Add not-null pointer patterns to pattern types

Author: oli-obk

compiler/rustc_ast/src/ast.rs

@@ -2484,6 +2484,9 @@ pub enum TyPatKind {
     /// A range pattern (e.g., `1...2`, `1..2`, `1..`, `..2`, `1..=2`, `..=2`).
     Range(Option<P<AnonConst>>, Option<P<AnonConst>>, Spanned<RangeEnd>),
 
+    /// A `!null` pattern for raw pointers.
+    NotNull,
+
     Or(ThinVec<P<TyPat>>),
 
     /// Placeholder for a pattern that wasn't syntactically well formed in some way.

compiler/rustc_ast/src/mut_visit.rs

@@ -560,7 +560,7 @@ pub fn walk_ty_pat<T: MutVisitor>(vis: &mut T, ty: &mut TyPat) {
             visit_opt(end, |c| vis.visit_anon_const(c));
         }
         TyPatKind::Or(variants) => visit_thin_vec(variants, |p| vis.visit_ty_pat(p)),
-        TyPatKind::Err(_) => {}
+        TyPatKind::NotNull | TyPatKind::Err(_) => {}
     }
     vis.visit_span(span);
 }

compiler/rustc_ast/src/visit.rs

@@ -906,7 +906,7 @@ pub fn walk_ty_pat<'a, V: Visitor<'a>>(visitor: &mut V, tp: &'a TyPat) -> V::Res
             visit_opt!(visitor, visit_anon_const, end);
         }
         TyPatKind::Or(variants) => walk_list!(visitor, visit_ty_pat, variants),
-        TyPatKind::Err(_) => {}
+        TyPatKind::NotNull | TyPatKind::Err(_) => {}
     }
     V::Result::output()
 }

compiler/rustc_ast_lowering/src/pat.rs

@@ -143,7 +143,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     }
                     // return inner to be processed in next loop
                     PatKind::Paren(inner) => pattern = inner,
-                    PatKind::MacCall(_) => panic!("{:?} shouldn't exist here", pattern.span),
+                    PatKind::MacCall(_) => {
+                        panic!("{pattern:#?} shouldn't exist here")
+                    }
                     PatKind::Err(guar) => break hir::PatKind::Err(*guar),
                 }
             };
@@ -464,6 +466,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         )
                     }),
             ),
+            TyPatKind::NotNull => hir::TyPatKind::NotNull,
             TyPatKind::Or(variants) => {
                 hir::TyPatKind::Or(self.arena.alloc_from_iter(
                     variants.iter().map(|pat| self.lower_ty_pat_mut(pat, base_type)),

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1218,6 +1218,7 @@ impl<'a> State<'a> {
                     self.print_expr_anon_const(end, &[]);
                 }
             }
+            rustc_ast::TyPatKind::NotNull => self.word("!null"),
             rustc_ast::TyPatKind::Or(variants) => {
                 let mut first = true;
                 for pat in variants {

compiler/rustc_builtin_macros/src/pattern_type.rs

@@ -28,17 +28,23 @@ fn parse_pat_ty<'a>(cx: &mut ExtCtxt<'a>, stream: TokenStream) -> PResult<'a, (P
     let ty = parser.parse_ty()?;
     parser.expect_keyword(exp!(Is))?;
 
-    let pat = pat_to_ty_pat(
-        cx,
-        parser
-            .parse_pat_no_top_guard(
-                None,
-                RecoverComma::No,
-                RecoverColon::No,
-                CommaRecoveryMode::EitherTupleOrPipe,
-            )?
-            .into_inner(),
-    );
+    let start = parser.token.span;
+    let pat = if parser.eat(exp!(Bang)) {
+        parser.expect_keyword(exp!(Null))?;
+        ty_pat(TyPatKind::NotNull, start.to(parser.token.span))
+    } else {
+        pat_to_ty_pat(
+            cx,
+            parser
+                .parse_pat_no_top_guard(
+                    None,
+                    RecoverComma::No,
+                    RecoverColon::No,
+                    CommaRecoveryMode::EitherTupleOrPipe,
+                )?
+                .into_inner(),
+        )
+    };
 
     if parser.token != token::Eof {
         parser.unexpected()?;

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -1248,6 +1248,7 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValueVisitor<'tcx, M> for ValidityVisitor<'rt,
                     // Range patterns are precisely reflected into `valid_range` and thus
                     // handled fully by `visit_scalar` (called below).
                     ty::PatternKind::Range { .. } => {},
+                    ty::PatternKind::NotNull => {},
 
                     // FIXME(pattern_types): check that the value is covered by one of the variants.
                     // For now, we rely on layout computation setting the scalar's `valid_range` to

compiler/rustc_hir/src/hir.rs

@@ -1824,6 +1824,9 @@ pub enum TyPatKind<'hir> {
     /// A range pattern (e.g., `1..=2` or `1..2`).
     Range(&'hir ConstArg<'hir>, &'hir ConstArg<'hir>),
 
+    /// A pattern that excludes null pointers
+    NotNull,
+
     /// A list of patterns where only one needs to be satisfied
     Or(&'hir [TyPat<'hir>]),
 

compiler/rustc_hir/src/intravisit.rs

@@ -711,7 +711,7 @@ pub fn walk_ty_pat<'v, V: Visitor<'v>>(visitor: &mut V, pattern: &'v TyPat<'v>)
             try_visit!(visitor.visit_const_arg_unambig(upper_bound));
         }
         TyPatKind::Or(patterns) => walk_list!(visitor, visit_pattern_type_pattern, patterns),
-        TyPatKind::Err(_) => (),
+        TyPatKind::NotNull | TyPatKind::Err(_) => (),
     }
     V::Result::output()
 }

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -2651,6 +2651,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                         .span_delayed_bug(ty_span, "invalid base type for range pattern")),
                 }
             }
+            hir::TyPatKind::NotNull => Ok(ty::PatternKind::NotNull),
             hir::TyPatKind::Or(patterns) => {
                 self.tcx()
                     .mk_patterns_from_iter(patterns.iter().map(|pat| {