Merge pull request rust-lang#2133 from sinkuu/fix_panic

Fix panic with fake `Range` type

Author: llogiq

clippy_lints/src/utils/higher.rs

@@ -50,8 +50,7 @@ pub fn range(expr: &hir::Expr) -> Option<Range> {
     fn get_field<'a>(name: &str, fields: &'a [hir::Field]) -> Option<&'a hir::Expr> {
         let expr = &fields
             .iter()
-            .find(|field| field.name.node == name)
-            .unwrap_or_else(|| panic!("missing {} field for range", name))
+            .find(|field| field.name.node == name)?
             .expr;
 
         Some(expr)
@@ -77,32 +76,32 @@ pub fn range(expr: &hir::Expr) -> Option<Range> {
             match_qpath(path, &paths::RANGE_FROM)
         {
             Some(Range {
-                start: get_field("start", fields),
+                start: Some(get_field("start", fields)?),
                 end: None,
                 limits: ast::RangeLimits::HalfOpen,
             })
         } else if match_qpath(path, &paths::RANGE_INCLUSIVE_STD) || match_qpath(path, &paths::RANGE_INCLUSIVE) {
             Some(Range {
-                start: get_field("start", fields),
-                end: get_field("end", fields),
+                start: Some(get_field("start", fields)?),
+                end: Some(get_field("end", fields)?),
                 limits: ast::RangeLimits::Closed,
             })
         } else if match_qpath(path, &paths::RANGE_STD) || match_qpath(path, &paths::RANGE) {
             Some(Range {
-                start: get_field("start", fields),
-                end: get_field("end", fields),
+                start: Some(get_field("start", fields)?),
+                end: Some(get_field("end", fields)?),
                 limits: ast::RangeLimits::HalfOpen,
             })
         } else if match_qpath(path, &paths::RANGE_TO_INCLUSIVE_STD) || match_qpath(path, &paths::RANGE_TO_INCLUSIVE) {
             Some(Range {
                 start: None,
-                end: get_field("end", fields),
+                end: Some(get_field("end", fields)?),
                 limits: ast::RangeLimits::Closed,
             })
         } else if match_qpath(path, &paths::RANGE_TO_STD) || match_qpath(path, &paths::RANGE_TO) {
             Some(Range {
                 start: None,
-                end: get_field("end", fields),
+                end: Some(get_field("end", fields)?),
                 limits: ast::RangeLimits::HalfOpen,
             })
         } else {

tests/ui/range.rs

@@ -32,3 +32,12 @@ fn main() {
     // check const eval
     let _ = v1.iter().step_by(2/3);
 }
+
+#[allow(unused)]
+fn no_panic_with_fake_range_types() {
+    struct Range {
+        foo: i32,
+    }
+
+    let _ = Range { foo: 0 };
+}