Give correct suggestion for a typo in raw pointers

compiler/rustc_parse/src/parser/ty.rs

@@ -276,6 +276,34 @@ impl<'a> Parser<'a> {
     ) -> PResult<'a, Box<Ty>> {
         let allow_qpath_recovery = recover_qpath == RecoverQPath::Yes;
         maybe_recover_from_interpolated_ty_qpath!(self, allow_qpath_recovery);
+
+        if (self.token.is_keyword(kw::Const) || self.token.is_keyword(kw::Mut))
+            && self.look_ahead(1, |t| *t == token::Star)
+        {
+            let kw_span = self.token.span;
+            self.bump();
+
+            if self.eat(exp!(Star)) {
+                let star_span = self.prev_token.span;
+
+                let _ = self.parse_ty_no_question_mark_recover();
+
+                let guar = self
+                    .dcx()
+                    .struct_span_err(
+                        kw_span,
+                        "raw pointer type must have a star before the mutability keyword",
+                    )
+                    .with_multipart_suggestion(
+                        "move it to the other side",
+                        vec![(star_span, String::new()), (kw_span.shrink_to_lo(), "*".to_string())],
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+
+                return Ok(self.mk_ty(kw_span.to(star_span), TyKind::Err(guar)));
+            }
+        }
         if self.token == token::Pound && self.look_ahead(1, |t| *t == token::OpenBracket) {
             let attrs_wrapper = self.parse_outer_attributes()?;
             let raw_attrs = attrs_wrapper.take_for_recovery(self.psess);

tests/ui/did_you_mean/c-style-pointer-types.fixed

@@ -0,0 +1,113 @@
+//@ run-rustfix
+
+#![allow(unused)]
+
+pub const P1: *const u8 = 0 as _;
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P2: *mut u8 = 1 as _;
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P3: *const i32 = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P4: *const i32 = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P5: *mut i32 = std::ptr::null_mut();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P6: *mut i32 = std::ptr::null_mut();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P7: *const Vec<u8> = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P8: *const std::collections::HashMap<String, i32> = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn func1(p: *const u8) {}
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn func2(p: *mut u8) {}
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn func3() -> *const u8 { std::ptr::null() }
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn func4() -> *mut u8 { std::ptr::null_mut() }
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+struct S1 {
+    field: *const u8,
+    //~^ ERROR: raw pointer type must have a star before the mutability keyword
+    //~| HELP: move it to the other side
+}
+
+struct S2 {
+    field: *mut u8,
+    //~^ ERROR: raw pointer type must have a star before the mutability keyword
+    //~| HELP: move it to the other side
+}
+
+type Tuple1 = (*const u8, i32);
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Tuple2 = (*mut u8, i32);
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Array1 = [*const u8; 10];
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Array2 = [*mut u8; 10];
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Alias1 = *const u8;
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Alias2 = *mut u8;
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P9: *const u8 = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P10: *const    u8 = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+impl S1 {
+    fn method(self, size: *const u32) {}
+    //~^ ERROR: raw pointer type must have a star before the mutability keyword
+    //~| HELP: move it to the other side
+}
+
+trait Trait1 {
+    fn method(p: *const u8);
+    //~^ ERROR: raw pointer type must have a star before the mutability keyword
+    //~| HELP: move it to the other side
+}
+
+fn generic_func<T>() -> *const T { std::ptr::null() }
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn main() {}

tests/ui/did_you_mean/c-style-pointer-types.rs

@@ -0,0 +1,113 @@
+//@ run-rustfix
+
+#![allow(unused)]
+
+pub const P1: const* u8 = 0 as _;
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P2: mut* u8 = 1 as _;
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P3: const* i32 = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P4: const* i32 = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P5: mut* i32 = std::ptr::null_mut();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P6: mut* i32 = std::ptr::null_mut();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P7: const* Vec<u8> = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P8: const* std::collections::HashMap<String, i32> = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn func1(p: const* u8) {}
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn func2(p: mut* u8) {}
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn func3() -> const* u8 { std::ptr::null() }
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn func4() -> mut* u8 { std::ptr::null_mut() }
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+struct S1 {
+    field: const* u8,
+    //~^ ERROR: raw pointer type must have a star before the mutability keyword
+    //~| HELP: move it to the other side
+}
+
+struct S2 {
+    field: mut* u8,
+    //~^ ERROR: raw pointer type must have a star before the mutability keyword
+    //~| HELP: move it to the other side
+}
+
+type Tuple1 = (const* u8, i32);
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Tuple2 = (mut* u8, i32);
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Array1 = [const* u8; 10];
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Array2 = [mut* u8; 10];
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Alias1 = const* u8;
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+type Alias2 = mut* u8;
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P9: const *u8 = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+pub const P10: const  *  u8 = std::ptr::null();
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+impl S1 {
+    fn method(self, size: const* u32) {}
+    //~^ ERROR: raw pointer type must have a star before the mutability keyword
+    //~| HELP: move it to the other side
+}
+
+trait Trait1 {
+    fn method(p: const* u8);
+    //~^ ERROR: raw pointer type must have a star before the mutability keyword
+    //~| HELP: move it to the other side
+}
+
+fn generic_func<T>() -> const* T { std::ptr::null() }
+//~^ ERROR: raw pointer type must have a star before the mutability keyword
+//~| HELP: move it to the other side
+
+fn main() {}