Rollup merge of #152173 - 9SonSteroids:fn_ptr_type_info, r=oli-obk
Reflection TypeKind::FnPtr This is for https://github.com/rust-lang/rust/issues/146922. Const-eval currently lacks full support for function pointer (fn) types. We should implement handling of FnPtr TypeKind, covering safe and unsafe functions, Rust and custom ABIs, input and output types, higher-ranked lifetimes, and variadic functions.
This commit is contained in:
Jonathan Brouwer
GitHub
commit
b1880bfbfb
5 changed files with 289 additions and 3 deletions
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@ -2,12 +2,12 @@ mod adt;
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use std::borrow::Cow;
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use rustc_abi::{FieldIdx, VariantIdx};
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use rustc_abi::{ExternAbi, FieldIdx, VariantIdx};
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use rustc_ast::Mutability;
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use rustc_hir::LangItem;
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use rustc_middle::span_bug;
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use rustc_middle::ty::layout::TyAndLayout;
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use rustc_middle::ty::{self, Const, ScalarInt, Ty};
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use rustc_middle::ty::{self, Const, FnHeader, FnSigTys, ScalarInt, Ty, TyCtxt};
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use rustc_span::{Symbol, sym};
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use crate::const_eval::CompileTimeMachine;
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@ -188,10 +188,21 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
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self.write_dyn_trait_type_info(dyn_place, *predicates, *region)?;
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variant
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}
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ty::FnPtr(sig, fn_header) => {
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let (variant, variant_place) =
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self.downcast(&field_dest, sym::FnPtr)?;
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let fn_ptr_place =
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self.project_field(&variant_place, FieldIdx::ZERO)?;
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// FIXME: handle lifetime bounds
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let sig = sig.skip_binder();
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self.write_fn_ptr_type_info(fn_ptr_place, &sig, fn_header)?;
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variant
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}
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ty::Foreign(_)
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| ty::Pat(_, _)
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| ty::FnDef(..)
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| ty::FnPtr(..)
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| ty::UnsafeBinder(..)
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| ty::Closure(..)
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| ty::CoroutineClosure(..)
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@ -402,6 +413,65 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
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interp_ok(())
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}
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pub(crate) fn write_fn_ptr_type_info(
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&mut self,
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place: impl Writeable<'tcx, CtfeProvenance>,
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sig: &FnSigTys<TyCtxt<'tcx>>,
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fn_header: &FnHeader<TyCtxt<'tcx>>,
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) -> InterpResult<'tcx> {
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let FnHeader { safety, c_variadic, abi } = fn_header;
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for (field_idx, field) in
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place.layout().ty.ty_adt_def().unwrap().non_enum_variant().fields.iter_enumerated()
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{
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let field_place = self.project_field(&place, field_idx)?;
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match field.name {
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sym::unsafety => {
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self.write_scalar(Scalar::from_bool(safety.is_unsafe()), &field_place)?;
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}
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sym::abi => match abi {
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ExternAbi::C { .. } => {
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let (rust_variant, _rust_place) =
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self.downcast(&field_place, sym::ExternC)?;
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self.write_discriminant(rust_variant, &field_place)?;
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}
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ExternAbi::Rust => {
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let (rust_variant, _rust_place) =
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self.downcast(&field_place, sym::ExternRust)?;
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self.write_discriminant(rust_variant, &field_place)?;
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}
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other_abi => {
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let (variant, variant_place) = self.downcast(&field_place, sym::Named)?;
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let str_place = self.allocate_str_dedup(other_abi.as_str())?;
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let str_ref = self.mplace_to_ref(&str_place)?;
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let payload = self.project_field(&variant_place, FieldIdx::ZERO)?;
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self.write_immediate(*str_ref, &payload)?;
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self.write_discriminant(variant, &field_place)?;
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}
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},
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sym::inputs => {
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let inputs = sig.inputs();
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self.allocate_fill_and_write_slice_ptr(
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field_place,
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inputs.len() as _,
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|this, i, place| this.write_type_id(inputs[i as usize], &place),
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)?;
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}
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sym::output => {
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let output = sig.output();
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self.write_type_id(output, &field_place)?;
