Only suggest map_or for copy types

clippy_lints/src/methods/mod.rs

@@ -22,6 +22,7 @@ use syntax::ast;
 use syntax::source_map::{BytePos, Span};
 use syntax::symbol::LocalInternedString;
 
+mod option_map_unwrap_or;
 mod unnecessary_filter_map;
 
 #[derive(Clone)]
@@ -836,7 +837,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
             ["unwrap", "get_mut"] => lint_get_unwrap(cx, expr, arg_lists[1], true),
             ["unwrap", ..] => lint_unwrap(cx, expr, arg_lists[0]),
             ["expect", "ok"] => lint_ok_expect(cx, expr, arg_lists[1]),
-            ["unwrap_or", "map"] => lint_map_unwrap_or(cx, expr, arg_lists[1], arg_lists[0]),
+            ["unwrap_or", "map"] => option_map_unwrap_or::lint(cx, expr, arg_lists[1], arg_lists[0]),
             ["unwrap_or_else", "map"] => lint_map_unwrap_or_else(cx, expr, arg_lists[1], arg_lists[0]),
             ["map_or", ..] => lint_map_or_none(cx, expr, arg_lists[0]),
             ["next", "filter"] => lint_filter_next(cx, expr, arg_lists[1]),
@@ -1769,48 +1770,6 @@ fn lint_ok_expect(cx: &LateContext<'_, '_>, expr: &hir::Expr, ok_args: &[hir::Ex
     }
 }
 
-/// lint use of `map().unwrap_or()` for `Option`s
-fn lint_map_unwrap_or(cx: &LateContext<'_, '_>, expr: &hir::Expr, map_args: &[hir::Expr], unwrap_args: &[hir::Expr]) {
-    // lint if the caller of `map()` is an `Option`
-    if match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION) {
-        // get snippets for args to map() and unwrap_or()
-        let map_snippet = snippet(cx, map_args[1].span, "..");
-        let unwrap_snippet = snippet(cx, unwrap_args[1].span, "..");
-        // lint message
-        // comparing the snippet from source to raw text ("None") below is safe
-        // because we already have checked the type.
-        let arg = if unwrap_snippet == "None" { "None" } else { "a" };
-        let suggest = if unwrap_snippet == "None" {
-            "and_then(f)"
-        } else {
-            "map_or(a, f)"
-        };
-        let msg = &format!(
-            "called `map(f).unwrap_or({})` on an Option value. \
-             This can be done more directly by calling `{}` instead",
-            arg, suggest
-        );
-        // lint, with note if neither arg is > 1 line and both map() and
-        // unwrap_or() have the same span
-        let multiline = map_snippet.lines().count() > 1 || unwrap_snippet.lines().count() > 1;
-        let same_span = map_args[1].span.ctxt() == unwrap_args[1].span.ctxt();
-        if same_span && !multiline {
-            let suggest = if unwrap_snippet == "None" {
-                format!("and_then({})", map_snippet)
-            } else {
-                format!("map_or({}, {})", unwrap_snippet, map_snippet)
-            };
-            let note = format!(
-                "replace `map({}).unwrap_or({})` with `{}`",
-                map_snippet, unwrap_snippet, suggest
-            );
-            span_note_and_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg, expr.span, &note);
-        } else if same_span && multiline {
-            span_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg);
-        };
-    }
-}
-
 /// lint use of `map().flatten()` for `Iterators`
 fn lint_map_flatten<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, map_args: &'tcx [hir::Expr]) {
     // lint if caller of `.map().flatten()` is an Iterator

