Move multiple UI issue tests to subdirectories

Issue tests numbered 1920, 3668, 5997, 23302, 32122, 40510, 57741, 71676, and 76077 were moved to relevant better-named subdirectories. ISSUES_ENTRY_LIMIT was adjusted to match new number of files and FIXME note was expanded.

tests/ui/issues/issue-23302-enum-infinite-recursion/issue-23302-1.rs

@@ -0,0 +1,7 @@
+// Check that an enum with recursion in the discriminant throws
+// the appropriate error (rather than, say, blowing the stack).
+enum X {
+    A = X::A as isize, //~ ERROR E0391
+}
+
+fn main() { }

tests/ui/issues/issue-23302-enum-infinite-recursion/issue-23302-1.stderr

@@ -0,0 +1,26 @@
+error[E0391]: cycle detected when simplifying constant for the type system `X::A::{constant#0}`
+  --> $DIR/issue-23302-1.rs:4:9
+   |
+LL |     A = X::A as isize,
+   |         ^^^^^^^^^^^^^
+   |
+note: ...which requires const-evaluating + checking `X::A::{constant#0}`...
+  --> $DIR/issue-23302-1.rs:4:9
+   |
+LL |     A = X::A as isize,
+   |         ^^^^^^^^^^^^^
+   = note: ...which again requires simplifying constant for the type system `X::A::{constant#0}`, completing the cycle
+note: cycle used when collecting item types in top-level module
+  --> $DIR/issue-23302-1.rs:3:1
+   |
+LL | / enum X {
+LL | |     A = X::A as isize,
+LL | | }
+LL | |
+LL | | fn main() { }
+   | |_____________^
+   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0391`.

tests/ui/issues/issue-23302-enum-infinite-recursion/issue-23302-2.rs

@@ -0,0 +1,8 @@
+// Since `Y::B` here defaults to `Y::A+1`, this is also a
+// recursive definition.
+enum Y {
+    A = Y::B as isize, //~ ERROR E0391
+    B,
+}
+
+fn main() { }

tests/ui/issues/issue-23302-enum-infinite-recursion/issue-23302-2.stderr

@@ -0,0 +1,27 @@
+error[E0391]: cycle detected when simplifying constant for the type system `Y::A::{constant#0}`
+  --> $DIR/issue-23302-2.rs:4:9
+   |
+LL |     A = Y::B as isize,
+   |         ^^^^^^^^^^^^^
+   |
+note: ...which requires const-evaluating + checking `Y::A::{constant#0}`...
+  --> $DIR/issue-23302-2.rs:4:9
+   |
+LL |     A = Y::B as isize,
+   |         ^^^^^^^^^^^^^
+   = note: ...which again requires simplifying constant for the type system `Y::A::{constant#0}`, completing the cycle
+note: cycle used when collecting item types in top-level module
+  --> $DIR/issue-23302-2.rs:3:1
+   |
+LL | / enum Y {
+LL | |     A = Y::B as isize,
+LL | |     B,
+LL | | }
+LL | |
+LL | | fn main() { }
+   | |_____________^
+   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0391`.

tests/ui/issues/issue-23302-enum-infinite-recursion/issue-23302-3.rs

@@ -0,0 +1,5 @@
+const A: i32 = B; //~ ERROR cycle detected
+
+const B: i32 = A;
+
+fn main() { }

tests/ui/issues/issue-23302-enum-infinite-recursion/issue-23302-3.stderr

@@ -0,0 +1,36 @@
+error[E0391]: cycle detected when simplifying constant for the type system `A`
+  --> $DIR/issue-23302-3.rs:1:1
+   |
+LL | const A: i32 = B;
+   | ^^^^^^^^^^^^
+   |
+note: ...which requires const-evaluating + checking `A`...
+  --> $DIR/issue-23302-3.rs:1:16
+   |
+LL | const A: i32 = B;
+   |                ^
+note: ...which requires simplifying constant for the type system `B`...
+  --> $DIR/issue-23302-3.rs:3:1
+   |
+LL | const B: i32 = A;
+   | ^^^^^^^^^^^^
+note: ...which requires const-evaluating + checking `B`...
+  --> $DIR/issue-23302-3.rs:3:16
+   |
+LL | const B: i32 = A;
+   |                ^
+   = note: ...which again requires simplifying constant for the type system `A`, completing the cycle
+note: cycle used when linting top-level module
+  --> $DIR/issue-23302-3.rs:1:1
+   |
+LL | / const A: i32 = B;
+LL | |
+LL | | const B: i32 = A;
+LL | |
+LL | | fn main() { }
+   | |_____________^
+   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0391`.