* Add kokoro build for python source package

* Use libc++ for xcode 10 (#5303)

The xcode 10 removes the deprecated libstdc++ library. We could set
"MACOSX_DEPLOYMENT_TARGET" to "10.9" to use libc++ instead.

* Add python 3.7 build

* Add build for python 3.7 on linux and windows

* Remove unused source build

* Add comment

* Fix $MACOSX_DEPLOYMENT_TARGET mismatch

* Fix MACOSX_DEPLOYMENT_TARGET mismatch

* Add missing import for sysconfig

* Add missing imports

* adds string-to-int and int-to-string methods to enums

* remove check for valueToName property in EnumTrait

* Remove unused imports

* Update to avoid using EnumTrait

* Remove EnumTrait

* Update enum types

* Move name and value methods into generated classes

* Remove functions from GPBUtil

* Test well known enums

* Implement enum value to/from name in c extension

* Only generate use statement when namespace is present

Avoid octal constants in strutil.cc

In some cases proto files that want/need to use the objc_class_prefix option have
types that already have the prefix on a subset of their names. In this case we don't
want to duplicate the prefix.

Added tests for this (and prefixes in general).

The code now matches what the comment above it actually generates.

Also tweak that code so it actually compiles for me, and to avoid
embedding /* and */ in comments because that's generally a reasonable
thing to trigger warnings.

Add overrides in C++ code.

* fix json_format.ParseDict modifies input

* added unit test

* fix naming

Update add_person.dart

Fixed typo in a function name.

Mostly fix Sun Studio configuration using SunCC compiler (GH #5141)

Instead of using DEPRECATED_ATTRIBUTE from AvailabilityMacros.h, we should introduce a Google-specific Objective-C protobuf deprecation annotation. This helps address IWYU issues with using DEPRECATED_ATTRIBUTE and also enables allows clients to redefine the macro to treat protobuf warnings differently than other types of warnings (e.g., treating protobuf deprecation warnings as errors or ignoring them).

Some changes to the ObjC code generator to support importing into Google.

For messages that have multiple extension ranges, this will improve things
by avoiding repeated work.  For messages with a single range, it should
be a wash.

- Sort the list of set extensions once during serialization and reuse the list.
- Break out of the serialization loop as soon as the loop has moved pasted at
  accepted range for field ids.

* Fix most of the unused variable warnings in Ruby tests

* Add encoded_field_b back in tests/common_tests.rb

* Update README.md

* Migrate to new `ctx.actions` API

This allows building with --incompatible_new_actions_api.

* Fix typo

- removed use of GOOGLE_DISALLOW_EVIL_CONSTRUCTORS
  in favor of deleting them C++11 style.
- removed forward declarations of protobuf core types.
- ensured that namespaces "google" and "protobuf" are
  always opened/closed together.

Make sure to install stubs/strutil.h

Generated code now pulls in this header transitively, so it needs to be
installed.

If a proto has multiple extension ranges back to back, don't double
print the first items as they also are the ending range of the
previous.

Using NSCoding with a Message that has extensions is risky because
when reloaded, there is no way to provide a registry through the
NSCoding plumbing, so output a warnings to atleast give developers
a hint about the potential issues.

Removed stubs/singleton.h

cpp_generator: Add generator options for --cpp_out.

The builds were failing under Xcode 10 because of the new build system.
Even when reverted to the old build system, the build was failing
on the analyzer and swift bridging header, so it seems the general
logic for searching for things was changed in a way the setting does
not always cover.

- Disable HeaderMaps.
- Set user header search paths instead of system search paths.
- Turn off always search user paths (now recommended).

Tested in Xcode 10.1 and 9.4.1; both are able to build/pass with this.

Previously --cpp_out:lite was available to force the optimization mode
to the lite runtime. This adds --cpp_out=speed:...
which is needed to override the file specific options in cases where
libprotobuf-mutator is used for fuzzing since it depends on reflection.
Signed-off-by: Allen Webb <allenwebb@google.com>

compiler/cpp: replace NULL with nullptr

This avoids compiler errors/warnings if zero-as-null-pointer-constant is
considered an error or warning.

This header is no longer used, so we can delete it. I also tweaked
Makefile.am to fix the distcheck test.

* Increase C# default recursion limit to 100

This matches the Java and C++ defaults.

* Change compatibility tests to use execution-time default recursion limit

This way the same tests should pass against all versions, even
if the recursion limit changes. (The tests will be testing whether
different messages work, admittedly - but that's probably fine.)

Add missing include guard to zip_writer.h

Integrated internal changes from Google

Import versions from @bazel_skylib//lib:versions.bzl

options: reserved extension range for CSI