fix rust-lang#101749, use . instead of :: when accessing a method of an object

Author: chenyukang

compiler/rustc_resolve/src/diagnostics.rs

@@ -2004,21 +2004,28 @@ impl<'a> Resolver<'a> {
                             &ribs[ValueNS],
                             ignore_binding,
                         );
-                        println!("res: {:?}", res);
+                        /*           println!("res: {:?}", res);
+                        println!("span: {:?}", ident.span); */
                         let bind = match res {
                             Some(LexicalScopeBinding::Res(Res::Local(id))) => {
                                 Some(*self.pat_span_map.get(&id).unwrap())
                             }
                             _ => None,
                         };
-                        let next = self.next_node_id();
+                        /* let next = self.next_node_id();
                         println!("bind: {:?}", bind);
-                        println!("next: {:?}", next);
-                        if bind.is_some() {
+                        println!("next: {:?}", next); */
+                        let sm = self.session.source_map();
+                        let expand_span =
+                            sm.span_extend_while(ident.span, |c| c == ':').unwrap_or(ident.span);
+                        //println!("expand_span: {:?}", expand_span);
+                        let diff = expand_span.hi() - ident.span.hi();
+                        if let Some(_) = bind && diff == rustc_span::BytePos(2)
+                            {
                             Some((
-                                vec![(bind.unwrap(), String::from(""))],
+                                vec![(expand_span, format!("{}.", ident))],
                                 format!(
-                                    "`{}` is defined here, but is not a crate or module",
+                                    "`{}` is not a crate or module, maybe you meant to call instance method",
                                     ident
                                 ),
                                 Applicability::MaybeIncorrect,

src/test/ui/suggestions/issue-101749.fixed

@@ -0,0 +1,21 @@
+// run-rustfix
+struct Rectangle {
+    width: i32,
+    height: i32,
+}
+impl Rectangle {
+    fn new(width: i32, height: i32) -> Self {
+        Self { width, height }
+    }
+    fn area(&self) -> i32 {
+        self.height * self.width
+    }
+}
+
+fn main() {
+    let width = 3;
+    let height = 4;
+    let rect1 = Rectangle::new(width, height);
+    println!("{}", rect1.area());
+    //~^ ERROR failed to resolve: use of undeclared crate or module
+}

src/test/ui/suggestions/issue-101749.rs

@@ -0,0 +1,21 @@
+// run-rustfix
+struct Rectangle {
+    width: i32,
+    height: i32,
+}
+impl Rectangle {
+    fn new(width: i32, height: i32) -> Self {
+        Self { width, height }
+    }
+    fn area(&self) -> i32 {
+        self.height * self.width
+    }
+}
+
+fn main() {
+    let width = 3;
+    let height = 4;
+    let rect1 = Rectangle::new(width, height);
+    println!("{}", rect1::area());
+    //~^ ERROR failed to resolve: use of undeclared crate or module
+}

src/test/ui/suggestions/issue-101749.stderr

@@ -0,0 +1,14 @@
+error[E0433]: failed to resolve: use of undeclared crate or module `rect1`
+  --> $DIR/issue-101749.rs:19:20
+   |
+LL |     println!("{}", rect1::area());
+   |                    ^^^^^ use of undeclared crate or module `rect1`
+   |
+help: `rect1` is not a crate or module, maybe you meant to call instance method
+   |
+LL |     println!("{}", rect1.area());
+   |                    ~~~~~~
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0433`.