Auto merge of #13546 - Veykril:unsafe-fn-ptr, r=Veykril

Lower unsafety of fn pointer and fn item types

6 files changed, 47 insertions, 18 deletions

diff --git a/crates/hir-def/src/pretty.rs b/crates/hir-def/src/pretty.rs
index 6636c8a23ca..933970d10e4 100644
--- a/crates/hir-def/src/pretty.rs
+++ b/crates/hir-def/src/pretty.rs
@@ -143,9 +143,12 @@ pub(crate) fn print_type_ref(type_ref: &TypeRef, buf: &mut dyn Write) -> fmt::Re
             print_type_ref(elem, buf)?;
             write!(buf, "]")?;
         }
-        TypeRef::Fn(args_and_ret, varargs) => {
+        TypeRef::Fn(args_and_ret, varargs, is_unsafe) => {
             let ((_, return_type), args) =
                 args_and_ret.split_last().expect("TypeRef::Fn is missing return type");
+            if *is_unsafe {
+                write!(buf, "unsafe ")?;
+            }
             write!(buf, "fn(")?;
             for (i, (_, typeref)) in args.iter().enumerate() {
                 if i != 0 {
diff --git a/crates/hir-def/src/type_ref.rs b/crates/hir-def/src/type_ref.rs
index 5b4c71be7fb..f8bb78ddcfe 100644
--- a/crates/hir-def/src/type_ref.rs
+++ b/crates/hir-def/src/type_ref.rs
@@ -119,7 +119,7 @@ pub enum TypeRef {
     Array(Box<TypeRef>, ConstScalarOrPath),
     Slice(Box<TypeRef>),
     /// A fn pointer. Last element of the vector is the return type.
-    Fn(Vec<(Option<Name>, TypeRef)>, bool /*varargs*/),
+    Fn(Vec<(Option<Name>, TypeRef)>, bool /*varargs*/, bool /*is_unsafe*/),
     ImplTrait(Vec<Interned<TypeBound>>),
     DynTrait(Vec<Interned<TypeBound>>),
     Macro(AstId<ast::MacroCall>),
@@ -229,7 +229,7 @@ impl TypeRef {
                     Vec::new()
                 };
                 params.push((None, ret_ty));
-                TypeRef::Fn(params, is_varargs)
+                TypeRef::Fn(params, is_varargs, inner.unsafe_token().is_some())
             }
             // for types are close enough for our purposes to the inner type for now...
             ast::Type::ForType(inner) => TypeRef::from_ast_opt(ctx, inner.ty()),
@@ -263,7 +263,7 @@ impl TypeRef {
         fn go(type_ref: &TypeRef, f: &mut impl FnMut(&TypeRef)) {
             f(type_ref);
             match type_ref {
-                TypeRef::Fn(params, _) => {
+                TypeRef::Fn(params, _, _) => {
                     params.iter().for_each(|(_, param_type)| go(param_type, f))
                 }
                 TypeRef::Tuple(types) => types.iter().for_each(|t| go(t, f)),
diff --git a/crates/hir-ty/src/display.rs b/crates/hir-ty/src/display.rs
index 5ad66132635..a22a4b170f6 100644
--- a/crates/hir-ty/src/display.rs
+++ b/crates/hir-ty/src/display.rs
@@ -1187,8 +1187,11 @@ impl HirDisplay for TypeRef {
                 inner.hir_fmt(f)?;
                 write!(f, "]")?;
             }
-            TypeRef::Fn(parameters, is_varargs) => {
+            &TypeRef::Fn(ref parameters, is_varargs, is_unsafe) => {
                 // FIXME: Function pointer qualifiers.
+                if is_unsafe {
+                    write!(f, "unsafe ")?;
+                }
                 write!(f, "fn(")?;
                 if let Some(((_, return_type), function_parameters)) = parameters.split_last() {
                     for index in 0..function_parameters.len() {
@@ -1203,7 +1206,7 @@ impl HirDisplay for TypeRef {
                             write!(f, ", ")?;
                         }
                     }
-                    if *is_varargs {
+                    if is_varargs {
                         write!(f, "{}...", if parameters.len() == 1 { "" } else { ", " })?;
                     }
                     write!(f, ")")?;
diff --git a/crates/hir-ty/src/lib.rs b/crates/hir-ty/src/lib.rs
index 2b5989c6c6f..b68c764bdca 100644
--- a/crates/hir-ty/src/lib.rs
+++ b/crates/hir-ty/src/lib.rs
@@ -210,6 +210,7 @@ pub(crate) fn make_binders<T: HasInterner<Interner = Interner>>(
 pub struct CallableSig {
     params_and_return: Arc<[Ty]>,
     is_varargs: bool,
+    safety: Safety,
 }
 
 has_interner!(CallableSig);
@@ -218,9 +219,14 @@ has_interner!(CallableSig);
 pub type PolyFnSig = Binders<CallableSig>;
 
 impl CallableSig {
-    pub fn from_params_and_return(mut params: Vec<Ty>, ret: Ty, is_varargs: bool) -> CallableSig {
+    pub fn from_params_and_return(
+        mut params: Vec<Ty>,
+        ret: Ty,
+        is_varargs: bool,
+        safety: Safety,
+    ) -> CallableSig {
         params.push(ret);
-        CallableSig { params_and_return: params.into(), is_varargs }
+        CallableSig { params_and_return: params.into(), is_varargs, safety }
     }
 
