Handle safe safety keyword for fns (not yet ready, generated unsafe…

… fns)

compiler/rustc_ast/src/ast.rs

@@ -2489,6 +2489,7 @@ pub enum Unsafe {
 #[derive(HashStable_Generic)]
 pub enum FnSafety {
     Unsafe(Span),
+    Safe(Span),
     Default,
 }
 

compiler/rustc_ast/src/mut_visit.rs

@@ -867,6 +867,7 @@ fn visit_unsafety<T: MutVisitor>(unsafety: &mut Unsafe, vis: &mut T) {
 fn visit_fn_safety<T: MutVisitor>(safety: &mut FnSafety, vis: &mut T) {
     match safety {
         FnSafety::Unsafe(span) => vis.visit_span(span),
+        FnSafety::Safe(span) => vis.visit_span(span),
         FnSafety::Default => {}
     }
 }

compiler/rustc_ast/src/token.rs

@@ -210,6 +210,7 @@ pub fn ident_can_begin_expr(name: Symbol, span: Span, is_raw: IdentIsRaw) -> boo
             kw::Unsafe,
             kw::While,
             kw::Yield,
+            kw::Safe,
             kw::Static,
         ]
         .contains(&name)
@@ -563,6 +564,7 @@ impl Token {
                 kw::Impl,
                 kw::Unsafe,
                 kw::Const,
+                kw::Safe,
                 kw::Static,
                 kw::Union,
                 kw::Macro,

compiler/rustc_ast_lowering/src/item.rs

@@ -1411,6 +1411,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     pub(super) fn lower_fn_safety(&mut self, u: FnSafety) -> hir::FnSafety {
         match u {
             FnSafety::Unsafe(_) => hir::FnSafety::Unsafe,
+            FnSafety::Safe(_) => hir::FnSafety::Safe,
             FnSafety::Default => hir::FnSafety::Default,
         }
     }

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1943,6 +1943,7 @@ impl<'a> State<'a> {
     fn print_fn_safety(&mut self, s: ast::FnSafety) {
         match s {
             ast::FnSafety::Default => {}
+            ast::FnSafety::Safe(_) => self.word_nbsp("safe"),
             ast::FnSafety::Unsafe(_) => self.word_nbsp("unsafe"),
         }
     }

compiler/rustc_hir/src/hir.rs

@@ -3208,13 +3208,15 @@ impl fmt::Display for Unsafety {
 #[derive(Encodable, Decodable, HashStable_Generic)]
 pub enum FnSafety {
     Unsafe,
+    Safe,
     Default,
 }
 
 impl FnSafety {
     pub fn prefix_str(&self) -> &'static str {
         match self {
             Self::Unsafe => "unsafe ",
+            Self::Safe => "safe ",
             Self::Default => "",
         }
     }
@@ -3224,6 +3226,7 @@ impl fmt::Display for FnSafety {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str(match *self {
             Self::Unsafe => "unsafe",
+            Self::Safe => "safe",
             Self::Default => "normal",
         })
     }

compiler/rustc_hir_pretty/src/lib.rs

@@ -2290,6 +2290,7 @@ impl<'a> State<'a> {
     fn print_fn_safety(&mut self, s: hir::FnSafety) {
         match s {
             hir::FnSafety::Default => {}
+            hir::FnSafety::Safe => self.word_nbsp("safe"),
             hir::FnSafety::Unsafe => self.word_nbsp("unsafe"),
         }
     }