clippy_lints/src/methods/option_map_unwrap_or.rs

@@ -0,0 +1,122 @@
+use crate::utils::paths;
+use crate::utils::{is_copy, match_type, snippet, span_lint, span_note_and_lint};
+use rustc::hir::intravisit::{walk_path, NestedVisitorMap, Visitor};
+use rustc::hir::{self, *};
+use rustc::lint::LateContext;
+use rustc_data_structures::fx::FxHashSet;
+use syntax::symbol::Symbol;
+
+use super::OPTION_MAP_UNWRAP_OR;
+
+/// lint use of `map().unwrap_or()` for `Option`s
+pub(super) fn lint<'a, 'tcx>(
+    cx: &LateContext<'a, 'tcx>,
+    expr: &hir::Expr,
+    map_args: &'tcx [hir::Expr],
+    unwrap_args: &'tcx [hir::Expr],
+) {
+    // lint if the caller of `map()` is an `Option`
+    if match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION) {
+        if !is_copy(cx, cx.tables.expr_ty(&unwrap_args[1])) {
+            // Do not lint if the `map` argument uses identifiers in the `map`
+            // argument that are also used in the `unwrap_or` argument
+
+            let mut unwrap_visitor = UnwrapVisitor {
+                cx,
+                identifiers: FxHashSet::default(),
+            };
+            unwrap_visitor.visit_expr(&unwrap_args[1]);
+
+            let mut map_expr_visitor = MapExprVisitor {
+                cx,
+                identifiers: unwrap_visitor.identifiers,
+                found_identifier: false,
+            };
+            map_expr_visitor.visit_expr(&map_args[1]);
+
+            if map_expr_visitor.found_identifier {
+                return;
+            }
+        }
+
+        // get snippets for args to map() and unwrap_or()
+        let map_snippet = snippet(cx, map_args[1].span, "..");
+        let unwrap_snippet = snippet(cx, unwrap_args[1].span, "..");
+        // lint message
+        // comparing the snippet from source to raw text ("None") below is safe
+        // because we already have checked the type.
+        let arg = if unwrap_snippet == "None" { "None" } else { "a" };
+        let suggest = if unwrap_snippet == "None" {
+            "and_then(f)"
+        } else {
+            "map_or(a, f)"
+        };
+        let msg = &format!(
+            "called `map(f).unwrap_or({})` on an Option value. \
+             This can be done more directly by calling `{}` instead",
+            arg, suggest
+        );
+        // lint, with note if neither arg is > 1 line and both map() and
+        // unwrap_or() have the same span
+        let multiline = map_snippet.lines().count() > 1 || unwrap_snippet.lines().count() > 1;
+        let same_span = map_args[1].span.ctxt() == unwrap_args[1].span.ctxt();
+        if same_span && !multiline {
+            let suggest = if unwrap_snippet == "None" {
+                format!("and_then({})", map_snippet)
+            } else {
+                format!("map_or({}, {})", unwrap_snippet, map_snippet)
+            };
+            let note = format!(
+                "replace `map({}).unwrap_or({})` with `{}`",
+                map_snippet, unwrap_snippet, suggest
+            );
+            span_note_and_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg, expr.span, &note);
+        } else if same_span && multiline {
+            span_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg);
+        };
+    }
+}
+
+struct UnwrapVisitor<'a, 'tcx: 'a> {
+    cx: &'a LateContext<'a, 'tcx>,
+    identifiers: FxHashSet<Symbol>,
+}
+
+impl<'a, 'tcx: 'a> Visitor<'tcx> for UnwrapVisitor<'a, 'tcx> {
+    fn visit_path(&mut self, path: &'tcx Path, _id: HirId) {
+        self.identifiers.insert(ident(path));
+        walk_path(self, path);
+    }
+
+    fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
+        NestedVisitorMap::All(&self.cx.tcx.hir())
+    }
+}
+
+struct MapExprVisitor<'a, 'tcx: 'a> {
+    cx: &'a LateContext<'a, 'tcx>,
+    identifiers: FxHashSet<Symbol>,
+    found_identifier: bool,
+}
+
+impl<'a, 'tcx: 'a> Visitor<'tcx> for MapExprVisitor<'a, 'tcx> {
+    fn visit_path(&mut self, path: &'tcx Path, _id: HirId) {
+        if self.identifiers.contains(&ident(path)) {
+            self.found_identifier = true;
+            return;
+        }
+        walk_path(self, path);
+    }
+
+    fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
+        NestedVisitorMap::All(&self.cx.tcx.hir())
+    }
+}
+
+fn ident(path: &Path) -> Symbol {
+    path.segments
+        .last()
+        .expect("segments should be composed of at least 1 element")
+        .ident
+        .name
+}

tests/ui/methods.rs

@@ -179,6 +179,13 @@ fn option_methods() {
     // macro case
     let _ = opt_map!(opt, |x| x + 1).unwrap_or(0); // should not lint
 
+    // Should not lint if not copyable
+    let id: String = "identifier".to_string();
+    let _ = Some("prefix").map(|p| format!("{}.{}", p, id)).unwrap_or(id);
+    // ...but DO lint if the `unwrap_or` argument is not used in the `map`
+    let id: String = "identifier".to_string();
+    let _ = Some("prefix").map(|p| format!("{}.", p)).unwrap_or(id);
+
     // Check OPTION_MAP_UNWRAP_OR_ELSE
     // single line case
     let _ = opt.map(|x| x + 1)