Context:
- https://blog.rust-lang.org/2024/09/04/cve-2024-43402.html
- https://github.com/rust-lang/rust/pull/129962
Note that the Rust test case for this checks that it executes the batch file successfully with the proper mitigation in place, while the Zig test case expects a FileNotFound error. This is because of a PATHEXT optimization that Zig does, and that Rust doesn't do because Rust doesn't do PATHEXT appending (it only appends .exe specifically). See the added comment for more details.
Adds a CreateProcessFlags packed struct for all the possible flags to
CreateProcessW on windows. In addition, propagates the existing
`start_suspended` option in std.process.Child which was previously only
used on Darwin. Also adds a `create_no_window` option to std.process.Child
which is a commonly used flag for launching console executables on
windows without causing a new console window to "pop up".
While it is not allowed for a function coercion to change whether a
function is generic, it *is* okay to make existing concrete parameters
of a generic function also generic, or vice versa. Either of these cases
implies that the result is a generic function, so comptime type checks
will happen when the function is ultimately called.
Resolves: #21099
This commit reworks how Sema handles arithmetic on comptime-known
values, fixing many bugs in the process.
The general pattern is that arithmetic on comptime-known values is now
handled by the new namespace `Sema.arith`. Functions handling comptime
arithmetic no longer live on `Value`; this is because some of them can
emit compile errors, so some *can't* go on `Value`. Only semantic
analysis should really be doing arithmetic on `Value`s anyway, so it
makes sense for it to integrate more tightly with `Sema`.
This commit also implements more coherent rules surrounding how
`undefined` interacts with comptime and mixed-comptime-runtime
arithmetic. The rules are as follows.
* If an operation cannot trigger Illegal Behavior, and any operand is
`undefined`, the result is `undefined`. This includes operations like
`0 *| undef`, where the LHS logically *could* be used to determine a
defined result. This is partly to simplify the language, but mostly to
permit codegen backends to represent `undefined` values as completely
invalid states.
* If an operation *can* trigger Illegal Behvaior, and any operand is
`undefined`, then Illegal Behavior results. This occurs even if the
operand in question isn't the one that "decides" illegal behavior; for
instance, `undef / 1` is undefined. This is for the same reasons as
described above.
* An operation which would trigger Illegal Behavior, when evaluated at
comptime, instead triggers a compile error. Additionally, if one
operand is comptime-known undef, such that the other (runtime-known)
operand isn't needed to determine that Illegal Behavior would occur,
the compile error is triggered.
* The only situation in which an operation with one comptime-known
operand has a comptime-known result is if that operand is undefined,
in which case the result is either undefined or a compile error per
the above rules. This could potentially be loosened in future (for
instance, `0 * rt` could be comptime-known 0 with a runtime assertion
that `rt` is not undefined), but at least for now, defining it more
conservatively simplifies the language and allows us to easily change
this in future if desired.
This commit fixes many bugs regarding the handling of `undefined`,
particularly in vectors. Along with a collection of smaller tests, two
very large test cases are added to check arithmetic on `undefined`.
The operations which have been rewritten in this PR are:
* `+`, `+%`, `+|`, `@addWithOverflow`
* `-`, `-%`, `-|`, `@subWithOverflow`
* `*`, `*%`, `*|`, `@mulWithOverflow`
* `/`, `@divFloor`, `@divTrunc`, `@divExact`
* `%`, `@rem`, `@mod`
Other arithmetic operations are currently unchanged.
Resolves: #22743Resolves: #22745Resolves: #22748Resolves: #22749Resolves: #22914
