Rollup merge of rust-lang#99119 - TaKO8Ki:remove-string-matching-about-methods, r=cjgillot

Refactor: remove a string matching about methods

This patch remove a string matching about methods and adds some rustfix tests.

Author: Dylan-DPC

compiler/rustc_hir/src/hir.rs

@@ -1824,6 +1824,14 @@ impl Expr<'_> {
             _ => false,
         }
     }
+
+    pub fn method_ident(&self) -> Option<Ident> {
+        match self.kind {
+            ExprKind::MethodCall(receiver_method, ..) => Some(receiver_method.ident),
+            ExprKind::Unary(_, expr) | ExprKind::AddrOf(.., expr) => expr.method_ident(),
+            _ => None,
+        }
+    }
 }
 
 /// Checks if the specified expression is a built-in range literal.

compiler/rustc_span/src/symbol.rs

@@ -1435,6 +1435,8 @@ symbols! {
         thumb2,
         thumb_mode: "thumb-mode",
         tmm_reg,
+        to_string,
+        to_vec,
         todo_macro,
         tool_attributes,
         tool_lints,

compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs

@@ -18,8 +18,6 @@ use rustc_span::symbol::sym;
 use rustc_span::Span;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 
-use std::iter;
-
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     pub(in super::super) fn suggest_semicolon_at_end(&self, span: Span, err: &mut Diagnostic) {
         err.span_suggestion_short(
@@ -187,55 +185,56 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 err.span_label(sp, format!("{found} defined here"));
             }
         } else if !self.check_for_cast(err, expr, found, expected, expected_ty_expr) {
-            let is_struct_pat_shorthand_field =
-                self.maybe_get_struct_pattern_shorthand_field(expr).is_some();
             let methods = self.get_conversion_methods(expr.span, expected, found, expr.hir_id);
             if !methods.is_empty() {
-                if let Ok(expr_text) = self.sess().source_map().span_to_snippet(expr.span) {
-                    let mut suggestions = iter::zip(iter::repeat(&expr_text), &methods)
-                        .filter_map(|(receiver, method)| {
-                            let method_call = format!(".{}()", method.name);
-                            if receiver.ends_with(&method_call) {
-                                None // do not suggest code that is already there (#53348)
-                            } else {
-                                let method_call_list = [".to_vec()", ".to_string()"];
-                                let mut sugg = if receiver.ends_with(".clone()")
-                                    && method_call_list.contains(&method_call.as_str())
-                                {
-                                    let max_len = receiver.rfind('.').unwrap();
-                                    vec![(
-                                        expr.span,
-                                        format!("{}{}", &receiver[..max_len], method_call),
-                                    )]
-                                } else {
-                                    if expr.precedence().order()
-                                        < ExprPrecedence::MethodCall.order()
-                                    {
-                                        vec![
-                                            (expr.span.shrink_to_lo(), "(".to_string()),
-                                            (expr.span.shrink_to_hi(), format!("){}", method_call)),
-                                        ]
-                                    } else {
-                                        vec![(expr.span.shrink_to_hi(), method_call)]
-                                    }
-                                };
-                                if is_struct_pat_shorthand_field {
-                                    sugg.insert(
-                                        0,
-                                        (expr.span.shrink_to_lo(), format!("{}: ", receiver)),
-                                    );
-                                }
-                                Some(sugg)
-                            }
-                        })
-                        .peekable();
-                    if suggestions.peek().is_some() {
-                        err.multipart_suggestions(
-                            "try using a conversion method",
-                            suggestions,
-                            Applicability::MaybeIncorrect,
-                        );
-                    }
+                let mut suggestions = methods.iter()
+                    .filter_map(|conversion_method| {
+                        let receiver_method_ident = expr.method_ident();
+                        if let Some(method_ident) = receiver_method_ident
+                            && method_ident.name == conversion_method.name
+                        {
+                            return None // do not suggest code that is already there (#53348)
+                        }
+
+                        let method_call_list = [sym::to_vec, sym::to_string];
+                        let mut sugg = if let ExprKind::MethodCall(receiver_method, ..) = expr.kind
+                            && receiver_method.ident.name == sym::clone
+                            && method_call_list.contains(&conversion_method.name)
+                            // If receiver is `.clone()` and found type has one of those methods,
+                            // we guess that the user wants to convert from a slice type (`&[]` or `&str`)
+                            // to an owned type (`Vec` or `String`).  These conversions clone internally,
+                            // so we remove the user's `clone` call.
+                        {
+                            vec![(
+                                receiver_method.ident.span,
+                                conversion_method.name.to_string()
+                            )]
+                        } else if expr.precedence().order()
+                            < ExprPrecedence::MethodCall.order()
+                        {
+                            vec![
+                                (expr.span.shrink_to_lo(), "(".to_string()),
+                                (expr.span.shrink_to_hi(), format!(").{}()", conversion_method.name)),
+                            ]
+                        } else {
+                            vec![(expr.span.shrink_to_hi(), format!(".{}()", conversion_method.name))]
+                        };
+                        let struct_pat_shorthand_field = self.maybe_get_struct_pattern_shorthand_field(expr);
+                        if let Some(name) = struct_pat_shorthand_field {
+                            sugg.insert(
+                                0,
+                                (expr.span.shrink_to_lo(), format!("{}: ", name)),
+                            );
+                        }
+                        Some(sugg)
+                    })
+                    .peekable();
+                if suggestions.peek().is_some() {
+                    err.multipart_suggestions(
+                        "try using a conversion method",
+                        suggestions,
+                        Applicability::MaybeIncorrect,
+                    );
                 }
             } else if let ty::Adt(found_adt, found_substs) = found.kind()
                 && self.tcx.is_diagnostic_item(sym::Option, found_adt.did())

