* avoid undefined behavior from UNREACHABLE on reachable code paths
UNREACHABLE expands to __assume(false) / __builtin_unreachable() in
release builds, which is undefined behavior if the code is ever actually
reached. Many UNREACHABLE sites only guard against unexpected-but-
possible runtime states (values from tables, mission/save files, network
packets, scripting, or user input), so reaching them should degrade
gracefully rather than invoke UB.
Replace UNREACHABLE with Assertion(false, ...) at all such sites. It
still pops an error in debug builds, but in release it is a harmless
no-op that simply falls through to the following code. Sites that are
genuinely unreachable by local invariants (e.g. a switch over a bounded
random number) are left as UNREACHABLE.
A few converted sites had no safe fall-through -- an uninitialized read,
null dereference, or null call would have followed -- so they also get a
minimal recovery: initialize the value, guard the dereference, return
early, or skip the offending item.
Where the converted site was a simple guard of the form
if (x) { Assertion(false, ...); return; }
hoist the check onto the invariant instead:
Assertion(!x, ...);
if (x) { return; }
This states the expectation directly and shows the offending value in
the debug popup, while keeping the same graceful runtime degradation.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
* addendum
After consultation with Lafiel, use UNREACHABLE in situations that are effectively impossible even if not provably impossible. UNREACHABLE = "this shouldn't ever happen"; Assertion = "if this ever happens, it's a coding error". Also fix a few other sites and change a couple to Warnings.
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Co-authored-by: Claude Opus 4.8 (1M context) <[email protected]>
If invalid UTF-8 is encountered, return the standard Unicode replacement character 0xFFFD. When incrementing or decrementing, make a best effort to follow the code's instructions. It might produce one or more � characters, but that's better than an Error and a hard crash.
Also move character constants to standardized locations.
The code did not account for unicode escape sequences when inserting
scrambling characters which distorted the text and fequently caused
invalid UTF-8 sequences to appear in the text. This fixes that by
using the text iterators already present in the game code. I needed to
rewrite the logic of this block a bit since the previous logic could not
be converted to the way we need to handle unicode sequences at the
moment.
This fixes#1720.
This adds proper Unicode support by allowing the parse system to read
UTF-8 encoded files. The new mode is controlled by a mod option which
allows older mods to continue using the legacy text encoding.
That option changes the behavior of several systems in FSO. It disallows
the usage of Volition fonts since they don't support Unicode encoding
and changes a few usages of special characters to their unicode
counterparts of generic rendering solutions.
This fixes#1415.
