When the preprocessor encounters an #include statement it now adds
the preprocessor definitions that exist in the included header to its
own set of definitions.
We previously only aggregated the definitions from headers after
processing the source, which was less correct. (For example, there
could be an #ifdef that depends on a definition from another header).
We now call Preprocessor::process_and_lex() and pass the result to the
parser.
Doing the lexing in the preprocessor will allow us to maintain the
original position information of tokens after substituting definitions.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
Under some circumstances we need to ignore unsupported preprocessor
keywords instead of crashing the processing, for example during live
parsing in HackStudio.
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