compiler/rustc_parse/src/parser/item.rs

@@ -2376,9 +2376,9 @@ impl<'a> Parser<'a> {
         // `pub` is added in case users got confused with the ordering like `async pub fn`,
         // only if it wasn't preceded by `default` as `default pub` is invalid.
         let quals: &[Symbol] = if check_pub {
-            &[kw::Pub, kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Extern]
+            &[kw::Pub, kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Safe, kw::Extern]
         } else {
-            &[kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Extern]
+            &[kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Safe, kw::Extern]
         };
         self.check_keyword_case(kw::Fn, case) // Definitely an `fn`.
             // `$qual fn` or `$qual $qual`:
@@ -2513,11 +2513,27 @@ impl<'a> Parser<'a> {
                     } else if self.check_keyword(kw::Unsafe) {
                         match safety {
                             FnSafety::Unsafe(sp) => Some(WrongKw::Duplicated(sp)),
+                            FnSafety::Safe(sp) => {
+                                recover_safety = FnSafety::Unsafe(self.token.span);
+                                Some(WrongKw::Misplaced(sp))
+                            }
                             FnSafety::Default => {
                                 recover_safety = FnSafety::Unsafe(self.token.span);
                                 Some(WrongKw::Misplaced(ext_start_sp))
                             }
                         }
+                    } else if self.check_keyword(kw::Safe) {
+                        match safety {
+                            FnSafety::Safe(sp) => Some(WrongKw::Duplicated(sp)),
+                            FnSafety::Unsafe(sp) => {
+                                recover_safety = FnSafety::Safe(self.token.span);
+                                Some(WrongKw::Misplaced(sp))
+                            }
+                            FnSafety::Default => {
+                                recover_safety = FnSafety::Safe(self.token.span);
+                                Some(WrongKw::Misplaced(ext_start_sp))
+                            }
+                        }
                     } else {
                         None
                     };

compiler/rustc_parse/src/parser/mod.rs

@@ -1225,6 +1225,8 @@ impl<'a> Parser<'a> {
     fn parse_fn_safety(&mut self, case: Case) -> FnSafety {
         if self.eat_keyword_case(kw::Unsafe, case) {
             FnSafety::Unsafe(self.prev_token.uninterpolated_span())
+        } else if self.eat_keyword_case(kw::Safe, case) {
+            FnSafety::Safe(self.prev_token.uninterpolated_span())
         } else {
             FnSafety::Default
         }

compiler/rustc_smir/src/rustc_internal/internal.rs

@@ -497,6 +497,7 @@ impl RustcInternal for FnSafety {
     fn internal<'tcx>(&self, _tables: &mut Tables<'_>, _tcx: TyCtxt<'tcx>) -> Self::T<'tcx> {
         match self {
             FnSafety::Unsafe => rustc_hir::FnSafety::Unsafe,
+            FnSafety::Safe => rustc_hir::FnSafety::Safe,
             FnSafety::Default => rustc_hir::FnSafety::Default,
         }
     }

compiler/rustc_smir/src/rustc_smir/convert/mod.rs

@@ -24,6 +24,7 @@ impl<'tcx> Stable<'tcx> for rustc_hir::FnSafety {
     fn stable(&self, _: &mut Tables<'_>) -> Self::T {
         match self {
             rustc_hir::FnSafety::Unsafe => stable_mir::mir::FnSafety::Unsafe,
+            rustc_hir::FnSafety::Safe => stable_mir::mir::FnSafety::Safe,
             rustc_hir::FnSafety::Default => stable_mir::mir::FnSafety::Default,
         }
     }

compiler/rustc_span/src/symbol.rs

@@ -103,6 +103,7 @@ symbols! {
         MacroRules:         "macro_rules",
         Raw:                "raw",
         Reuse:              "reuse",
+        Safe:               "safe",
         Union:              "union",
         Yeet:               "yeet",
     }

compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs

@@ -204,6 +204,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 let fn_sig = self_ty.fn_sig(self.tcx);
                 let shortname = match fn_sig.safety() {
                     hir::FnSafety::Default => "fn",
+                    hir::FnSafety::Safe => "safe fn",
                     hir::FnSafety::Unsafe => "unsafe fn",
                 };
                 flags.push((sym::_Self, Some(shortname.to_owned())));

compiler/stable_mir/src/mir/body.rs

@@ -922,6 +922,7 @@ pub enum Safety {
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum FnSafety {
     Unsafe,
+    Safe,
     Default,
 }
 