     pub fn from_fn_ptr(fn_ptr: &FnPointer) -> CallableSig {
@@ -237,13 +243,14 @@ impl CallableSig {
                 .map(|arg| arg.assert_ty_ref(Interner).clone())
                 .collect(),
             is_varargs: fn_ptr.sig.variadic,
+            safety: fn_ptr.sig.safety,
         }
     }
 
     pub fn to_fn_ptr(&self) -> FnPointer {
         FnPointer {
             num_binders: 0,
-            sig: FnSig { abi: (), safety: Safety::Safe, variadic: self.is_varargs },
+            sig: FnSig { abi: (), safety: self.safety, variadic: self.is_varargs },
             substitution: FnSubst(Substitution::from_iter(
                 Interner,
                 self.params_and_return.iter().cloned(),
@@ -268,7 +275,11 @@ impl TypeFoldable<Interner> for CallableSig {
     ) -> Result<Self, E> {
         let vec = self.params_and_return.to_vec();
         let folded = vec.try_fold_with(folder, outer_binder)?;
-        Ok(CallableSig { params_and_return: folded.into(), is_varargs: self.is_varargs })
+        Ok(CallableSig {
+            params_and_return: folded.into(),
+            is_varargs: self.is_varargs,
+            safety: self.safety,
+        })
     }
 }
 
@@ -573,5 +584,5 @@ pub fn callable_sig_from_fnonce(
 
     let ret_ty = db.normalize_projection(projection, env);
 
-    Some(CallableSig::from_params_and_return(params, ret_ty.clone(), false))
+    Some(CallableSig::from_params_and_return(params, ret_ty.clone(), false, Safety::Safe))
 }
diff --git a/crates/hir-ty/src/lower.rs b/crates/hir-ty/src/lower.rs
index 22a85cf1545..baf9842d5fb 100644
--- a/crates/hir-ty/src/lower.rs
+++ b/crates/hir-ty/src/lower.rs
@@ -227,13 +227,17 @@ impl<'a> TyLoweringContext<'a> {
                     .intern(Interner)
             }
             TypeRef::Placeholder => TyKind::Error.intern(Interner),
-            TypeRef::Fn(params, is_varargs) => {
+            &TypeRef::Fn(ref params, variadic, is_unsafe) => {
                 let substs = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
                     Substitution::from_iter(Interner, params.iter().map(|(_, tr)| ctx.lower_ty(tr)))
                 });
                 TyKind::Function(FnPointer {
                     num_binders: 0, // FIXME lower `for<'a> fn()` correctly
-                    sig: FnSig { abi: (), safety: Safety::Safe, variadic: *is_varargs },
+                    sig: FnSig {
+                        abi: (),
+                        safety: if is_unsafe { Safety::Unsafe } else { Safety::Safe },
+                        variadic,
+                    },
                     substitution: FnSubst(substs),
                 })
                 .intern(Interner)
@@ -1573,7 +1577,12 @@ fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
         .with_type_param_mode(ParamLoweringMode::Variable);
     let ret = ctx_ret.lower_ty(&data.ret_type);
     let generics = generics(db.upcast(), def.into());
-    let sig = CallableSig::from_params_and_return(params, ret, data.is_varargs());
+    let sig = CallableSig::from_params_and_return(
+        params,
+        ret,
+        data.is_varargs(),
+        if data.has_unsafe_kw() { Safety::Unsafe } else { Safety::Safe },
+    );
     make_binders(db, &generics, sig)
 }
 
@@ -1617,7 +1626,7 @@ fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnS
         TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable);
     let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
     let (ret, binders) = type_for_adt(db, def.into()).into_value_and_skipped_binders();
-    Binders::new(binders, CallableSig::from_params_and_return(params, ret, false))
+    Binders::new(binders, CallableSig::from_params_and_return(params, ret, false, Safety::Safe))
 }
 
 /// Build the type of a tuple struct constructor.
@@ -1644,7 +1653,7 @@ fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId)
         TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable);
     let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
     let (ret, binders) = type_for_adt(db, def.parent.into()).into_value_and_skipped_binders();
-    Binders::new(binders, CallableSig::from_params_and_return(params, ret, false))
+    Binders::new(binders, CallableSig::from_params_and_return(params, ret, false, Safety::Safe))
 }
 
 /// Build the type of a tuple enum variant constructor.
diff --git a/crates/hir-ty/src/tests/coercion.rs b/crates/hir-ty/src/tests/coercion.rs
index 1abdb0be7f8..7e3aecc2ae0 100644
--- a/crates/hir-ty/src/tests/coercion.rs
+++ b/crates/hir-ty/src/tests/coercion.rs
@@ -390,7 +390,7 @@ fn test() {
     let f: fn(u32) -> isize = foo;
                            // ^^^ adjustments: Pointer(ReifyFnPointer)
     let f: unsafe fn(u32) -> isize = foo;
-                                  // ^^^ adjustments: Pointer(ReifyFnPointer)
+                                  // ^^^ adjustments: Pointer(ReifyFnPointer), Pointer(UnsafeFnPointer)
 }",
     );
 }
@@ -421,7 +421,10 @@ fn coerce_closure_to_fn_ptr() {
     check_no_mismatches(
         r"
 fn test() {
-    let f: fn(u32) -> isize = |x| { 1 };
+    let f: fn(u32) -> u32 = |x| x;
+                         // ^^^^^ adjustments: Pointer(ClosureFnPointer(Safe))
+    let f: unsafe fn(u32) -> u32 = |x| x;
+                                // ^^^^^ adjustments: Pointer(ClosureFnPointer(Unsafe))
 }",
     );
 }