bjoernager/rust
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Auto merge of #96800 - nbdd0121:const, r=nagisa

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Permit `asm_const` and `asm_sym` to reference generic params

Related #96557

These constructs will be allowed:
```rust
fn foofoo<const N: usize>() {}

unsafe fn foo<const N: usize>() {
    asm!("/* {0} */", const N);
    asm!("/* {0} */", const N + 1);
    asm!("/* {0} */", sym foofoo::<N>);
}

fn barbar<T>() {}

unsafe fn bar<T>() {
    asm!("/* {0} */", const std::mem::size_of::<T>());
    asm!("/* {0} */", const std::mem::size_of::<(T, T)>());
    asm!("/* {0} */", sym barbar::<T>);
    asm!("/* {0} */", sym barbar::<(T, T)>);
}
```

`@Amanieu,` I didn't switch inline asms to use `DefKind::InlineAsm`, as I see little value doing that; given that no type inference is needed, it will only make typecking slower and more complex but will have no real gains. I did switch them to follow the same code path as inline asm during symbol resolution, though.
The `error: unconstrained generic constant` you mentioned in #76001 is due to the fact that `to_const` will actually add a wfness obligation to the constant, which we don't need for `asm_const`, so I have that removed.

`@rustbot` label: +A-inline-assembly +F-asm
This commit is contained in:
bors 2022-05-18 15:07:47 +00:00
commit 10d9ecda48
12 changed files with 117 additions and 59 deletions
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8
compiler/rustc_typeck/src/check/expr.rs
View file

@ -2641,10 +2641,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
self.check_expr_asm_operand(out_expr, false);
}
}
hir::InlineAsmOperand::Const { anon_const }
| hir::InlineAsmOperand::SymFn { anon_const } => {
self.to_const(anon_const);
}
// `AnonConst`s have their own body and is type-checked separately.
// As they don't flow into the type system we don't need them to
// be well-formed.
hir::InlineAsmOperand::Const { .. } | hir::InlineAsmOperand::SymFn { .. } => {}
hir::InlineAsmOperand::SymStatic { .. } => {}
}
}

12
compiler/rustc_typeck/src/collect.rs
View file

@ -1556,6 +1556,18 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
Some(tcx.typeck_root_def_id(def_id))
}
// Exclude `GlobalAsm` here which cannot have generics.
Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
if asm.operands.iter().any(|(op, _op_sp)| match op {
hir::InlineAsmOperand::Const { anon_const }
| hir::InlineAsmOperand::SymFn { anon_const } => {
anon_const.hir_id == hir_id
}
_ => false,
}) =>
{
Some(parent_def_id.to_def_id())
}
_ => None,
}
}