tests/ui/async-await/no-async-const.rs

@@ -2,5 +2,5 @@
 //@ compile-flags: --crate-type lib
 
 pub async const fn x() {}
-//~^ ERROR expected one of `extern`, `fn`, or `unsafe`, found keyword `const`
+//~^ ERROR expected one of `extern`, `fn`, `safe`, or `unsafe`, found keyword `const`
 //~| ERROR functions cannot be both `const` and `async`

tests/ui/async-await/no-async-const.stderr

@@ -1,10 +1,10 @@
-error: expected one of `extern`, `fn`, or `unsafe`, found keyword `const`
+error: expected one of `extern`, `fn`, `safe`, or `unsafe`, found keyword `const`
   --> $DIR/no-async-const.rs:4:11
    |
 LL | pub async const fn x() {}
    |     ------^^^^^
    |     |     |
-   |     |     expected one of `extern`, `fn`, or `unsafe`
+   |     |     expected one of `extern`, `fn`, `safe`, or `unsafe`
    |     help: `const` must come before `async`: `const async`
    |
    = note: keyword order for functions declaration is `pub`, `default`, `const`, `async`, `unsafe`, `extern`

tests/ui/coroutine/async_gen_fn.none.stderr

@@ -7,11 +7,11 @@ LL | async gen fn foo() {}
    = help: pass `--edition 2021` to `rustc`
    = note: for more on editions, read https://doc.rust-lang.org/edition-guide
 
-error: expected one of `extern`, `fn`, or `unsafe`, found `gen`
+error: expected one of `extern`, `fn`, `safe`, or `unsafe`, found `gen`
   --> $DIR/async_gen_fn.rs:4:7
    |
 LL | async gen fn foo() {}
-   |       ^^^ expected one of `extern`, `fn`, or `unsafe`
+   |       ^^^ expected one of `extern`, `fn`, `safe`, or `unsafe`
 
 error: aborting due to 2 previous errors
 

tests/ui/coroutine/async_gen_fn.rs

@@ -3,7 +3,7 @@
 
 async gen fn foo() {}
 //[none]~^ ERROR: `async fn` is not permitted in Rust 2015
-//[none]~| ERROR: expected one of `extern`, `fn`, or `unsafe`, found `gen`
+//[none]~| ERROR: expected one of `extern`, `fn`, `safe`, or `unsafe`, found `gen`
 //[e2024]~^^^ ERROR: gen blocks are experimental
 
 fn main() {}

tests/ui/coroutine/gen_fn.none.stderr

@@ -1,8 +1,8 @@
-error: expected one of `#`, `async`, `const`, `default`, `extern`, `fn`, `pub`, `unsafe`, or `use`, found `gen`
+error: expected one of `#`, `async`, `const`, `default`, `extern`, `fn`, `pub`, `safe`, `unsafe`, or `use`, found `gen`
   --> $DIR/gen_fn.rs:4:1
    |
 LL | gen fn foo() {}
-   | ^^^ expected one of 9 possible tokens
+   | ^^^ expected one of 10 possible tokens
 
 error: aborting due to 1 previous error
 

tests/ui/coroutine/gen_fn.rs

@@ -2,7 +2,7 @@
 //@[e2024] compile-flags: --edition 2024 -Zunstable-options
 
 gen fn foo() {}
-//[none]~^ ERROR: expected one of `#`, `async`, `const`, `default`, `extern`, `fn`, `pub`, `unsafe`, or `use`, found `gen`
+//[none]~^ ERROR: expected one of `#`, `async`, `const`, `default`, `extern`, `fn`, `pub`, `safe`, `unsafe`, or `use`, found `gen`
 //[e2024]~^^ ERROR: gen blocks are experimental
 
