Xcode 10+ is needed for exhaustive C++17 support (gnu++17).
11.3 is the latest available version on Travis, and we don't have a
specific reason not to use it.
Follow-up to #36457.
It's now available and allows us to have a better default environment,
with GCC 7.4.0 and Clang 7.
We now need GCC 7+ for C++17 support so it's more efficient to upgrade
the image than to install it on Ubuntu 16.04 (xenial).
Also fixes a couple -Wdeprecated-declarations warnings on macOS now
that we build against macOS 10.12.
Fix -Wunused-variable, -Wunused-but-set-variable and -Wswitch warnings
raised by GCC 8 and 9.
Fix -Wunused-function, -Wunused-private-field and
-Wtautological-constant-out-of-range-compare raised by Clang.
Fix MSVC 2019 warning C4804 (unsafe use of type 'bool' in comparison
operation).
GCC -Wcpp warnings/Clang -W#warnings (`#warning`) are no longer raising
errors and will thus not abort compilation with `werror=yes`.
Treat glslang headers are system headers to avoid raising warnings.
Re-enables us to build with `werror=yes` on Linux and macOS, thus
catching warnings that would be introduced by new code.
Fixes#36132.
The UX is pretty bad, and the fact that all reports are private by
default with no option to make them public makes Coverity Scan hardly
usable in a community-driven project.
Travis CI upgraded their Xenial VMs to default to openjdk11, which
is not working properly for sdkmanager, so we can no longer accept
licenses for the SDK.
They don't really seem to care about providing a good alternative
for us from the few threads I read, so let's just force openjdk8
back.
Wrapped libpng usage in a pair of functions under PNGDriverCommon,
which convert between Godot Image and png data.
Switched to libpng 1.6 simplified API for ease of maintenance.
Implemented ImageLoaderPNG and ResourceSaverPNG in terms of
PNGDriverCommon functions.
Travis, switched to builtin libpng (thus builtin freetype and zlib also)
so we can build on Xenial.
This increases the build coverage by making sure the Linux
export template still compiles when 3D support is disabled.
This also adds human-readable names to each job, which are displayed
on the Travis CI interface.
Not sure why we switched from homebrew to scons-local anymore,
but pip should work just fine and is recommended by upstream.
Downloads of scons-local from SourceForge were quite iffy, so
this should help avoid CI errors due to not having downloaded
SCons successfully.
Setting Python's user binary PATH seems necessary on Travis/OSX
as per travis-ci/travis-ci#5030 (confirmed that 'scons' is not
in PATH without it).
Also increase AppVeyor cache size to 1024,
should match what is available for us in the free plan:
https://www.appveyor.com/docs/build-cache/#cache-size-beta
And drop obsolete debug_release option for Windows, superseded
by target=release and debug_symbols=yes.
