Auto merge of rust-lang#5032 - JohnTitor:add-sugg-some-result, r=flip1995

Add suggestions for `if_let_some_result`

Fixes rust-lang#4991

This approach may be fragile though...

changelog: Add suggestions for `if_let_some_result`

Author: bors

clippy_lints/src/ok_if_let.rs renamed to clippy_lints/src/if_let_some_result.rs

@@ -1,5 +1,6 @@
-use crate::utils::{match_type, method_chain_args, paths, snippet, span_help_and_lint};
+use crate::utils::{match_type, method_chain_args, paths, snippet_with_applicability, span_lint_and_sugg};
 use if_chain::if_chain;
+use rustc_errors::Applicability;
 use rustc_hir::*;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -39,20 +40,32 @@ declare_lint_pass!(OkIfLet => [IF_LET_SOME_RESULT]);
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for OkIfLet {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! { //begin checking variables
-            if let ExprKind::Match(ref op, ref body, ref source) = expr.kind; //test if expr is a match
-            if let MatchSource::IfLetDesugar { .. } = *source; //test if it is an If Let
-            if let ExprKind::MethodCall(_, _, ref result_types) = op.kind; //check is expr.ok() has type Result<T,E>.ok()
+            if let ExprKind::Match(ref op, ref body, source) = expr.kind; //test if expr is a match
+            if let MatchSource::IfLetDesugar { .. } = source; //test if it is an If Let
+            if let ExprKind::MethodCall(_, ok_span, ref result_types) = op.kind; //check is expr.ok() has type Result<T,E>.ok()
             if let PatKind::TupleStruct(QPath::Resolved(_, ref x), ref y, _)  = body[0].pat.kind; //get operation
             if method_chain_args(op, &["ok"]).is_some(); //test to see if using ok() methoduse std::marker::Sized;
+            let is_result_type = match_type(cx, cx.tables.expr_ty(&result_types[0]), &paths::RESULT);
+            if print::to_string(print::NO_ANN, |s| s.print_path(x, false)) == "Some" && is_result_type;
 
             then {
-                let is_result_type = match_type(cx, cx.tables.expr_ty(&result_types[0]), &paths::RESULT);
-                let some_expr_string = snippet(cx, y[0].span, "");
-                if print::to_string(print::NO_ANN, |s| s.print_path(x, false)) == "Some" && is_result_type {
-                    span_help_and_lint(cx, IF_LET_SOME_RESULT, expr.span,
+                let mut applicability = Applicability::MachineApplicable;
+                let some_expr_string = snippet_with_applicability(cx, y[0].span, "", &mut applicability);
+                let trimmed_ok = snippet_with_applicability(cx, op.span.until(ok_span), "", &mut applicability);
+                let sugg = format!(
+                    "if let Ok({}) = {}",
+                    some_expr_string,
+                    trimmed_ok.trim().trim_end_matches('.'),
+                );
+                span_lint_and_sugg(
+                    cx,
+                    IF_LET_SOME_RESULT,
+                    expr.span.with_hi(op.span.hi()),
                     "Matching on `Some` with `ok()` is redundant",
-                    &format!("Consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string));
-                }
+                    &format!("Consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string),
+                    sugg,
+                    applicability,
+                );
             }
         }
     }

