Extend `unused_must_use` to cover block exprs

3 files changed, 123 insertions, 0 deletions

diff --git a/tests/ui/lint/unused/must-use-block-expr.fixed b/tests/ui/lint/unused/must-use-block-expr.fixed
new file mode 100644
index 00000000000..642012812bd
--- /dev/null
+++ b/tests/ui/lint/unused/must-use-block-expr.fixed
@@ -0,0 +1,36 @@
+// run-rustfix
+// check-pass
+
+#![warn(unused_must_use)]
+
+#[must_use]
+fn foo() -> i32 {
+    42
+}
+
+fn bar() {
+    {
+        let _ = foo();
+        //~^ WARN unused return value
+    }
+}
+
+fn baz() {
+    {
+        let _ = foo();
+        //~^ WARN unused return value
+    };
+}
+
+fn main() {
+    bar();
+    baz();
+    {
+        let _ = 1 + 2;
+        //~^ WARN unused arithmetic operation
+    }
+    {
+        let _ = 1 + 2;
+        //~^ WARN unused arithmetic operation
+    };
+}
diff --git a/tests/ui/lint/unused/must-use-block-expr.rs b/tests/ui/lint/unused/must-use-block-expr.rs
new file mode 100644
index 00000000000..e0a680aa07d
--- /dev/null
+++ b/tests/ui/lint/unused/must-use-block-expr.rs
@@ -0,0 +1,36 @@
+// run-rustfix
+// check-pass
+
+#![warn(unused_must_use)]
+
+#[must_use]
+fn foo() -> i32 {
+    42
+}
+
+fn bar() {
+    {
+        foo();
+        //~^ WARN unused return value
+    }
+}
+
+fn baz() {
+    {
+        foo()
+        //~^ WARN unused return value
+    };
+}
+
+fn main() {
+    bar();
+    baz();
+    {
+        1 + 2;
+        //~^ WARN unused arithmetic operation
+    }
+    {
+        1 + 2
+        //~^ WARN unused arithmetic operation
+    };
+}
diff --git a/tests/ui/lint/unused/must-use-block-expr.stderr b/tests/ui/lint/unused/must-use-block-expr.stderr
new file mode 100644
index 00000000000..d821beb1d92
--- /dev/null
+++ b/tests/ui/lint/unused/must-use-block-expr.stderr
@@ -0,0 +1,51 @@
+warning: unused return value of `foo` that must be used
+  --> $DIR/must-use-block-expr.rs:13:9
+   |
+LL |         foo();
+   |         ^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/must-use-block-expr.rs:4:9
+   |
+LL | #![warn(unused_must_use)]
+   |         ^^^^^^^^^^^^^^^
+help: use `let _ = ...` to ignore the resulting value
+   |
+LL |         let _ = foo();
+   |         +++++++
+
+warning: unused return value of `foo` that must be used
+  --> $DIR/must-use-block-expr.rs:20:9
+   |
+LL |         foo()
+   |         ^^^^^
+   |
+help: use `let _ = ...` to ignore the resulting value
+   |
+LL |         let _ = foo();
+   |         +++++++      +
+
+warning: unused arithmetic operation that must be used
+  --> $DIR/must-use-block-expr.rs:29:9
+   |
+LL |         1 + 2;
+   |         ^^^^^ the arithmetic operation produces a value
+   |
+help: use `let _ = ...` to ignore the resulting value
+   |
+LL |         let _ = 1 + 2;
+   |         +++++++
+
+warning: unused arithmetic operation that must be used
+  --> $DIR/must-use-block-expr.rs:33:9
+   |
+LL |         1 + 2
+   |         ^^^^^ the arithmetic operation produces a value
+   |
+help: use `let _ = ...` to ignore the resulting value
+   |
+LL |         let _ = 1 + 2;
+   |         +++++++      +
+
+warning: 4 warnings emitted
+