Re: [meta-browser][PATCH 2/4] chromium: gcc-6 support

[Trevor Woerner <twoerner@gmail.com>]

On Wed 2016-07-20 @ 12:59:21 PM, Khem Raj wrote:
> On Wed, Jul 20, 2016 at 12:51 PM, Trevor Woerner <twoerner@gmail.com> wrote:
> > Allow chromium to build with gcc-6.
> 
> bunch of patches are deleted. Are they upstreamed ? or how do they
> help compiling chromium with gcc6?

At some point in the past (I could figure out who, but I don't want to give
the impression that I'm pointing fingers) someone added the following line to
the recipe:

	-Ddisable_fatal_linker_warnings=1

The *intention* was to keep the build from failing due to compiler -Werror
issues. For whatever reason this line has no effect on the build; the -Werror
is still used, and builds still fail for annoying, non-critical reasons.
Therefore we've amassed a large set of patches that try to fix these
warnings by either fixing the code itself:


	> > ---- a/third_party/ots/src/name.cc
	> > -+++ b/third_party/ots/src/name.cc
	> > -@@ -79,7 +79,7 @@ bool ots_name_parse(Font *font, const uint8_t* data, size_t length) {
	> > -   const char* string_base = reinterpret_cast<const char*>(data) +
	> > -       string_offset;
	> > -
	> > --  NameRecord prev_record;
	> > -+  NameRecord prev_record(0, 0, 0, 0);
	> > -   bool sort_required = false;
	> > -

or by (more likely) some l337 #pragma tricks:


	> > ---- a/third_party/WebKit/Source/wtf/dtoa/bignum.cc
	> > -+++ b/third_party/WebKit/Source/wtf/dtoa/bignum.cc
	> > -@@ -102,7 +102,10 @@
	> > -     }
	> > -
	> > -
	> > -+#pragma GCC diagnostic push
	> > -+#pragma GCC diagnostic warning "-Wstrict-overflow"
	> > -     void Bignum::AssignDecimalString(Vector<const char> value) {
	> > -+#pragma GCC diagnostic pop
	> > -         // 2^64 = 18446744073709551616 > 10^19
	> > -         const int kMaxUint64DecimalDigits = 19;
	> > -         Zero();
	> > -@@ -696,7 +696,10 @@
	> > -     }

What I've done here is to patch the various BUILD.gn files and *gyp files so
that -Werror is actually removed from our build (which was the original
intent), thereby making a number of subsequent patches superfluous.

Given the chromium developers use a completely different compiler and,
therefore, are unlikely to be tripping over the same warning/error problems we
keep seeing, I believe this is a sensible thing to do. Especially since, going
forward, is reduces the maintanance burden, and (in my opinion) the upstream
developers are probably unlikely to ever accept these sorts of patches anyway.