Rollup merge of #96677 - jyn514:label-break-value-tests, r=petrochenkov

Add more tests for label-break-value

Helps with #48594. The tests are adapted from #48594 (comment).

src/test/ui/for-loop-while/label_break_value.rs

@@ -95,6 +95,50 @@ fn label_break_mixed(v: u32) -> u32 {
     r
 }
 
+fn label_break_match(c: u8, xe: u8, ye: i8) {
+    let mut x = 0;
+    let y = 'a: {
+        match c {
+            0 => break 'a 0,
+            v if { if v % 2 == 0 { break 'a 1; }; v % 3 == 0 } => { x += 1; },
+            v if { 'b: { break 'b v == 5; } } => { x = 41; },
+            _ => 'b: { //~ WARNING `'b` shadows a label
+                break 'b ();
+            },
+        }
+        x += 1;
+        -1
+    };
+
+    assert_eq!(x, xe);
+    assert_eq!(y, ye);
+}
+
+#[allow(unused_labels)]
+fn label_break_macro() {
+    macro_rules! mac1 {
+        ($target:lifetime, $val:expr) => {
+            break $target $val;
+        };
+    }
+    let x: u8 = 'a: {
+        'b: {
+            mac1!('b, 1);
+        };
+        0
+    };
+    assert_eq!(x, 0);
+    let x: u8 = 'a: { //~ WARNING `'a` shadows a label
+        'b: { //~ WARNING `'b` shadows a label
+            if true {
+                mac1!('a, 1);
+            }
+        };
+        0
+    };
+    assert_eq!(x, 1);
+}
+
 pub fn main() {
     assert_eq!(label_break(true, false), 1);
     assert_eq!(label_break(false, true), 2);
@@ -112,5 +156,12 @@ pub fn main() {
     assert_eq!(label_break_mixed(5), 5);
     assert_eq!(label_break_mixed(6), 6);
 
-    // FIXME: ensure that labeled blocks work if produced by macros and in match arms
+    label_break_match(0, 0, 0);
+    label_break_match(1, 1, -1);
+    label_break_match(2, 0, 1);
+    label_break_match(3, 2, -1);
+    label_break_match(5, 42, -1);
+    label_break_match(7, 1, -1);
+
+    label_break_macro();
 }

src/test/ui/for-loop-while/label_break_value.stderr

@@ -0,0 +1,28 @@
+warning: label name `'b` shadows a label name that is already in scope
+  --> $DIR/label_break_value.rs:105:18
+   |
+LL |             v if { 'b: { break 'b v == 5; } } => { x = 41; },
+   |                    -- first declared here
+LL |             _ => 'b: {
+   |                  ^^ label `'b` already in scope
+
+warning: label name `'a` shadows a label name that is already in scope
+  --> $DIR/label_break_value.rs:131:17
+   |
+LL |     let x: u8 = 'a: {
+   |                 -- first declared here
+...
+LL |     let x: u8 = 'a: {
+   |                 ^^ label `'a` already in scope
+
+warning: label name `'b` shadows a label name that is already in scope
+  --> $DIR/label_break_value.rs:132:9
+   |
+LL |         'b: {
+   |         -- first declared here
+...
+LL |         'b: {
+   |         ^^ label `'b` already in scope
+
+warning: 3 warnings emitted
+

src/test/ui/for-loop-while/label_break_value_invalid.rs

@@ -0,0 +1,39 @@
+#![crate_type = "lib"]
+#![feature(label_break_value)]
+
+fn lbv_macro_test_hygiene_respected() {
+    macro_rules! mac2 {
+        ($val:expr) => {
+            break 'a $val; //~ ERROR undeclared label `'a` [E0426]
+        };
+    }
+    let x: u8 = 'a: {
+        'b: {
+            if true {
+                mac2!(2);
+            }
+        };
+        0
+    };
+    assert_eq!(x, 2);
+
+    macro_rules! mac3 {
+        ($val:expr) => {
+            'a: {
+            //~^ WARNING `'a` shadows a label
+            //~| WARNING `'a` shadows a label
+            //~| WARNING `'a` shadows a label
+                $val
+            }
+        };
+    }
+    let x: u8 = mac3!('b: { //~ WARNING `'b` shadows a label
+        if true {
+            break 'a 3; //~ ERROR undeclared label `'a` [E0426]
+        }
+        0
+    });
+    assert_eq!(x, 3);
+    let x: u8 = mac3!(break 'a 4); //~ ERROR undeclared label `'a` [E0426]
+    assert_eq!(x, 4);
+}

src/test/ui/for-loop-while/label_break_value_invalid.stderr

@@ -0,0 +1,89 @@
+error[E0426]: use of undeclared label `'a`
+  --> $DIR/label_break_value_invalid.rs:7:19
+   |
+LL |             break 'a $val;
+   |                   ^^ undeclared label `'a`
+...
+LL |                 mac2!(2);
+   |                 -------- in this macro invocation
+   |
+   = note: this error originates in the macro `mac2` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0426]: use of undeclared label `'a`
+  --> $DIR/label_break_value_invalid.rs:32:19
+   |
+LL |     let x: u8 = mac3!('b: {
+   |                       -- a label with a similar name is reachable
+LL |         if true {
+LL |             break 'a 3;
+   |                   ^^
+   |                   |
+   |                   undeclared label `'a`
+   |                   help: try using similarly named label: `'b`
+
+error[E0426]: use of undeclared label `'a`
+  --> $DIR/label_break_value_invalid.rs:37:29
+   |
+LL |     let x: u8 = mac3!(break 'a 4);
+   |                             ^^ undeclared label `'a`
+
+warning: label name `'a` shadows a label name that is already in scope
+  --> $DIR/label_break_value_invalid.rs:22:13
+   |
+LL |       let x: u8 = 'a: {
+   |                   -- first declared here
+...
+LL |               'a: {
+   |               ^^ label `'a` already in scope
+...
+LL |       let x: u8 = mac3!('b: {
+   |  _________________-
+LL | |         if true {
+LL | |             break 'a 3;
+LL | |         }
+LL | |         0
+LL | |     });
+   | |______- in this macro invocation
+   |
+   = note: this warning originates in the macro `mac3` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+warning: label name `'b` shadows a label name that is already in scope
+  --> $DIR/label_break_value_invalid.rs:30:23
+   |
+LL |         'b: {
+   |         -- first declared here
+...
+LL |     let x: u8 = mac3!('b: {
+   |                       ^^ label `'b` already in scope
+
+warning: label name `'a` shadows a label name that is already in scope
+  --> $DIR/label_break_value_invalid.rs:22:13
+   |
+LL |     let x: u8 = 'a: {
+   |                 -- first declared here
+...
+LL |             'a: {
+   |             ^^ label `'a` already in scope
+...
+LL |     let x: u8 = mac3!(break 'a 4);
+   |                 ----------------- in this macro invocation
+   |
+   = note: this warning originates in the macro `mac3` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+warning: label name `'a` shadows a label name that is already in scope
+  --> $DIR/label_break_value_invalid.rs:22:13
+   |
+LL |             'a: {
+   |             ^^
+   |             |
+   |             first declared here
+   |             label `'a` already in scope
+...
+LL |     let x: u8 = mac3!(break 'a 4);
+   |                 ----------------- in this macro invocation
+   |
+   = note: this warning originates in the macro `mac3` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 3 previous errors; 4 warnings emitted
+
+For more information about this error, try `rustc --explain E0426`.