Supporting MethodCall

Author: AlessioC31

clippy_lints/src/redundant_type_annotations.rs

@@ -46,6 +46,27 @@ fn is_same_type<'tcx>(cx: &LateContext<'tcx>, ty_resolved_path: hir::def::Res, f
     false
 }
 
+fn func_hir_id_to_func_ty<'tcx>(cx: &LateContext<'tcx>, hir_id: hir::hir_id::HirId) -> Option<Ty<'tcx>> {
+    if let Some((defkind, func_defid)) = cx.typeck_results().type_dependent_def(hir_id)
+        && defkind == hir::def::DefKind::AssocFn
+        && let Some(init_ty) = cx.tcx.type_of(func_defid).no_bound_vars()
+    {
+        Some(init_ty)
+    } else {
+        None
+    }
+}
+
+fn func_ty_to_return_type<'tcx>(cx: &LateContext<'tcx>, func_ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
+    if func_ty.is_fn()
+        && let Some(return_type) = func_ty.fn_sig(cx.tcx).output().no_bound_vars()
+    {
+        Some(return_type)
+    } else {
+        None
+    }
+}
+
 /// Extracts the fn Ty, e.g. `fn() -> std::string::String {f}`
 fn extract_fn_ty<'tcx>(
     cx: &LateContext<'tcx>,
@@ -66,16 +87,7 @@ fn extract_fn_ty<'tcx>(
         // Associated functions like
         // let a: String = String::new();
         // let a: String = String::get_string();
-        hir::QPath::TypeRelative(..) => {
-            if let Some((defkind, func_defid)) = cx.typeck_results().type_dependent_def(call.hir_id)
-                && defkind == hir::def::DefKind::AssocFn
-                && let Some(init_ty) = cx.tcx.type_of(func_defid).no_bound_vars()
-            {
-                Some(init_ty)
-            } else {
-                None
-            }
-        },
+        hir::QPath::TypeRelative(..) => func_hir_id_to_func_ty(cx, call.hir_id),
         hir::QPath::LangItem(..) => None,
     }
 }
@@ -89,8 +101,7 @@ fn is_redundant_in_func_call<'tcx>(
         let func_type = extract_fn_ty(cx, call, init_path);
 
         if let Some(func_type) = func_type
-            && func_type.is_fn()
-            && let Some(init_return_type) = func_type.fn_sig(cx.tcx).output().no_bound_vars()
+            && let Some(init_return_type) = func_ty_to_return_type(cx, func_type)
         {
             return is_same_type(cx, ty_resolved_path, init_return_type);
         }
@@ -117,8 +128,17 @@ impl LateLintPass<'_> for RedundantTypeAnnotations {
                         span_lint(cx, REDUNDANT_TYPE_ANNOTATIONS, local.span, "redundant type annotation");
                     }
                 },
+                hir::ExprKind::MethodCall(_, _, _, _) => {
+                    if let Some(func_ty) = func_hir_id_to_func_ty(cx, init.hir_id) 
+                        && let Some(return_type) = func_ty_to_return_type(cx, func_ty)
+                        && is_same_type(cx, resolved_path_ty.res, return_type)
+                    {
+                        span_lint(cx, REDUNDANT_TYPE_ANNOTATIONS, local.span, "redundant type annotation");
+                    }
+                },
                 // When the initialization is a path for example u32::MAX
                 hir::ExprKind::Path(init_path) => {
+                    // TODO: check for non primty
                     if let hir::def::Res::PrimTy(primty) = resolved_path_ty.res
 
                         && let hir::QPath::TypeRelative(init_ty, _) = init_path
@@ -130,7 +150,7 @@ impl LateLintPass<'_> for RedundantTypeAnnotations {
                     {
                         span_lint(cx, REDUNDANT_TYPE_ANNOTATIONS, local.span, "redundant type annotation");
                     }
-                }
+                },
                 _ => ()
             }
         };

tests/ui/redundant_type_annotations.rs

@@ -61,7 +61,7 @@ impl Pie {
     }
 
     fn test_method_call(&self) {
-        let v: u32 = self.return_an_int(); // This should lint but doesn't (MethodCall)
+        let v: u32 = self.return_an_int(); // Should lint
     }
 }
 
@@ -130,7 +130,7 @@ fn test_functions() {
 
     let new_pie: Pie = Pie::new();
 
-    let _return: u32 = new_pie.return_an_int(); // this should lint but doesn't (MethodCall)
+    let _return: u32 = new_pie.return_an_int();
 
     let _return: String = String::from("test");
 

tests/ui/redundant_type_annotations.stderr

@@ -1,10 +1,16 @@
+error: redundant type annotation
+  --> $DIR/redundant_type_annotations.rs:64:9
+   |
+LL |         let v: u32 = self.return_an_int(); // Should lint
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::redundant-type-annotations` implied by `-D warnings`
+
 error: redundant type annotation
   --> $DIR/redundant_type_annotations.rs:121:5
    |
 LL |     let _return: String = return_a_string();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `-D clippy::redundant-type-annotations` implied by `-D warnings`
 
 error: redundant type annotation
   --> $DIR/redundant_type_annotations.rs:123:5
@@ -36,6 +42,12 @@ error: redundant type annotation
 LL |     let new_pie: Pie = Pie::new();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error: redundant type annotation
+  --> $DIR/redundant_type_annotations.rs:133:5
+   |
+LL |     let _return: u32 = new_pie.return_an_int();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 error: redundant type annotation
   --> $DIR/redundant_type_annotations.rs:137:5
    |
@@ -54,5 +66,5 @@ error: redundant type annotation
 LL |     let _var: u32 = u32::MAX;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 9 previous errors
+error: aborting due to 11 previous errors