Quiet down a warning from MSVC about how we're potentially losing data. This is safe since we've explicitly tested that it's within the range of 0-100.
Move to the `git_error` name in the internal API for error-related functions.
The function `parse_number` was replaced by `git_parse_advance_digit` which is provided by the parser interface in commit 252f2eeee (parse: implement and use `git_parse_advance_digit`, 2017-07-14). As there are no remaining callers, remove it.
A lot of compilers nowadays generate warnings when there are cases in a switch statement which implicitly fall through to the next case. To avoid this warning, the last line in the case that is falling through can have a comment matching a regular expression, where one possible comment body would be `/* fall through */`. An alternative to the comment would be an explicit attribute like e.g. `[[clang::fallthrough]` or `__attribute__ ((fallthrough))`. But GCC only introduced support for such an attribute recently with GCC 7. Thus, and also because the fallthrough comment is supported by most compilers, we settle for using comments instead. One shortcoming of that method is that compilers are very strict about that. Most interestingly, that comment _really_ has to be the last line. In case a closing brace follows the comment, the heuristic will fail.
patch_parse: fix parsing unquoted filenames with spaces
Strict aliasing rules dictate that for most data types, you are not allowed to cast them to another data type and then access the casted pointers. While this works just fine for most compilers, technically we end up in undefined behaviour when we hurt that rule. Our current refcounting code makes heavy use of casting and thus violates that rule. While we didn't have any problems with that code, Travis started spitting out a lot of warnings due to a change in their toolchain. In the refcounting case, the code is also easy to fix: as all refcounting-statements are actually macros, we can just access the `rc` field directly instead of casting. There are two outliers in our code where that doesn't work. Both the `git_diff` and `git_patch` structures have specializations for generated and parsed diffs/patches, which directly inherit from them. Because of that, the refcounting code is only part of the base structure and not of the children themselves. We can help that by instead passing their base into `GIT_REFCOUNT_INC`, though.
The git patch format allows for having unquoted paths with whitespaces
inside. This format becomes ambiguous to parse, e.g. in the following
example:
diff --git a/file b/with spaces.txt b/file b/with spaces.txt
While we cannot parse this in a correct way, we can instead use the
"---" and "+++" lines to retrieve the file names, as the path is not
followed by anything here but spans the complete remaining line. Because
of this, we can simply bail outwhen parsing the "diff --git" header here
without an actual error and then proceed to just take the paths from the
other headers.
When parsing the "---" and "+++" line, we stop after the first whitespace inside of the filename. But as files containing whitespaces do not need to be quoted, we should instead use the complete line here. This fixes parsing patches with unquoted paths with whitespaces.