clippy_lints/src/lib.rs

@@ -210,6 +210,7 @@ pub mod functions;
 pub mod get_last_with_len;
 pub mod identity_conversion;
 pub mod identity_op;
+pub mod if_let_some_result;
 pub mod if_not_else;
 pub mod implicit_return;
 pub mod indexing_slicing;
@@ -263,7 +264,6 @@ pub mod new_without_default;
 pub mod no_effect;
 pub mod non_copy_const;
 pub mod non_expressive_names;
-pub mod ok_if_let;
 pub mod open_options;
 pub mod overflow_check_conditional;
 pub mod panic_unimplemented;
@@ -545,6 +545,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &get_last_with_len::GET_LAST_WITH_LEN,
         &identity_conversion::IDENTITY_CONVERSION,
         &identity_op::IDENTITY_OP,
+        &if_let_some_result::IF_LET_SOME_RESULT,
         &if_not_else::IF_NOT_ELSE,
         &implicit_return::IMPLICIT_RETURN,
         &indexing_slicing::INDEXING_SLICING,
@@ -703,7 +704,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &non_expressive_names::JUST_UNDERSCORES_AND_DIGITS,
         &non_expressive_names::MANY_SINGLE_CHAR_NAMES,
         &non_expressive_names::SIMILAR_NAMES,
-        &ok_if_let::IF_LET_SOME_RESULT,
         &open_options::NONSENSICAL_OPEN_OPTIONS,
         &overflow_check_conditional::OVERFLOW_CHECK_CONDITIONAL,
         &panic_unimplemented::PANIC,
@@ -904,7 +904,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box eval_order_dependence::EvalOrderDependence);
     store.register_late_pass(|| box missing_doc::MissingDoc::new());
     store.register_late_pass(|| box missing_inline::MissingInline);
-    store.register_late_pass(|| box ok_if_let::OkIfLet);
+    store.register_late_pass(|| box if_let_some_result::OkIfLet);
     store.register_late_pass(|| box redundant_pattern_matching::RedundantPatternMatching);
     store.register_late_pass(|| box partialeq_ne_impl::PartialEqNeImpl);
     store.register_late_pass(|| box unused_io_amount::UnusedIoAmount);
@@ -1153,6 +1153,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&get_last_with_len::GET_LAST_WITH_LEN),
         LintId::of(&identity_conversion::IDENTITY_CONVERSION),
         LintId::of(&identity_op::IDENTITY_OP),
+        LintId::of(&if_let_some_result::IF_LET_SOME_RESULT),
         LintId::of(&indexing_slicing::OUT_OF_BOUNDS_INDEXING),
         LintId::of(&infallible_destructuring_match::INFALLIBLE_DESTRUCTURING_MATCH),
         LintId::of(&infinite_iter::INFINITE_ITER),
@@ -1265,7 +1266,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&non_copy_const::DECLARE_INTERIOR_MUTABLE_CONST),
         LintId::of(&non_expressive_names::JUST_UNDERSCORES_AND_DIGITS),
         LintId::of(&non_expressive_names::MANY_SINGLE_CHAR_NAMES),
-        LintId::of(&ok_if_let::IF_LET_SOME_RESULT),
         LintId::of(&open_options::NONSENSICAL_OPEN_OPTIONS),
         LintId::of(&overflow_check_conditional::OVERFLOW_CHECK_CONDITIONAL),
         LintId::of(&panic_unimplemented::PANIC_PARAMS),
@@ -1367,6 +1367,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&formatting::SUSPICIOUS_UNARY_OP_FORMATTING),
         LintId::of(&functions::DOUBLE_MUST_USE),
         LintId::of(&functions::MUST_USE_UNIT),
+        LintId::of(&if_let_some_result::IF_LET_SOME_RESULT),
         LintId::of(&infallible_destructuring_match::INFALLIBLE_DESTRUCTURING_MATCH),
         LintId::of(&inherent_to_string::INHERENT_TO_STRING),
         LintId::of(&len_zero::LEN_WITHOUT_IS_EMPTY),
@@ -1413,7 +1414,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&new_without_default::NEW_WITHOUT_DEFAULT),
         LintId::of(&non_expressive_names::JUST_UNDERSCORES_AND_DIGITS),
         LintId::of(&non_expressive_names::MANY_SINGLE_CHAR_NAMES),
-        LintId::of(&ok_if_let::IF_LET_SOME_RESULT),
         LintId::of(&panic_unimplemented::PANIC_PARAMS),
         LintId::of(&ptr::CMP_NULL),
         LintId::of(&ptr::PTR_ARG),

src/lintlist/mod.rs

@@ -705,7 +705,7 @@ pub const ALL_LINTS: [Lint; 347] = [
         group: "style",
         desc: "usage of `ok()` in `if let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead",
         deprecation: None,
-        module: "ok_if_let",
+        module: "if_let_some_result",
     },
     Lint {
         name: "if_not_else",

tests/ui/if_let_some_result.fixed

@@ -0,0 +1,35 @@
+// run-rustfix
+
+#![warn(clippy::if_let_some_result)]
+
+fn str_to_int(x: &str) -> i32 {
+    if let Ok(y) = x.parse() {
+        y
+    } else {
+        0
+    }
+}
+
+fn str_to_int_ok(x: &str) -> i32 {
+    if let Ok(y) = x.parse() {
+        y
+    } else {
+        0
+    }
+}
+
+#[rustfmt::skip]
+fn strange_some_no_else(x: &str) -> i32 {
+    {
+        if let Ok(y) = x   .   parse()       {
+            return y;
+        };
+        0
+    }
+}
+
+fn main() {
+    let _ = str_to_int("1");
+    let _ = str_to_int_ok("2");
+    let _ = strange_some_no_else("3");
+}

tests/ui/if_let_some_result.rs

@@ -0,0 +1,35 @@
+// run-rustfix
+
+#![warn(clippy::if_let_some_result)]
+
+fn str_to_int(x: &str) -> i32 {
+    if let Some(y) = x.parse().ok() {
+        y
+    } else {
+        0
+    }
+}
+
+fn str_to_int_ok(x: &str) -> i32 {
+    if let Ok(y) = x.parse() {
+        y
+    } else {
+        0
+    }
+}
+
+#[rustfmt::skip]
+fn strange_some_no_else(x: &str) -> i32 {
+    {
+        if let Some(y) = x   .   parse()   .   ok   ()    {
+            return y;
+        };
+        0
+    }
+}
+
+fn main() {
+    let _ = str_to_int("1");
+    let _ = str_to_int_ok("2");
+    let _ = strange_some_no_else("3");
+}

tests/ui/if_let_some_result.stderr

@@ -0,0 +1,25 @@
+error: Matching on `Some` with `ok()` is redundant
+  --> $DIR/if_let_some_result.rs:6:5
+   |
+LL |     if let Some(y) = x.parse().ok() {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::if-let-some-result` implied by `-D warnings`
+help: Consider matching on `Ok(y)` and removing the call to `ok` instead
+   |
+LL |     if let Ok(y) = x.parse() {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: Matching on `Some` with `ok()` is redundant
+  --> $DIR/if_let_some_result.rs:24:9
+   |
+LL |         if let Some(y) = x   .   parse()   .   ok   ()    {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: Consider matching on `Ok(y)` and removing the call to `ok` instead
+   |
+LL |         if let Ok(y) = x   .   parse()       {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+