src/librustc/ty/diagnostics.rs

//! Diagnostics related methods for `TyS`.

use crate::ty::sty::InferTy;
use crate::ty::TyKind::*;
use crate::ty::TyS;

impl<'tcx> TyS<'tcx> {
    /// Similar to `TyS::is_primitive`, but also considers inferred numeric values to be primitive.
    pub fn is_primitive_ty(&self) -> bool {
        match self.kind {
            Bool
            | Char
            | Str
            | Int(_)
            | Uint(_)
            | Float(_)
            | Infer(InferTy::IntVar(_))
            | Infer(InferTy::FloatVar(_))
            | Infer(InferTy::FreshIntTy(_))
            | Infer(InferTy::FreshFloatTy(_)) => true,
            _ => false,
        }
    }

    /// Whether the type is succinctly representable as a type instead of just referred to with a
    /// description in error messages. This is used in the main error message.
    pub fn is_simple_ty(&self) -> bool {
        match self.kind {
            Bool
            | Char
            | Str
            | Int(_)
            | Uint(_)
            | Float(_)
            | Infer(InferTy::IntVar(_))
            | Infer(InferTy::FloatVar(_))
            | Infer(InferTy::FreshIntTy(_))
            | Infer(InferTy::FreshFloatTy(_)) => true,
            Ref(_, x, _) | Array(x, _) | Slice(x) => x.peel_refs().is_simple_ty(),
            Tuple(tys) if tys.is_empty() => true,
            _ => false,
        }
    }

    /// Whether the type is succinctly representable as a type instead of just referred to with a
    /// description in error messages. This is used in the primary span label. Beyond what
    /// `is_simple_ty` includes, it also accepts ADTs with no type arguments and references to
    /// ADTs with no type arguments.
    pub fn is_simple_text(&self) -> bool {
        match self.kind {
            Adt(_, substs) => substs.types().next().is_none(),
            Ref(_, ty, _) => ty.is_simple_text(),
            _ => self.is_simple_ty(),
        }
    }

    /// Whether the type can be safely suggested during error recovery.
    pub fn is_suggestable(&self) -> bool {
        match self.kind {
            Opaque(..) | FnDef(..) | FnPtr(..) | Dynamic(..) | Closure(..) | Infer(..)
            | Projection(..) => false,
            _ => true,
        }
    }
}