Actually, that last revision can be simpler -- we don't need to parse strings at all, as simply entering 1e1000 as a float literal in Python will be evaluated as infinity.

In Python, avoid relying on float('inf') and float('nan') as these don't work on Windows with Python pre-2.6.

In Java's TextFormat, correcty concatenate adjacent string literals, as C++ does.  Also fix a bug in handling of single-quoted strings.

Make extension identifiers final.  This improves security when untrusted code is present in the same class loader.  In order to get around initialization ordering issues, I simply made the constructor for extension identifiers take no arguments and deferred initialization to an internalInit() method, which generated code will always call during init.

getExtension() on an empty repeated field should return an empty list, not a singular default value.

When serializing to an ostream, verify that there were no stream-level errors before returning success.

Clarify that pushLimit() does not limit the number of bytes CodedInputStream will read from the underlying InputStream.

Ensure that 'once' objects are declared using the macro.  This is either the third or fourth time I've screwed this up when down-integrating, because our internal code does not require the macro (it's not portable) and on Linux a pthread_once_t that is zero-initialized just happens to work.  So, I only discover the problem when I test on Mac, then kick myself for making the same mistake yet again.  No more!  This time, I have renamed GoogleOnceType to ProtobufOnceType, thus making the type name differ from our internal code.  As a result, if you don't update the decls to use the macros, they won't compile.  Hah!  Take that, future self!

be properly set. writeTo() may be invoked without a call to
getSerializedSize(), so the generated serialization methods would
write a length of 0 for non-empty packed fields. Just call
getSerializedSize() at the beginning of writeTo(): although this
means that we may compute the byte size needlessly when there
are no packed fields, in practice, getSerializedSize() will
already have been called - all of the writeTo() wrappers in
AbstractMessageLite invoke it.

Tested: new unittest case in WireFormatTest.java now passes

Explicitly call superclass constructor in generated code to avoid pedantic warning.  Based on patch from Oleg Smolsky.

Fix cross-compiling when building in a dedicated build directory.  Fix pointed out by Pierre Kestener.