Auto merge of #125077 - spastorino:add-new-fnsafety-enum2, r=jackh726

Rename Unsafe to Safety

Alternative to #124455, which is to just have one Safety enum to use everywhere, this opens the posibility of adding `ast::Safety::Safe` that's useful for unsafe extern blocks.

This leaves us today with:

```rust
enum ast::Safety {
    Unsafe(Span),
    Default,
    // Safe (going to be added for unsafe extern blocks)
}

enum hir::Safety {
    Unsafe,
    Safe,
}
```

We would convert from `ast::Safety::Default` into the right Safety level according the context.

compiler/rustc_builtin_macros/src/alloc_error_handler.rs

@@ -3,7 +3,7 @@ use crate::util::check_builtin_macro_attribute;
 
 use rustc_ast::ptr::P;
 use rustc_ast::{self as ast, FnHeader, FnSig, Generics, StmtKind};
-use rustc_ast::{Fn, ItemKind, Stmt, TyKind, Unsafe};
+use rustc_ast::{Fn, ItemKind, Safety, Stmt, TyKind};
 use rustc_expand::base::{Annotatable, ExtCtxt};
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::Span;
@@ -78,7 +78,7 @@ fn generate_handler(cx: &ExtCtxt<'_>, handler: Ident, span: Span, sig_span: Span
     let never = ast::FnRetTy::Ty(cx.ty(span, TyKind::Never));
     let params = thin_vec![cx.param(span, size, ty_usize.clone()), cx.param(span, align, ty_usize)];
     let decl = cx.fn_decl(params, never);
-    let header = FnHeader { unsafety: Unsafe::Yes(span), ..FnHeader::default() };
+    let header = FnHeader { safety: Safety::Unsafe(span), ..FnHeader::default() };
     let sig = FnSig { decl, header, span: span };
 
     let body = Some(cx.block_expr(call));

compiler/rustc_builtin_macros/src/deriving/generic/mod.rs

@@ -788,7 +788,7 @@ impl<'a> TraitDef<'a> {
             Ident::empty(),
             attrs,
             ast::ItemKind::Impl(Box::new(ast::Impl {
-                unsafety: ast::Unsafe::No,
+                safety: ast::Safety::Default,
                 polarity: ast::ImplPolarity::Positive,
                 defaultness: ast::Defaultness::Final,
                 constness: if self.is_const { ast::Const::Yes(DUMMY_SP) } else { ast::Const::No },

compiler/rustc_builtin_macros/src/global_allocator.rs

@@ -6,7 +6,7 @@ use rustc_ast::expand::allocator::{
 };
 use rustc_ast::ptr::P;
 use rustc_ast::{self as ast, AttrVec, Expr, FnHeader, FnSig, Generics, Param, StmtKind};
-use rustc_ast::{Fn, ItemKind, Mutability, Stmt, Ty, TyKind, Unsafe};
+use rustc_ast::{Fn, ItemKind, Mutability, Safety, Stmt, Ty, TyKind};
 use rustc_expand::base::{Annotatable, ExtCtxt};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::Span;
@@ -73,7 +73,7 @@ impl AllocFnFactory<'_, '_> {
         let result = self.call_allocator(method.name, args);
         let output_ty = self.ret_ty(&method.output);
         let decl = self.cx.fn_decl(abi_args, ast::FnRetTy::Ty(output_ty));
-        let header = FnHeader { unsafety: Unsafe::Yes(self.span), ..FnHeader::default() };
+        let header = FnHeader { safety: Safety::Unsafe(self.span), ..FnHeader::default() };
         let sig = FnSig { decl, header, span: self.span };
         let body = Some(self.cx.block_expr(result));
         let kind = ItemKind::Fn(Box::new(Fn {

compiler/rustc_builtin_macros/src/test.rs

@@ -549,7 +549,7 @@ fn check_test_signature(
     let has_should_panic_attr = attr::contains_name(&i.attrs, sym::should_panic);
     let dcx = cx.dcx();
 
-    if let ast::Unsafe::Yes(span) = f.sig.header.unsafety {
+    if let ast::Safety::Unsafe(span) = f.sig.header.safety {
         return Err(dcx.emit_err(errors::TestBadFn { span: i.span, cause: span, kind: "unsafe" }));
     }