Update upstream source from tag 'upstream/1.52.1+dfsg1'

[rustc.git] / src / tools / clippy / tests / ui / unnecessary_fold.rs

diff --git a/src/tools/clippy/tests/ui/unnecessary_fold.rs b/src/tools/clippy/tests/ui/unnecessary_fold.rs
new file mode 100644 (file)
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+++ b/src/tools/clippy/tests/ui/unnecessary_fold.rs
@@ -0,0 +1,52 @@
+// run-rustfix
+
+#![allow(dead_code)]
+
+/// Calls which should trigger the `UNNECESSARY_FOLD` lint
+fn unnecessary_fold() {
+    // Can be replaced by .any
+    let _ = (0..3).fold(false, |acc, x| acc || x > 2);
+    // Can be replaced by .all
+    let _ = (0..3).fold(true, |acc, x| acc && x > 2);
+    // Can be replaced by .sum
+    let _: i32 = (0..3).fold(0, |acc, x| acc + x);
+    // Can be replaced by .product
+    let _: i32 = (0..3).fold(1, |acc, x| acc * x);
+}
+
+/// Should trigger the `UNNECESSARY_FOLD` lint, with an error span including exactly `.fold(...)`
+fn unnecessary_fold_span_for_multi_element_chain() {
+    let _: bool = (0..3).map(|x| 2 * x).fold(false, |acc, x| acc || x > 2);
+}
+
+/// Calls which should not trigger the `UNNECESSARY_FOLD` lint
+fn unnecessary_fold_should_ignore() {
+    let _ = (0..3).fold(true, |acc, x| acc || x > 2);
+    let _ = (0..3).fold(false, |acc, x| acc && x > 2);
+    let _ = (0..3).fold(1, |acc, x| acc + x);
+    let _ = (0..3).fold(0, |acc, x| acc * x);
+    let _ = (0..3).fold(0, |acc, x| 1 + acc + x);
+
+    // We only match against an accumulator on the left
+    // hand side. We could lint for .sum and .product when
+    // it's on the right, but don't for now (and this wouldn't
+    // be valid if we extended the lint to cover arbitrary numeric
+    // types).
+    let _ = (0..3).fold(false, |acc, x| x > 2 || acc);
+    let _ = (0..3).fold(true, |acc, x| x > 2 && acc);
+    let _ = (0..3).fold(0, |acc, x| x + acc);
+    let _ = (0..3).fold(1, |acc, x| x * acc);
+
+    let _ = [(0..2), (0..3)].iter().fold(0, |a, b| a + b.len());
+    let _ = [(0..2), (0..3)].iter().fold(1, |a, b| a * b.len());
+}
+
+/// Should lint only the line containing the fold
+fn unnecessary_fold_over_multiple_lines() {
+    let _ = (0..3)
+        .map(|x| x + 1)
+        .filter(|x| x % 2 == 0)
+        .fold(false, |acc, x| acc || x > 2);
+}
+
+fn main() {}