 fn main() {}

tests/ui/parser/duplicate-visibility.rs

@@ -2,8 +2,8 @@ fn main() {}
 
 extern "C" { //~ NOTE while parsing this item list starting here
     pub pub fn foo();
-    //~^ ERROR expected one of `(`, `async`, `const`, `default`, `extern`, `fn`, `unsafe`, or `use`, found keyword `pub`
-    //~| NOTE expected one of 8 possible tokens
+    //~^ ERROR expected one of `(`, `async`, `const`, `default`, `extern`, `fn`, `safe`, `unsafe`, or `use`, found keyword `pub`
+    //~| NOTE expected one of 9 possible tokens
     //~| HELP there is already a visibility modifier, remove one
     //~| NOTE explicit visibility first seen here
 } //~ NOTE the item list ends here

tests/ui/parser/duplicate-visibility.stderr

@@ -1,12 +1,12 @@
-error: expected one of `(`, `async`, `const`, `default`, `extern`, `fn`, `unsafe`, or `use`, found keyword `pub`
+error: expected one of `(`, `async`, `const`, `default`, `extern`, `fn`, `safe`, `unsafe`, or `use`, found keyword `pub`
   --> $DIR/duplicate-visibility.rs:4:9
    |
 LL | extern "C" {
    |            - while parsing this item list starting here
 LL |     pub pub fn foo();
    |         ^^^
    |         |
-   |         expected one of 8 possible tokens
+   |         expected one of 9 possible tokens
    |         help: there is already a visibility modifier, remove one
 ...
 LL | }

tests/ui/parser/issues/issue-76437-async.rs

@@ -2,6 +2,6 @@
 
 mod t {
     async pub fn t() {}
-    //~^ ERROR expected one of `extern`, `fn`, or `unsafe`, found keyword `pub`
+    //~^ ERROR expected one of `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
     //~| HELP visibility `pub` must come before `async`
 }

tests/ui/parser/issues/issue-76437-async.stderr

@@ -1,10 +1,10 @@
-error: expected one of `extern`, `fn`, or `unsafe`, found keyword `pub`
+error: expected one of `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
   --> $DIR/issue-76437-async.rs:4:11
    |
 LL |     async pub fn t() {}
    |     ------^^^
    |     |     |
-   |     |     expected one of `extern`, `fn`, or `unsafe`
+   |     |     expected one of `extern`, `fn`, `safe`, or `unsafe`
    |     help: visibility `pub` must come before `async`: `pub async`
 
 error: aborting due to 1 previous error

tests/ui/parser/issues/issue-76437-const-async.rs

@@ -2,6 +2,6 @@
 
 mod t {
     const async pub fn t() {}
-    //~^ ERROR expected one of `extern`, `fn`, or `unsafe`, found keyword `pub`
+    //~^ ERROR expected one of `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
     //~| HELP visibility `pub` must come before `const async`
 }

tests/ui/parser/issues/issue-76437-const-async.stderr

@@ -1,10 +1,10 @@
-error: expected one of `extern`, `fn`, or `unsafe`, found keyword `pub`
+error: expected one of `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
   --> $DIR/issue-76437-const-async.rs:4:17
    |
 LL |     const async pub fn t() {}
    |     ------------^^^
    |     |           |
-   |     |           expected one of `extern`, `fn`, or `unsafe`
+   |     |           expected one of `extern`, `fn`, `safe`, or `unsafe`
    |     help: visibility `pub` must come before `const async`: `pub const async`
 
 error: aborting due to 1 previous error

tests/ui/parser/issues/issue-76437-const.rs

@@ -2,6 +2,6 @@
 
 mod t {
     const pub fn t() {}
-    //~^ ERROR expected one of `async`, `extern`, `fn`, or `unsafe`, found keyword `pub`
+    //~^ ERROR expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
     //~| HELP visibility `pub` must come before `const`
 }

tests/ui/parser/issues/issue-76437-const.stderr

@@ -1,10 +1,10 @@
-error: expected one of `async`, `extern`, `fn`, or `unsafe`, found keyword `pub`
+error: expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
   --> $DIR/issue-76437-const.rs:4:11
    |
 LL |     const pub fn t() {}
    |     ------^^^
    |     |     |
-   |     |     expected one of `async`, `extern`, `fn`, or `unsafe`
+   |     |     expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`
    |     help: visibility `pub` must come before `const`: `pub const`
 
