Avoid infinite loop in function arguments checking

Author: chenyukang

compiler/rustc_typeck/src/check/fn_ctxt/arg_matrix.rs

@@ -364,7 +364,14 @@ impl<'tcx> ArgMatrix<'tcx> {
                 None => {
                     // We didn't find any issues, so we need to push the algorithm forward
                     // First, eliminate any arguments that currently satisfy their inputs
-                    for (inp, arg) in self.eliminate_satisfied() {
+                    let eliminated = self.eliminate_satisfied();
+                    if eliminated.len() == 0 {
+                        // In every iteration, we should reduce the size of provided_indices or expected_indices
+                        // Othewise, means we meet an weird compatibility_matrix which we can not shrink the size,
+                        // we will get into infinite loop if we don't break the loop, see #100478
+                        break;
+                    }
+                    for (inp, arg) in eliminated {
                         matched_inputs[arg] = Some(inp);
                     }
                 }

src/test/ui/argument-suggestions/issue-100478.rs

@@ -0,0 +1,65 @@
+use std::sync::Arc;
+macro_rules! GenT {
+    ($name:tt) => {
+        #[derive(Default, Debug)]
+        struct $name {
+            #[allow(unused)]
+            val: i32,
+        }
+
+        impl $name {
+            #[allow(unused)]
+            fn new(val: i32) -> Self {
+                $name { val }
+            }
+        }
+    };
+}
+
+GenT!(T1);
+GenT!(T2);
+GenT!(T3);
+GenT!(T4);
+GenT!(T5);
+GenT!(T6);
+GenT!(T7);
+GenT!(T8);
+GenT!(T9);
+GenT!(T10);
+GenT!(T11);
+
+#[allow(unused)]
+fn foo(
+    p1: T1,
+    p2: Arc<T2>,
+    p3: T3,
+    p4: Arc<T4>,
+    p5: T5,
+    p6: T6,
+    p7: T7,
+    p8: Arc<T8>,
+    p9: T9,
+    p10: T10,
+    p11: T11,
+) {
+}
+
+fn main() {
+    let p1 = T1::new(0);
+    let p2 = Arc::new(T2::new(0));
+    let p3 = T3::new(0);
+    let p4 = Arc::new(T4::new(1));
+    let p5 = T5::new(0);
+    let p6 = T6::new(0);
+    let p7 = T7::new(0);
+    let p8 = Arc::default();
+    let p9 = T9::new(0);
+    let p10 = T10::new(0);
+    let p11 = T11::new(0);
+
+    foo(
+        //~^ ERROR 60:5: 60:8: this function takes 11 arguments but 10 arguments were supplied [E0061]
+        p1, //p2,
+        p3, p4, p5, p6, p7, p8, p9, p10, p11,
+    );
+}

src/test/ui/argument-suggestions/issue-100478.stderr

@@ -0,0 +1,41 @@
+error[E0061]: this function takes 11 arguments but 10 arguments were supplied
+  --> $DIR/issue-100478.rs:60:5
+   |
+LL |     foo(
+   |     ^^^
+   |
+note: function defined here
+  --> $DIR/issue-100478.rs:32:4
+   |
+LL | fn foo(
+   |    ^^^
+LL |     p1: T1,
+   |     ------
+LL |     p2: Arc<T2>,
+   |     -----------
+LL |     p3: T3,
+   |     ------
+LL |     p4: Arc<T4>,
+   |     -----------
+LL |     p5: T5,
+   |     ------
+LL |     p6: T6,
+   |     ------
+LL |     p7: T7,
+   |     ------
+LL |     p8: Arc<T8>,
+   |     -----------
+LL |     p9: T9,
+   |     ------
+LL |     p10: T10,
+   |     --------
+LL |     p11: T11,
+   |     --------
+help: did you mean
+   |
+LL |     foo(p1, /* Arc<T2> */, /* T3 */, /* Arc<T4> */, /* T5 */, /* T6 */, /* T7 */, /* Arc<T8> */, /* T9 */, /* T10 */, /* T11 */);
+   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0061`.