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}
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sym::variadic => {
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self.write_scalar(Scalar::from_bool(*c_variadic), &field_place)?;
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}
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other => span_bug!(self.tcx.def_span(field.did), "unimplemented field {other}"),
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}
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}
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interp_ok(())
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}
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pub(crate) fn write_pointer_type_info(
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&mut self,
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place: impl Writeable<'tcx, CtfeProvenance>,
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@ -242,6 +242,8 @@ symbols! {
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Equal,
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Err,
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Error,
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ExternC,
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ExternRust,
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File,
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FileType,
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Float,
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@ -250,6 +252,7 @@ symbols! {
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Fn,
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FnMut,
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FnOnce,
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FnPtr,
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Formatter,
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Forward,
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From,
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@ -303,6 +306,7 @@ symbols! {
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Mutex,
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MutexGuard,
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N,
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Named,
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NonNull,
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NonZero,
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None,
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@ -1290,6 +1294,7 @@ symbols! {
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inline_const,
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inline_const_pat,
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inout,
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inputs,
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instant_now,
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instruction_set,
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integer_: "integer", // underscore to avoid clashing with the function `sym::integer` below
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@ -1660,6 +1665,7 @@ symbols! {
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os_string_as_os_str,
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other,
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out,
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output,
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overflow_checks,
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overlapping_marker_traits,
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owned_box,
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@ -2439,6 +2445,7 @@ symbols! {
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unsafe_no_drop_flag,
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unsafe_pinned,
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unsafe_unpin,
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unsafety,
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unsize,
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unsized_const_param_ty,
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unsized_const_params,
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@ -2483,6 +2490,7 @@ symbols! {
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value,
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values,
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var,
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variadic,
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variant_count,
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variants,
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vec,
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@ -75,6 +75,8 @@ pub enum TypeKind {
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Reference(Reference),
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/// Pointers.
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Pointer(Pointer),
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/// Function pointers.
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FnPtr(FnPtr),
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/// FIXME(#146922): add all the common types
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Other,
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}
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@ -305,3 +307,39 @@ pub struct Pointer {
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/// Whether this pointer is mutable or not.
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pub mutable: bool,
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}
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#[derive(Debug)]
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#[unstable(feature = "type_info", issue = "146922")]
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/// Function pointer, e.g. fn(u8),
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pub struct FnPtr {
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/// Unsafety, true is unsafe
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pub unsafety: bool,
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/// Abi, e.g. extern "C"
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pub abi: Abi,
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/// Function inputs
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pub inputs: &'static [TypeId],
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/// Function return type, default is TypeId::of::<()>
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pub output: TypeId,
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/// Vardiadic function, e.g. extern "C" fn add(n: usize, mut args: ...);
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pub variadic: bool,
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}
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#[derive(Debug, Default)]
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#[non_exhaustive]
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#[unstable(feature = "type_info", issue = "146922")]
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/// Abi of [FnPtr]
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pub enum Abi {
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/// Named abi, e.g. extern "custom", "stdcall" etc.
