reference) [with T = frame_info_ptr; AsNode = intrusive_base_node<frame_info_ptr>]’ at gdbsupport/intrusive_list.h:332:24,
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    inlined from ‘frame_info_ptr::frame_info_ptr(const frame_info_ptr&)’ at gdb/frame.h:241:26,
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    inlined from ‘CORE_ADDR skip_language_trampoline(frame_info_ptr, CORE_ADDR)’ at gdb/language.c:530:49:
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gdbsupport/intrusive_list.h:415:12: error: storing the address of local variable ‘<anonymous>’ in ‘frame_info_ptr::frame_list.intrusive_list<frame_info_ptr>::m_back’ [-Werror=dangling-pointer=]
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  415 |     m_back = &ele;;
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      |     ~~~~~~~^~~~~~~
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gdb/language.c: In function ‘CORE_ADDR skip_language_trampoline(frame_info_ptr, CORE_ADDR)’:
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gdb/language.c:530:49: note: ‘<anonymous>’ declared here
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  530 |       CORE_ADDR real_pc = lang->skip_trampoline (frame, pc);
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      |                           ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
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gdb/frame.h:359:41: note: ‘frame_info_ptr::frame_list’ declared here
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  359 |   static intrusive_list<frame_info_ptr> frame_list;
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      |                                         ^~~~~~~~~~
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Each new frame_info_ptr is being pushed on a static frame list and g++
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cannot see why that is safe in case the frame_info_ptr is created and
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destroyed immediately when passed as value.
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It isn't clear why only in this one place g++ sees the issue (probably
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because it can inline enough code in this specific case).
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Since passing the frame_info_ptr as const reference is cheaper, use
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that as workaround for this warning.
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PR build/30413
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Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30413
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Tested-by: Kevin Buettner <kevinb@redhat.com>
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Reviewed-by: Kevin Buettner <kevinb@redhat.com>
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Reviewed-by: Tom Tromey <tom@tromey.com>
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diff --git a/gdb/c-lang.c b/gdb/c-lang.c
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--- a/gdb/c-lang.c
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+++ b/gdb/c-lang.c
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@@ -1003,7 +1003,7 @@ class cplus_language : public language_defn
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   /* See language.h.  */
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-  CORE_ADDR skip_trampoline (frame_info_ptr fi,
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+  CORE_ADDR skip_trampoline (const frame_info_ptr &fi,
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 			     CORE_ADDR pc) const override
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   {
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     return cplus_skip_trampoline (fi, pc);
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diff --git a/gdb/language.c b/gdb/language.c
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--- a/gdb/language.c
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+++ b/gdb/language.c
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@@ -528,7 +528,7 @@ add_set_language_command ()
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    Return the result from the first that returns non-zero, or 0 if all
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    `fail'.  */
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 CORE_ADDR 
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-skip_language_trampoline (frame_info_ptr frame, CORE_ADDR pc)
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+skip_language_trampoline (const frame_info_ptr &frame, CORE_ADDR pc)
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 {
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   for (const auto &lang : language_defn::languages)
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     {
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diff --git a/gdb/language.h b/gdb/language.h
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--- a/gdb/language.h
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+++ b/gdb/language.h
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@@ -471,7 +471,7 @@ struct language_defn
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      If that PC falls in a trampoline belonging to this language, return
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      the address of the first pc in the real function, or 0 if it isn't a
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      language tramp for this language.  */
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-  virtual CORE_ADDR skip_trampoline (frame_info_ptr fi, CORE_ADDR pc) const
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+  virtual CORE_ADDR skip_trampoline (const frame_info_ptr &fi, CORE_ADDR pc) const
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   {
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     return (CORE_ADDR) 0;
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   }
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@@ -789,7 +789,7 @@ extern const char *language_str (enum language);
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 /* Check for a language-specific trampoline.  */
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-extern CORE_ADDR skip_language_trampoline (frame_info_ptr, CORE_ADDR pc);
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+extern CORE_ADDR skip_language_trampoline (const frame_info_ptr &, CORE_ADDR pc);
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 /* Return demangled language symbol, or NULL.  */
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 extern gdb::unique_xmalloc_ptr<char> language_demangle
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diff --git a/gdb/objc-lang.c b/gdb/objc-lang.c
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--- a/gdb/objc-lang.c
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+++ b/gdb/objc-lang.c
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@@ -282,7 +282,7 @@ class objc_language : public language_defn
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   /* See language.h.  */
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-  CORE_ADDR skip_trampoline (frame_info_ptr frame,
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+  CORE_ADDR skip_trampoline (const frame_info_ptr &frame,
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 			     CORE_ADDR stop_pc) const override
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   {
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     struct gdbarch *gdbarch = get_frame_arch (frame);