 error: aborting due to 1 previous error

tests/ui/parser/issues/issue-86895.rs

@@ -1,3 +1,3 @@
 const pub () {}
-//~^ ERROR expected one of `async`, `extern`, `fn`, or `unsafe`
+//~^ ERROR expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`
 pub fn main() {}

tests/ui/parser/issues/issue-86895.stderr

@@ -1,8 +1,8 @@
-error: expected one of `async`, `extern`, `fn`, or `unsafe`, found keyword `pub`
+error: expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
   --> $DIR/issue-86895.rs:1:7
    |
 LL | const pub () {}
-   |       ^^^ expected one of `async`, `extern`, `fn`, or `unsafe`
+   |       ^^^ expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`
 
 error: aborting due to 1 previous error
 

tests/ui/parser/issues/issue-87217-keyword-order/const-async-const.rs

@@ -3,8 +3,8 @@
 // Test that even when `const` is already present, the proposed fix is to remove the second `const`
 
 const async const fn test() {}
-//~^ ERROR expected one of `extern`, `fn`, or `unsafe`, found keyword `const`
-//~| NOTE expected one of `extern`, `fn`, or `unsafe`
+//~^ ERROR expected one of `extern`, `fn`, `safe`, or `unsafe`, found keyword `const`
+//~| NOTE expected one of `extern`, `fn`, `safe`, or `unsafe`
 //~| HELP `const` already used earlier, remove this one
 //~| NOTE `const` first seen here
 //~| ERROR functions cannot be both `const` and `async`

tests/ui/parser/issues/issue-87217-keyword-order/const-async-const.stderr

@@ -1,10 +1,10 @@
-error: expected one of `extern`, `fn`, or `unsafe`, found keyword `const`
+error: expected one of `extern`, `fn`, `safe`, or `unsafe`, found keyword `const`
   --> $DIR/const-async-const.rs:5:13
    |
 LL | const async const fn test() {}
    |             ^^^^^
    |             |
-   |             expected one of `extern`, `fn`, or `unsafe`
+   |             expected one of `extern`, `fn`, `safe`, or `unsafe`
    |             help: `const` already used earlier, remove this one
    |
 note: `const` first seen here

tests/ui/parser/issues/issue-87694-duplicated-pub.rs

@@ -1,5 +1,5 @@
 pub const pub fn test() {}
-//~^ ERROR expected one of `async`, `extern`, `fn`, or `unsafe`, found keyword `pub`
-//~| NOTE expected one of `async`, `extern`, `fn`, or `unsafe`
+//~^ ERROR expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
+//~| NOTE expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`
 //~| HELP there is already a visibility modifier, remove one
 //~| NOTE explicit visibility first seen here

tests/ui/parser/issues/issue-87694-duplicated-pub.stderr

@@ -1,10 +1,10 @@
-error: expected one of `async`, `extern`, `fn`, or `unsafe`, found keyword `pub`
+error: expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
   --> $DIR/issue-87694-duplicated-pub.rs:1:11
    |
 LL | pub const pub fn test() {}
    |           ^^^
    |           |
-   |           expected one of `async`, `extern`, `fn`, or `unsafe`
+   |           expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`
    |           help: there is already a visibility modifier, remove one
    |
 note: explicit visibility first seen here

tests/ui/parser/issues/issue-87694-misplaced-pub.rs

@@ -1,5 +1,5 @@
 const pub fn test() {}
-//~^ ERROR expected one of `async`, `extern`, `fn`, or `unsafe`, found keyword `pub`
-//~| NOTE expected one of `async`, `extern`, `fn`, or `unsafe`
+//~^ ERROR expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`, found keyword `pub`
+//~| NOTE expected one of `async`, `extern`, `fn`, `safe`, or `unsafe`
 //~| HELP visibility `pub` must come before `const`
 //~| SUGGESTION pub const