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Named(&'static str),
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/// Default
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#[default]
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ExternRust,
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/// C-calling convention
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ExternC,
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}
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@ -1,3 +1,4 @@
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mod fn_ptr;
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mod type_info;
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use core::mem::*;
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169
library/coretests/tests/mem/fn_ptr.rs
Normal file
169
library/coretests/tests/mem/fn_ptr.rs
Normal file
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@ -0,0 +1,169 @@
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use std::any::TypeId;
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use std::mem::type_info::{Abi, FnPtr, Type, TypeKind};
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const STRING_TY: TypeId = const { TypeId::of::<String>() };
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const U8_TY: TypeId = const { TypeId::of::<u8>() };
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const _U8_REF_TY: TypeId = const { TypeId::of::<&u8>() };
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const UNIT_TY: TypeId = const { TypeId::of::<()>() };
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#[test]
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fn test_fn_ptrs() {
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let TypeKind::FnPtr(FnPtr {
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unsafety: false,
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abi: Abi::ExternRust,
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inputs: &[],
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output,
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variadic: false,
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}) = (const { Type::of::<fn()>().kind })
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else {
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panic!();
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};
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assert_eq!(output, UNIT_TY);
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}
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#[test]
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fn test_ref() {
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const {
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// references are tricky because the lifetimes give the references different type ids
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// so we check the pointees instead
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let TypeKind::FnPtr(FnPtr {
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unsafety: false,
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abi: Abi::ExternRust,
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inputs: &[ty1, ty2],
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output,
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variadic: false,
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}) = (const { Type::of::<fn(&u8, &u8)>().kind })
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else {
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panic!();
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};
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if output != UNIT_TY {
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panic!();
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}
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let TypeKind::Reference(reference) = ty1.info().kind else {
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panic!();
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};
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if reference.pointee != U8_TY {
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panic!();
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}
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let TypeKind::Reference(reference) = ty2.info().kind else {
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panic!();
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};
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if reference.pointee != U8_TY {
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panic!();
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}
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}
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}
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#[test]
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fn test_unsafe() {
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let TypeKind::FnPtr(FnPtr {
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unsafety: true,
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abi: Abi::ExternRust,
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inputs: &[],
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output,
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variadic: false,
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}) = (const { Type::of::<unsafe fn()>().kind })
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else {
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panic!();
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};
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assert_eq!(output, UNIT_TY);
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}
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#[test]
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fn test_abi() {
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let TypeKind::FnPtr(FnPtr {
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unsafety: false,
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abi: Abi::ExternRust,
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inputs: &[],
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output,
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variadic: false,
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}) = (const { Type::of::<extern "Rust" fn()>().kind })
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else {
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panic!();
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};
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assert_eq!(output, UNIT_TY);
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let TypeKind::FnPtr(FnPtr {
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unsafety: false,
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abi: Abi::ExternC,
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inputs: &[],
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output,
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variadic: false,
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}) = (const { Type::of::<extern "C" fn()>().kind })
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else {
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panic!();
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};
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assert_eq!(output, UNIT_TY);
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let TypeKind::FnPtr(FnPtr {
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unsafety: true,
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abi: Abi::Named("system"),
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inputs: &[],
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output,
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variadic: false,
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}) = (const { Type::of::<unsafe extern "system" fn()>().kind })
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else {
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panic!();
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};
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assert_eq!(output, UNIT_TY);
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}
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#[test]
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fn test_inputs() {
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let TypeKind::FnPtr(FnPtr {
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unsafety: false,
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abi: Abi::ExternRust,
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inputs: &[ty1, ty2],
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output,
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variadic: false,
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}) = (const { Type::of::<fn(String, u8)>().kind })
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else {
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panic!();
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};
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assert_eq!(output, UNIT_TY);
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assert_eq!(ty1, STRING_TY);
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assert_eq!(ty2, U8_TY);
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let TypeKind::FnPtr(FnPtr {
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unsafety: false,
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abi: Abi::ExternRust,
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inputs: &[ty1, ty2],
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output,
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variadic: false,
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}) = (const { Type::of::<fn(val: String, p2: u8)>().kind })
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else {
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panic!();
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};
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assert_eq!(output, UNIT_TY);
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assert_eq!(ty1, STRING_TY);
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assert_eq!(ty2, U8_TY);
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}
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#[test]
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fn test_output() {
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let TypeKind::FnPtr(FnPtr {
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unsafety: false,
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abi: Abi::ExternRust,
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inputs: &[],
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output,
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variadic: false,
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}) = (const { Type::of::<fn() -> u8>().kind })
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else {
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panic!();
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};
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assert_eq!(output, U8_TY);
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}
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#[test]
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fn test_variadic() {
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let TypeKind::FnPtr(FnPtr {
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unsafety: false,
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abi: Abi::ExternC,
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inputs: [ty1],
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output,
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variadic: true,
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}) = &(const { Type::of::<extern "C" fn(u8, ...)>().kind })
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else {
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panic!();
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};
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assert_eq!(output, &UNIT_TY);
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assert_eq!(*ty1, U8_TY);
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}
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