refactor: move into methods module

2 files changed, 109 insertions, 0 deletions

diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
index aa9f86f292c..1e76428858b 100644
--- a/clippy_lints/src/methods/mod.rs
+++ b/clippy_lints/src/methods/mod.rs
@@ -45,6 +45,7 @@ mod option_as_ref_deref;
 mod option_map_or_none;
 mod option_map_unwrap_or;
 mod or_fun_call;
+mod or_then_unwrap;
 mod search_is_some;
 mod single_char_add_str;
 mod single_char_insert_string;
@@ -780,6 +781,42 @@ declare_clippy_lint! {
 
 declare_clippy_lint! {
     /// ### What it does
+    /// Checks for `.or(…).unwrap()` calls to Options and Results.
+    ///
+    /// ### Why is this bad?
+    /// You should use `.unwrap_or(…)` instead for clarity.
+    ///
+    /// ### Example
+    /// ```rust
+    /// # let fallback = "fallback";
+    /// // Result
+    /// # type Error = &'static str;
+    /// # let result: Result<&str, Error> = Err("error");
+    /// let value = result.or::<Error>(Ok(fallback)).unwrap();
+    ///
+    /// // Option
+    /// # let option: Option<&str> = None;
+    /// let value = option.or(Some(fallback)).unwrap();
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// # let fallback = "fallback";
+    /// // Result
+    /// # let result: Result<&str, &str> = Err("error");
+    /// let value = result.unwrap_or(fallback);
+    ///
+    /// // Option
+    /// # let option: Option<&str> = None;
+    /// let value = option.unwrap_or(fallback);
+    /// ```
+    #[clippy::version = "1.61.0"]
+    pub OR_THEN_UNWRAP,
+    complexity,
+    "checks for `.or(…).unwrap()` calls to Options and Results."
+}
+
+declare_clippy_lint! {
+    /// ### What it does
     /// Checks for calls to `.expect(&format!(...))`, `.expect(foo(..))`,
     /// etc., and suggests to use `unwrap_or_else` instead
     ///
@@ -2039,6 +2076,7 @@ impl_lint_pass!(Methods => [
     OPTION_MAP_OR_NONE,
     BIND_INSTEAD_OF_MAP,
     OR_FUN_CALL,
+    OR_THEN_UNWRAP,
     EXPECT_FUN_CALL,
     CHARS_NEXT_CMP,
     CHARS_LAST_CMP,
@@ -2474,6 +2512,9 @@ fn check_methods<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, msrv: Optio
                     Some(("get_mut", [recv, get_arg], _)) => {
                         get_unwrap::check(cx, expr, recv, get_arg, true);
                     },
+                    Some(("or", [recv, or_arg], or_span)) => {
+                        or_then_unwrap::check(cx, expr, recv, or_arg, or_span);
+                    },
                     _ => {},
                 }
                 unwrap_used::check(cx, expr, recv);
diff --git a/clippy_lints/src/methods/or_then_unwrap.rs b/clippy_lints/src/methods/or_then_unwrap.rs
new file mode 100644
index 00000000000..02fa5887f67
--- /dev/null
+++ b/clippy_lints/src/methods/or_then_unwrap.rs
@@ -0,0 +1,68 @@
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::ty::is_type_diagnostic_item;
+use if_chain::if_chain;
+use rustc_hir::{Expr, ExprKind, QPath};
+use rustc_lint::LateContext;
+use rustc_span::{sym, Span};
+
+use super::OR_THEN_UNWRAP;
+
+pub(super) fn check<'tcx>(
+    cx: &LateContext<'tcx>,
+    unwrap_expr: &Expr<'_>,
+    recv: &'tcx Expr<'tcx>,
+    or_arg: &'tcx Expr<'_>,
+    or_span: Span,
+) {
+    let ty = cx.typeck_results().expr_ty(recv); // get type of x (we later check if it's Option or Result)
+    let title;
+
+    if is_type_diagnostic_item(cx, ty, sym::Option) {
+        title = ".or(Some(…)).unwrap() found";
+        if !is(or_arg, "Some") {
+            return;
+        }
+    } else if is_type_diagnostic_item(cx, ty, sym::Result) {
+        title = ".or(Ok(…)).unwrap() found";
+        if !is(or_arg, "Ok") {
+            return;
+        }
+    } else {
+        // Someone has implemented a struct with .or(...).unwrap() chaining,
+        // but it's not an Option or a Result, so bail
+        return;
+    }
+
+    let unwrap_span = if let ExprKind::MethodCall(_, _, span) = unwrap_expr.kind {
+        span
+    } else {
+        // unreachable. but fallback to ident's span ("()" are missing)
+        unwrap_expr.span
+    };
+
+    span_lint_and_help(
+        cx,
+        OR_THEN_UNWRAP,
+        or_span.to(unwrap_span),
+        title,
+        None,
+        "use `unwrap_or()` instead",
+    );
+}
+
+/// is expr a Call to name?
+/// name might be "Some", "Ok", "Err", etc.
+fn is<'a>(expr: &Expr<'a>, name: &str) -> bool {
+    if_chain! {
+        if let ExprKind::Call(some_expr, _some_args) = expr.kind;
+        if let ExprKind::Path(QPath::Resolved(_, path)) = &some_expr.kind;
+        if let Some(path_segment) = path.segments.first();
+        if path_segment.ident.name.as_str() == name;
+        then {
+            true
+        }
+        else {
+            false
+        }
+    }
+}