From 36275f7981bdaf919bbc9b51a7c7fae1e192adb3 Mon Sep 17 00:00:00 2001
From: Khem Raj <raj.khem@gmail.com>
Date: Fri, 29 Mar 2013 09:12:56 +0400
Subject: [PATCH 14/46] optional libstdc

gcc-runtime builds libstdc++ separately from gcc-cross-*. Its configure tests using g++
will not run correctly since by default the linker will try to link against libstdc++
which shouldn't exist yet. We need an option to disable -lstdc++
option whilst leaving -lc, -lgcc and other automatic library dependencies added by gcc
driver. This patch adds such an option which only disables the -lstdc++.

A "standard" gcc build uses xgcc and hence avoids this. We should ask upstream how to
do this officially, the likely answer is don't build libstdc++ separately.

RP 29/6/10

Signed-off-by: Khem Raj <raj.khem@gmail.com>

Upstream-Status: Inappropriate [embedded specific]
---
 gcc/c-family/c.opt  |  4 ++++
 gcc/cp/g++spec.c    |  1 +
 gcc/doc/invoke.texi | 32 +++++++++++++++++++++++++++++++-
 gcc/gcc.c           |  1 +
 4 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 4f86876..660da6c 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -1647,6 +1647,10 @@ nostdinc++
 C++ ObjC++
 Do not search standard system include directories for C++.
 
+nostdlib++
+Driver
+Do not link standard C++ runtime library
+
 o
 C ObjC C++ ObjC++ Joined Separate
 ; Documented in common.opt
diff --git a/gcc/cp/g++spec.c b/gcc/cp/g++spec.c
index 03cbde0..3642540 100644
--- a/gcc/cp/g++spec.c
+++ b/gcc/cp/g++spec.c
@@ -137,6 +137,7 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
       switch (decoded_options[i].opt_index)
 	{
 	case OPT_nostdlib:
+	case OPT_nostdlib__:
 	case OPT_nodefaultlibs:
 	  library = -1;
 	  break;
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 8bb49e7..84d68aa 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -207,6 +207,9 @@ in the following sections.
 -fno-weak  -nostdinc++ @gol
 -fvisibility-inlines-hidden @gol
 -fvisibility-ms-compat @gol
+-fvtable-verify=@r{[}std@r{|}preinit@r{|}none@r{]} @gol
+-fvtv-counts -fvtv-debug @gol
+-nostdlib++ @gol
 -fext-numeric-literals @gol
 -Wabi=@var{n}  -Wabi-tag  -Wconversion-null  -Wctor-dtor-privacy @gol
 -Wdelete-non-virtual-dtor -Wliteral-suffix -Wmultiple-inheritance @gol
@@ -470,7 +473,7 @@ Objective-C and Objective-C++ Dialects}.
 -s  -static -static-libgcc -static-libstdc++ @gol
 -static-libasan -static-libtsan -static-liblsan -static-libubsan @gol
 -static-libmpx -static-libmpxwrappers @gol
--shared -shared-libgcc  -symbolic @gol
+-shared -shared-libgcc  -symbolic -nostdlib++ @gol
 -T @var{script}  -Wl,@var{option}  -Xlinker @var{option} @gol
 -u @var{symbol} -z @var{keyword}}
 
@@ -10601,6 +10604,33 @@ library subroutines.
 constructors are called; @pxref{Collect2,,@code{collect2}, gccint,
 GNU Compiler Collection (GCC) Internals}.)
 
+@item -nostdlib++
+@opindex nostdlib++
+Do not use the standard system C++ runtime libraries when linking.
+Only the libraries you specify will be passed to the linker.
+
+@cindex @option{-lgcc}, use with @option{-nostdlib}
+@cindex @option{-nostdlib} and unresolved references
+@cindex unresolved references and @option{-nostdlib}
+@cindex @option{-lgcc}, use with @option{-nodefaultlibs}
+@cindex @option{-nodefaultlibs} and unresolved references
+@cindex unresolved references and @option{-nodefaultlibs}
+One of the standard libraries bypassed by @option{-nostdlib} and
+@option{-nodefaultlibs} is @file{libgcc.a}, a library of internal subroutines
+which GCC uses to overcome shortcomings of particular machines, or special
+needs for some languages.
+(@xref{Interface,,Interfacing to GCC Output,gccint,GNU Compiler
+Collection (GCC) Internals},
+for more discussion of @file{libgcc.a}.)
+In most cases, you need @file{libgcc.a} even when you want to avoid
+other standard libraries.  In other words, when you specify @option{-nostdlib}
+or @option{-nodefaultlibs} you should usually specify @option{-lgcc} as well.
+This ensures that you have no unresolved references to internal GCC
+library subroutines.
+(An example of such an internal subroutine is @code{__main}, used to ensure C++
+constructors are called; @pxref{Collect2,,@code{collect2}, gccint,
+GNU Compiler Collection (GCC) Internals}.)
+
 @item -pie
 @opindex pie
 Produce a position independent executable on targets that support it.
diff --git a/gcc/gcc.c b/gcc/gcc.c
index 4cfef7f..da0b482 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -1028,6 +1028,7 @@ proper position among the other output files.  */
     %(mflib) " STACK_SPLIT_SPEC "\
     %{fprofile-arcs|fprofile-generate*|coverage:-lgcov} " SANITIZER_SPEC " \
     %{!nostdlib:%{!nodefaultlibs:%(link_ssp) %(link_gcc_c_sequence)}}\
+    %{!nostdlib++:}\
     %{!nostdlib:%{!nostartfiles:%E}} %{T*}  \n%(post_link) }}}}}}"
 #endif
 
-- 
2.8.2