Auto merge of #141652 - compiler-errors:more-collect-and-apply, r=<try>

[PERF] More collect and apply

I saw that we have quite a few `collect_and_apply` calls for N=3-7 (N=7 corresponding to cumulative 99% of nalgebra's calls). Didn't perf locally, but also this is super low-pri, so let's see what rust-timer says.

Author: bors

compiler/rustc_type_ir/src/interner.rs

@@ -402,6 +402,51 @@ impl<T, R> CollectAndApply<T, R> for T {
                 assert!(iter.next().is_none());
                 f(&[t0, t1])
             }
+            (3, Some(3)) => {
+                let t0 = iter.next().unwrap();
+                let t1 = iter.next().unwrap();
+                let t2 = iter.next().unwrap();
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2])
+            }
+            (4, Some(4)) => {
+                let t0 = iter.next().unwrap();
+                let t1 = iter.next().unwrap();
+                let t2 = iter.next().unwrap();
+                let t3 = iter.next().unwrap();
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2, t3])
+            }
+            (5, Some(5)) => {
+                let t0 = iter.next().unwrap();
+                let t1 = iter.next().unwrap();
+                let t2 = iter.next().unwrap();
+                let t3 = iter.next().unwrap();
+                let t4 = iter.next().unwrap();
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2, t3, t4])
+            }
+            (6, Some(6)) => {
+                let t0 = iter.next().unwrap();
+                let t1 = iter.next().unwrap();
+                let t2 = iter.next().unwrap();
+                let t3 = iter.next().unwrap();
+                let t4 = iter.next().unwrap();
+                let t5 = iter.next().unwrap();
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2, t3, t4, t5])
+            }
+            (7, Some(7)) => {
+                let t0 = iter.next().unwrap();
+                let t1 = iter.next().unwrap();
+                let t2 = iter.next().unwrap();
+                let t3 = iter.next().unwrap();
+                let t4 = iter.next().unwrap();
+                let t5 = iter.next().unwrap();
+                let t6 = iter.next().unwrap();
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2, t3, t4, t5, t6])
+            }
             _ => f(&iter.collect::<SmallVec<[_; 8]>>()),
         }
     }
@@ -440,6 +485,51 @@ impl<T, R, E> CollectAndApply<T, R> for Result<T, E> {
                 assert!(iter.next().is_none());
                 f(&[t0, t1])
             }
+            (3, Some(3)) => {
+                let t0 = iter.next().unwrap()?;
+                let t1 = iter.next().unwrap()?;
+                let t2 = iter.next().unwrap()?;
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2])
+            }
+            (4, Some(4)) => {
+                let t0 = iter.next().unwrap()?;
+                let t1 = iter.next().unwrap()?;
+                let t2 = iter.next().unwrap()?;
+                let t3 = iter.next().unwrap()?;
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2, t3])
+            }
+            (5, Some(5)) => {
+                let t0 = iter.next().unwrap()?;
+                let t1 = iter.next().unwrap()?;
+                let t2 = iter.next().unwrap()?;
+                let t3 = iter.next().unwrap()?;
+                let t4 = iter.next().unwrap()?;
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2, t3, t4])
+            }
+            (6, Some(6)) => {
+                let t0 = iter.next().unwrap()?;
+                let t1 = iter.next().unwrap()?;
+                let t2 = iter.next().unwrap()?;
+                let t3 = iter.next().unwrap()?;
+                let t4 = iter.next().unwrap()?;
+                let t5 = iter.next().unwrap()?;
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2, t3, t4, t5])
+            }
+            (7, Some(7)) => {
+                let t0 = iter.next().unwrap()?;
+                let t1 = iter.next().unwrap()?;
+                let t2 = iter.next().unwrap()?;
+                let t3 = iter.next().unwrap()?;
+                let t4 = iter.next().unwrap()?;
+                let t5 = iter.next().unwrap()?;
+                let t6 = iter.next().unwrap()?;
+                assert!(iter.next().is_none());
+                f(&[t0, t1, t2, t3, t4, t5, t6])
+            }
             _ => f(&iter.collect::<Result<SmallVec<[_; 8]>, _>>()?),
         })
     }