On 3 Nov, Don Lewis wrote:
> For much of our history, until fairly recently, the versions of gcc that
> we used defaulted to -std=gnu++98 when compiiling C++ code.
>
> When FreeBSD on i386 and amd64 switched from gcc to clang, it also
> defaulted to -std=gnu++98. Clang has been C++11 compliant from version
> 3.3 onwards. Around the time of the switch, I added the
> -DHAVE_STL_INCLUDE_PATH compiler flag so that clang would use it's own
> STL include files instead of the boost TR1 includes. Clang was
> perfectly happy using its own STL include files even though they were
> not part of C++98, only C++11.
>
> Later on, when clang 6 changed the default to gnu++14, the build
> generated tons warning and some number of errors. To work around this,
> I added the -std=gnu++98 compiler flag to force the old mode.
>
> FreeBSD on powerpc still uses gcc and it recently came to my attention
> that the build was broken there. The FreeBSD port of AOO to powerpc
> does not use -DHAVE_STL_INCLUDE_PATH, so it was falling back to the
> boost TR1 headers. The FreeBSD port uses the system boost, and recent
> versions of boost have dropped TR1 support. To work around that, I
> tried enabling -DHAVE_STL_INCLUDE_PATH to use the gcc C++ headers. This
> failed badly because the gcc STL headers check to see if the compilation
> mode is C++11 or better and immediately error out of this is not the
> case. Switching the compilation mode to c++11 results in the warning
> and error spew mentioned above. I tried modifying the stlport headers
> to include the gcc TR1 headers in gnu++98 mode. That worked better, but
> I still got some mysterious C++ errors that I was not able to figure
> out. My next attempt will be to try the boost non-TR1 headers.
>
> Turning to Linux as a stepping stone, I've notice the build warning
> spewage on recent Linux distributions, such as Debian 9, that have newer
> versions of gcc. By using the patch below, I was able to reduce the
> size of the build log for trunk from 1354815 lines to 359998 lines. I
> think the extra compiler defines are required because the compiler
> detection code in our bundled version of boost is too old to figure out
> what to do with new gcc in gnu++98 mode.
>
> One of the largest contributors to the warnings is std::auto_ptr. This
> is deprecated in C++11 and is totally removed in C++17. The new way is
> to use std::unique_ptr, but that wasn't available before C++11. We
> can't fix our code for this until we are totally off the old toolchains,
> which means after we have abandoned CentOS 6 and earlier as well as
> Visual Studio earlier than 2015.
>
> Once our code has been converted to C++11, then I think we might be able
> to deorbit the boost and stlport modules and just use the compiler
> includes directly.
>
> diff --git a/main/solenv/gbuild/platform/linux.mk
> b/main/solenv/gbuild/platform/linux.mk
> index 3f35f2a3ce..0ffaf1a84f 100644
> --- a/main/solenv/gbuild/platform/linux.mk
> +++ b/main/solenv/gbuild/platform/linux.mk
> @@ -89,6 +89,10 @@ gb_CXXFLAGS := \
> -fuse-cxa-atexit \
> -fvisibility-inlines-hidden \
> -fvisibility=hidden \
> + -std=gnu++98 \
> + -DBOOST_NO_CXX11_VARIADIC_TEMPLATES \
> + -DBOOST_NO_CXX11_RVALUE_REFERENCES \
> + -DBOOST_NO_CXX11_STATIC_ASSERT \
> -pipe \
>
> ifneq ($(EXTERNAL_WARNINGS_NOT_ERRORS),TRUE)
> diff --git a/main/solenv/inc/unxlng.mk b/main/solenv/inc/unxlng.mk
> index afaa50a0e5..060ee5976c 100644
> --- a/main/solenv/inc/unxlng.mk
> +++ b/main/solenv/inc/unxlng.mk
> @@ -77,7 +77,7 @@ CFLAGSENABLESYMBOLS=-g # was temporarily commented out,
> reenabled before Beta
> .ENDIF
>
> # flags for the C++ Compiler
> -CFLAGSCC= -pipe $(ARCH_FLAGS)