src/test/ui/suggestions/issue-52820.fixed

@@ -0,0 +1,15 @@
+// run-rustfix
+#![allow(dead_code)]
+
+struct Bravery {
+    guts: String,
+    brains: String,
+}
+
+fn main() {
+    let guts = "mettle";
+    let _ = Bravery {
+        guts: guts.to_string(), //~ ERROR mismatched types
+        brains: guts.to_string(), //~ ERROR mismatched types
+    };
+}

src/test/ui/suggestions/issue-52820.rs

@@ -1,3 +1,6 @@
+// run-rustfix
+#![allow(dead_code)]
+
 struct Bravery {
     guts: String,
     brains: String,

src/test/ui/suggestions/issue-52820.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/issue-52820.rs:9:9
+  --> $DIR/issue-52820.rs:12:9
    |
 LL |         guts,
    |         ^^^^ expected struct `String`, found `&str`
@@ -10,13 +10,13 @@ LL |         guts: guts.to_string(),
    |         +++++     ++++++++++++
 
 error[E0308]: mismatched types
-  --> $DIR/issue-52820.rs:10:17
+  --> $DIR/issue-52820.rs:13:17
    |
 LL |         brains: guts.clone(),
-   |                 ^^^^^^^^^^^^
-   |                 |
+   |                 ^^^^^-----^^
+   |                 |    |
+   |                 |    help: try using a conversion method: `to_string`
    |                 expected struct `String`, found `&str`
-   |                 help: try using a conversion method: `guts.to_string()`
 
 error: aborting due to 2 previous errors
 

src/test/ui/suggestions/issue-53692.fixed

@@ -0,0 +1,20 @@
+// run-rustfix
+#![allow(unused_variables)]
+
+fn main() {
+    let items = vec![1, 2, 3];
+    let ref_items: &[i32] = &items;
+    let items_clone: Vec<i32> = ref_items.to_vec();
+    //~^ ERROR mismatched types
+
+    // in that case no suggestion will be triggered
+    let items_clone_2: Vec<i32> = items.clone();
+
+    let s = "hi";
+    let string: String = s.to_string();
+    //~^ ERROR mismatched types
+
+    // in that case no suggestion will be triggered
+    let s2 = "hi";
+    let string_2: String = s2.to_string();
+}

src/test/ui/suggestions/issue-53692.rs

@@ -1,17 +1,20 @@
+// run-rustfix
+#![allow(unused_variables)]
+
 fn main() {
-        let items = vec![1, 2, 3];
-        let ref_items: &[i32] = &items;
-        let items_clone: Vec<i32> = ref_items.clone();
-//~^ ERROR mismatched types
+    let items = vec![1, 2, 3];
+    let ref_items: &[i32] = &items;
+    let items_clone: Vec<i32> = ref_items.clone();
+    //~^ ERROR mismatched types
 
-        // in that case no suggestion will be triggered
-        let items_clone_2:Vec<i32> = items.clone();
+    // in that case no suggestion will be triggered
+    let items_clone_2: Vec<i32> = items.clone();
 
-        let s = "hi";
-        let string: String = s.clone();
-//~^ ERROR mismatched types
+    let s = "hi";
+    let string: String = s.clone();
+    //~^ ERROR mismatched types
 
-        // in that case no suggestion will be triggered
-        let s2 = "hi";
-        let string_2: String = s2.to_string();
+    // in that case no suggestion will be triggered
+    let s2 = "hi";
+    let string_2: String = s2.to_string();
 }

src/test/ui/suggestions/issue-53692.stderr

@@ -1,25 +1,25 @@
 error[E0308]: mismatched types
-  --> $DIR/issue-53692.rs:4:37
+  --> $DIR/issue-53692.rs:7:33
    |
-LL |         let items_clone: Vec<i32> = ref_items.clone();
-   |                          --------   ^^^^^^^^^^^^^^^^^
-   |                          |          |
-   |                          |          expected struct `Vec`, found `&[i32]`
-   |                          |          help: try using a conversion method: `ref_items.to_vec()`
-   |                          expected due to this
+LL |     let items_clone: Vec<i32> = ref_items.clone();
+   |                      --------   ^^^^^^^^^^-----^^
+   |                      |          |         |
+   |                      |          |         help: try using a conversion method: `to_vec`
+   |                      |          expected struct `Vec`, found `&[i32]`
+   |                      expected due to this
    |
    = note: expected struct `Vec<i32>`
            found reference `&[i32]`
 
 error[E0308]: mismatched types
-  --> $DIR/issue-53692.rs:11:30
+  --> $DIR/issue-53692.rs:14:26
    |
-LL |         let string: String = s.clone();
-   |                     ------   ^^^^^^^^^
-   |                     |        |
-   |                     |        expected struct `String`, found `&str`
-   |                     |        help: try using a conversion method: `s.to_string()`
-   |                     expected due to this
+LL |     let string: String = s.clone();
+   |                 ------   ^^-----^^
+   |                 |        | |
+   |                 |        | help: try using a conversion method: `to_string`
+   |                 |        expected struct `String`, found `&str`
+   |                 expected due to this
 
 error: aborting due to 2 previous errors