added file again

clippy_lints/src/ok_if_let.rs

@@ -0,0 +1,53 @@
+use rustc::lint::*;
+use rustc::hir::*;
+use utils::{paths, method_chain_args, span_help_and_lint, match_type};
+
+/// **What it does:*** Checks for unnecessary `ok()` in if let.
+///
+/// **Why is this bad?** Calling `ok()` in if let is unnecessary, instead match on `Ok(x`
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rustc
+/// for result in iter {
+///     if let Some(bench) = try!(result).parse().ok() {
+///         vec.push(bench)
+///     }
+/// }
+/// ```
+declare_lint! {
+    pub IF_LET_SOME_RESULT,
+    Warn,
+    "usage of `ok()` in `if let Some(x)` statements is unnecessary, match on `Ok(expr)` instead"
+}
+
+#[derive(Copy, Clone)]
+pub struct OkIfLetPass;
+
+impl LintPass for OkIfLetPass {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(IF_LET_SOME_RESULT)
+    }
+}
+
+impl LateLintPass for OkIfLetPass {
+    fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
+        if_let_chain! {[ //begin checking variables
+            let ExprMatch(ref op, ref body, ref source) = expr.node, //test if expr is a match
+            let MatchSource::IfLetDesugar { contains_else_clause: _ } = *source, //test if it is an If Let
+            let ExprMethodCall(_, _, ref result_types) = op.node, //check is expr.ok() has type Result<T,E>.ok()
+            let PatKind::TupleStruct(ref x, ref y, _)  = body[0].pats[0].node, //get operation
+            let Some(_) = method_chain_args(op, &["ok"]) //test to see if using ok() methoduse std::marker::Sized;
+
+        ], {
+            let is_result_type = match_type(cx, cx.tcx.expr_ty(&result_types[0]), &paths::RESULT);
+            let some_expr_string = print::pat_to_string(&y[0]);
+            if print::path_to_string(x) == "Some" && is_result_type {
+                span_help_and_lint(cx, IF_LET_SOME_RESULT, expr.span,
+                "Matching on `Some` with `ok()` is redundant",
+                &format!("Consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string)); 
+            }
+        }}
+    }
+}