> +CFLAGSCC= -pipe $(ARCH_FLAGS) -std=gnu++98
> -DBOOST_NO_CXX11_VARIADIC_TEMPLATES -DBOOST_NO_CXX11_RVALUE_REFERENCES
> -DBOOST_NO_CXX11_STATIC_ASSERT
> # Flags for enabling exception handling
> .IF "$(COM)"=="CLANG"
> CFLAGSEXCEPTIONS=-fexceptions
If I fix the compiler feature detection code in boost, then the changes
needed to always build in gnu++98 mode on Linux are pretty trivial:
diff --git a/main/boost/boost_1_55_0.patch b/main/boost/boost_1_55_0.patch
index 6cec7bb358..df9b8ec8e0 100644
--- a/main/boost/boost_1_55_0.patch
+++ b/main/boost/boost_1_55_0.patch
@@ -328,22 +328,34 @@ diff -ur
misc/boost_1_55_0/boost/unordered/detail/unique.hpp misc/build/boost_1_
////////////////////////////////////////////////////////////////////////
diff -ur misc/boost_1_55_0/boost/config/compiler/gcc.hpp
misc/build/boost_1_55_0/boost/config/compiler/gcc.hpp
--- misc/boost_1_55_0/boost/config/compiler/gcc.hpp 2013-09-17
09:55:51.000000000 -0700
-+++ misc/build/boost_1_55_0/boost/config/compiler/gcc.hpp 2016-09-02
19:15:48.775411000 -0700
-@@ -137,7 +137,7 @@
++++ misc/build/boost_1_55_0/boost/config/compiler/gcc.hpp 2019-11-04
09:59:20.741944674 -0800
+@@ -137,14 +137,18 @@
// C++0x features in 4.3.n and later
//
-#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 2)) &&
defined(__GXX_EXPERIMENTAL_CXX0X__)
-+#if ((__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 2)) &&
defined(__GXX_EXPERIMENTAL_CXX0X__)) || (__GNUC__ > 6) || (__GNUC__ == 6 &&
__GNUC_MINOR__ > 0)
++#if ((__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 2)) &&
defined(__GXX_EXPERIMENTAL_CXX0X__)) || (__cplusplus >= 201103L)
// C++0x features are only enabled when -std=c++0x or -std=gnu++0x are
// passed on the command line, which in turn defines
// __GXX_EXPERIMENTAL_CXX0X__.
-@@ -153,7 +153,7 @@
+ # define BOOST_HAS_DECLTYPE
+ # define BOOST_HAS_RVALUE_REFS
+ # define BOOST_HAS_STATIC_ASSERT
+-# define BOOST_HAS_VARIADIC_TMPL
++# if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 4))
++# define BOOST_HAS_VARIADIC_TMPL
++# else
++# define BOOST_NO_CXX11_VARIADIC_TEMPLATES
++# endif
+ #else
+ # define BOOST_NO_CXX11_DECLTYPE
+ # define BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS
+@@ -153,7 +157,7 @@
// Variadic templates compiler:
// http://www.generic-programming.org/~dgregor/cpp/variadic-templates.html
-# if defined(__VARIADIC_TEMPLATES) || (__GNUC__ > 4) || ((__GNUC__ == 4) &&
(__GNUC_MINOR__ >= 4) && defined(__GXX_EXPERIMENTAL_CXX0X__))
-+# if defined(__VARIADIC_TEMPLATES) || ((__GNUC__ > 4 || (__GNUC__ == 4 &&
__GNUC_MINOR__ > 2)) && defined(__GXX_EXPERIMENTAL_CXX0X__)) || (__GNUC__ > 6)
|| (__GNUC__ == 6 && __GNUC_MINOR__ > 0)
++# if defined(__VARIADIC_TEMPLATES)
# define BOOST_HAS_VARIADIC_TMPL
# else
# define BOOST_NO_CXX11_VARIADIC_TEMPLATES
diff --git a/main/solenv/gbuild/platform/linux.mk
b/main/solenv/gbuild/platform/linux.mk
index 3f35f2a3ce..02b8830a39 100644
--- a/main/solenv/gbuild/platform/linux.mk
+++ b/main/solenv/gbuild/platform/linux.mk
@@ -89,6 +89,7 @@ gb_CXXFLAGS := \
-fuse-cxa-atexit \
-fvisibility-inlines-hidden \
-fvisibility=hidden \
+ -std=gnu++98 \
-pipe \
ifneq ($(EXTERNAL_WARNINGS_NOT_ERRORS),TRUE)
diff --git a/main/solenv/inc/unxlng.mk b/main/solenv/inc/unxlng.mk
index afaa50a0e5..32b88bc91d 100644
--- a/main/solenv/inc/unxlng.mk
+++ b/main/solenv/inc/unxlng.mk
@@ -77,7 +77,7 @@ CFLAGSENABLESYMBOLS=-g # was temporarily commented out,
reenabled before Beta
.ENDIF
# flags for the C++ Compiler
-CFLAGSCC= -pipe $(ARCH_FLAGS)
+CFLAGSCC= -pipe $(ARCH_FLAGS) -std=gnu++98
# Flags for enabling exception handling
.IF "$(COM)"=="CLANG"
CFLAGSEXCEPTIONS=-fexceptions
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