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fix for when C has to return an empty tag union

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Folkert 2023-02-15 15:17:29 +01:00
parent d1a22316fc
commit 178e80fa9a
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2 changed files with 24 additions and 5 deletions
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25
crates/compiler/gen_llvm/src/llvm/build.rs
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@ -3957,20 +3957,35 @@ fn expose_function_to_host_help_c_abi_v2<'a, 'ctx, 'env>(
(RocReturn::ByPointer, CCReturn::Return) => {
// Roc currently puts the return pointer at the end of the argument list.
// As such, we drop the last element here instead of the first.
(&params[..], &param_types[..param_types.len() - 1])
(
&params[..],
&param_types[..param_types.len().saturating_sub(1)],
)
}
// Drop the return pointer the other way, if the C function returns by pointer but Roc
// doesn't
(RocReturn::Return, CCReturn::ByPointer) => (&params[1..], &param_types[..]),
(RocReturn::ByPointer, CCReturn::ByPointer) => {
// Both return by pointer but Roc puts it at the end and C puts it at the beginning
(&params[1..], &param_types[..param_types.len() - 1])
(
&params[1..],
&param_types[..param_types.len().saturating_sub(1)],
)
}
(RocReturn::Return | RocReturn::ByPointer, CCReturn::Void) => {
// the roc function returns a unit value. like `{}` or `{ { {}, {} }, {} }`.
// In C, this is modelled as a function returning void
(
&params[..],
&param_types[..param_types.len().saturating_sub(1)],
)
}
_ => (&params[..], &param_types[..]),
};
debug_assert!(
params.len() == param_types.len(),
debug_assert_eq!(
params.len(),
param_types.len(),
"when exposing a function to the host, params.len() was {}, but param_types.len() was {}",
params.len(),
param_types.len()
@ -5685,6 +5700,8 @@ impl<'ctx> FunctionSpec<'ctx> {
(return_type.unwrap().fn_type(&arguments, false), None)
}
CCReturn::Void => {
// NOTE: there may be a valid return type, but it is zero-sized.
// for instance just `{}` or something more complex like `{ { {}, {} }, {} }`
let arguments = function_arguments(env, argument_types);
(env.context.void_type().fn_type(&arguments, false), None)
}