port.h #includes various headers in order to define byteswap functions, but it
currently does so from inside the google::protobuf namespace. This can cause
bizarre symbol conflicts and other build errors as these headers' contents are
then included inside this namespace.
Instead, #include the relevant headers above the namespace declarations.
Updating to the current protobuf version caused the following build errors in
Chromium when using Clang on Windows:
..\..\third_party\protobuf\src\google/protobuf/stubs/fastmem.h(67,43) : error: equality comparison with extraneous parentheses [-Werror,-Wparentheses-equality]
if (GOOGLE_PREDICT_FALSE(n_rounded_down == 0)) { // n <= 7
~~~~~~~~~~~~~~~^~~~
The problem is that on Windows, GOOGLE_PREDICT_FALSE is #defined to nothing, so
the code expands to 'if ((n_rounded_down == 0))', which Clang warns about.
Clang would not have warned if the extra parentheses came from the macro,
but in this case they don't because the macro is just dropped.
Fix this by making the macros behave as an identity function instead of just
getting dropped.
This is closer to what these macros look like in stubs/port.h internally.
We now do this in protoc instead of the generation simpler.
Benefits:
- Generation script is simpler
- Detection is simpler as we now only need to care about one filename
- The embedded descriptor knows itself as "google/protobuf/descriptor.proto" avoiding dependency issues
This PR also makes the "invalid dependency" exception clearer in terms of expected and actual dependencies.
See issue #240 - MSVC in VS2015 seems to inline a function it shouldn't. My original workaround was to disable inlining for the whole file, but I found a way to do it on just this specific function using __declspec(noinline).
Unfortunately __declspec has to go at the start of the function declaration, while __attribute in GCC can go either before or after. I had to move lots of GOOGLE_ATTRIBUTE_NOLINE to make it compile. I have not yet tested this change with GCC.
Will there be other side effects of defining this, given it wasn't previously?
I also noticed a few functions marked with both the 'inline' keyword, and GOOGLE_ATTRIBUTE_NOINLINE - huh? Is there an explanation for this, or is it an oversight?
