[clang] Fix crashes when passing VLA to va_arg (#119563)

Closes #119360.

This bug occurs when passing a VLA to `va_arg`. Since the return value
is inferred to be an array, it triggers
`ScalarExprEmitter::VisitCastExpr`, which converts it to a pointer and
subsequently calls `CodeGenFunction::EmitAggExpr`. At this point,
because the inferred type is an `AggExpr` instead of a `ScalarExpr`,
`ScalarExprEmitter::VisitVAArgExpr` is not invoked, and as a result,
`CodeGenFunction::EmitVariablyModifiedType` is also not called, leading
to the size of the VLA not being retrieved.
The solution is to move the call to
`CodeGenFunction::EmitVariablyModifiedType` into
`CodeGenFunction::EmitVAArg`, ensuring that the size of the VLA is
correctly obtained regardless of whether the expression is an `AggExpr`
or a `ScalarExpr`.

0 files changed, 0 insertions, 0 deletions