RFC: Avoid warnings in MSVC builds, add flag for similar warnings for GCC/Clang

I'm sure that some of these changes are more acceptable than others; I can split them up in separate merge requests if there are things that are OK to be merged soon while others require more discussion.

This is an alternative to !563 (closed).

I kind of like it, of course, but I fear other people will object.

added buildsystem label

1-7 and 10-11 should not be debatable. 8-9 maybe.

Are all changes in 8 required to avoid warnings?

Are all changes in 8 required to avoid warnings?

Yes. Most of them are necessary for a warning free build with MSVC. A couple of them (all changes to lf_mask.c and one of the changes to checkasm.c) are needed for building warning free with -Wshorten-64-to-32 with clang.

I can do a separate MR with the non-debatable parts, to reduce the amount of things under discussion.

mentioned in merge request !570 (merged)

I'll rebase this on latest master once !570 (merged) is done.

Some small nits. I think overall I understand the logic behind the changes and although I think it's ugly as sin, I also understand if some people prefer to merge it anyway. Warning-free compiles are important and useful in and by themselves.

added 12 commits

• 4a4eeb39...b1d571f1 - 8 commits from branch videolan:master
• 0301eb16 - Add casts to silence warnings about intended type conversions/shortenings
• b2dd218b - obu: Initialize off_before_idx[0], fix MSVC warning about uninitialized use
• 1679fe5f - meson: Try building with -Wshorten-64-to-32
• 3bb47def - cdef_apply_tmpl: Restore the y variables to int

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resolved all discussions

This was maybe the biggest surprise in the patchset. masks[0] is uint64_t and has got values set outside of the uint32_t range, but we intentionally need to only use the lowest half, otherwise this really doesn't work any longer.

Therefore I used an (uint32_t) cast here, to indicate that we really explicitly want to truncate it to 32 bits (e.g. for completely hypothetical ABIs with a 64 bit int type).

I believe the second uint64_t has just one used bit, which for the first one is top/right and for the second one is top/left (or something like that). The first 32 bit are the regular top/left edges.

mentioned in issue #242 (closed)

added 15 commits

• 3bb47def...0d18b15a - 11 commits from branch videolan:master
• 390489c7 - Add casts to silence warnings about intended type conversions/shortenings
• ddb653e2 - obu: Initialize off_before_idx[0], fix MSVC warning about uninitialized use
• 05a1267a - meson: Try building with -Wshorten-64-to-32
• 5d3efc49 - cdef_apply_tmpl: Restore the y variables to int

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added 1 commit

• 8872811e - cdef_apply_tmpl: Restore the y variables to int

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added 5 commits

• 3cf4d32e - 1 commit from branch videolan:master
• 13b7df8d - Add casts to silence warnings about intended type conversions/shortenings
• baba5fc3 - obu: Initialize off_before_idx[0], fix MSVC warning about uninitialized use
• fe17bd16 - cdef_apply_tmpl: Restore the y variables to int
• ced01fec - meson: Try building with -Wshorten-64-to-32

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So, based on the discussion on irc, this should be acceptable. Who wants to merge it?

added 8 commits

• ced01fec...4c21c931 - 4 commits from branch videolan:master
• 35b1cde2 - Add casts to silence warnings about intended type conversions/shortenings
• 65d963d4 - obu: Initialize off_before_idx[0], fix MSVC warning about uninitialized use
• 703c72fd - cdef_apply_tmpl: Restore the y variables to int
• 93ab93de - meson: Try building with -Wshorten-64-to-32

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