From 873fd50c8657fe000a3df72f07ac6031532b4fd0 Mon Sep 17 00:00:00 2001
From: Odin Dutton <odindutton@gmail.com>
Date: Tue, 23 Apr 2019 15:44:27 +1000
Subject: [PATCH 1/2] Add extended information for E0594

---
 src/librustc_mir/error_codes.rs | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/src/librustc_mir/error_codes.rs b/src/librustc_mir/error_codes.rs
index 74a4278d5991b..9f48bd177f649 100644
--- a/src/librustc_mir/error_codes.rs
+++ b/src/librustc_mir/error_codes.rs
@@ -2062,6 +2062,36 @@ fn get_owned_iterator() -> IntoIter<i32> {
 ```
 "##,
 
+E0594: r##"
+Cannot assign to immutable static item.
+
+Example of erroneous code:
+
+```compile_fail,E0594
+static NUM: i32 = 18;
+NUM = 20; // error: cannot assign
+```
+
+Statics are shared everywhere, and if they are mutable one might violate memory
+safety since holding multiple mutable references to shared data is not allowed.
+
+If you really want global mutable state, try using `static mut`. You will also
+need to wrap the assignment in an `unsafe` block, see E0133.
+
+```
+static mut NUM: i32 = 18;
+unsafe {
+    NUM = 20;
+}
+```
+
+See also:
+
+    https://doc.rust-lang.org/book/ch19-01-unsafe-rust.html
+    https://doc.rust-lang.org/stable/reference/items/static-items.html
+    https://doc.rust-lang.org/stable/rust-by-example/custom_types/constants.html
+"##,
+
 E0595: r##"
 #### Note: this error code is no longer emitted by the compiler.
 
@@ -2435,7 +2465,6 @@ register_diagnostics! {
     E0521,  // borrowed data escapes outside of closure
     E0524, // two closures require unique access to `..` at the same time
     E0526, // shuffle indices are not constant
-    E0594, // cannot assign to {}
     E0598, // lifetime of {} is too short to guarantee its contents can be...
     E0625, // thread-local statics cannot be accessed at compile-time
 }

From 4c86fcb412fec7f7268ccc30b3d48c4e98e67710 Mon Sep 17 00:00:00 2001
From: Odin Dutton <odindutton@gmail.com>
Date: Tue, 23 Apr 2019 21:57:56 +1000
Subject: [PATCH 2/2] Update UI tests with E0594 extended information

---
 src/test/ui/E0594.stderr                                       | 1 +
 src/test/ui/borrowck/borrow-immutable-upvar-mutation.stderr    | 3 ++-
 .../borrowck/borrowck-assign-to-andmut-in-aliasable-loc.stderr | 1 +
 src/test/ui/borrowck/borrowck-assign-to-constants.stderr       | 1 +
 .../borrowck-borrow-mut-base-ptr-in-aliasable-loc.stderr       | 2 +-
 .../ui/borrowck/borrowck-borrow-overloaded-auto-deref.stderr   | 3 ++-
 src/test/ui/borrowck/borrowck-borrow-overloaded-deref.stderr   | 3 ++-
 src/test/ui/borrowck/borrowck-closures-unique.stderr           | 3 ++-
 src/test/ui/borrowck/borrowck-issue-14498.stderr               | 3 ++-
 .../ui/borrowck/borrowck-overloaded-index-ref-index.stderr     | 3 ++-
 src/test/ui/borrowck/index-mut-help.stderr                     | 3 ++-
 src/test/ui/borrowck/issue-45983.nll.stderr                    | 1 +
 .../ui/borrowck/issue-54499-field-mutation-of-moved-out.stderr | 3 ++-
 .../issue-55492-borrowck-migrate-scans-parents.migrate.stderr  | 3 ++-
 .../issue-55492-borrowck-migrate-scans-parents.nll.stderr      | 3 ++-
 src/test/ui/borrowck/mutability-errors.stderr                  | 3 ++-
 .../borrowck/reassignment_immutable_fields_overlapping.stderr  | 3 ++-
 .../ui/borrowck/reassignment_immutable_fields_twice.stderr     | 3 ++-
 src/test/ui/cannot-mutate-captured-non-mut-var.stderr          | 3 ++-
 src/test/ui/closures/closure-immutable-outer-variable.stderr   | 1 +
 src/test/ui/did_you_mean/issue-35937.stderr                    | 3 ++-
 src/test/ui/did_you_mean/issue-39544.stderr                    | 3 ++-
 src/test/ui/error-codes/E0389.stderr                           | 1 +
 src/test/ui/fn/fn-closure-mutable-capture.stderr               | 1 +
 src/test/ui/immut-function-arguments.stderr                    | 1 +
 src/test/ui/issues/issue-46023.stderr                          | 1 +
 src/test/ui/issues/issue-46604.stderr                          | 3 ++-
 src/test/ui/issues/issue-51244.stderr                          | 1 +
 src/test/ui/issues/issue-51515.stderr                          | 1 +
 src/test/ui/mut/mutable-class-fields-2.stderr                  | 1 +
 src/test/ui/mut/mutable-class-fields.stderr                    | 1 +
 src/test/ui/nll/closure-captures.stderr                        | 3 ++-
 src/test/ui/nll/constant-thread-locals-issue-47053.stderr      | 1 +
 src/test/ui/nll/generator-upvar-mutability.stderr              | 1 +
 src/test/ui/nll/issue-47388.stderr                             | 1 +
 src/test/ui/nll/issue-51244.stderr                             | 1 +
 src/test/ui/nll/issue-57989.stderr                             | 3 ++-
 src/test/ui/rfc-2005-default-binding-mode/enum.stderr          | 1 +
 src/test/ui/rfc-2005-default-binding-mode/explicit-mut.stderr  | 1 +
 src/test/ui/suggestions/suggest-ref-mut.stderr                 | 1 +
 src/test/ui/thread-local-mutation.stderr                       | 1 +
 .../unboxed-closures/unboxed-closure-immutable-capture.stderr  | 3 ++-
 .../ui/unboxed-closures/unboxed-closures-mutate-upvar.stderr   | 1 +
 .../unboxed-closures-mutated-upvar-from-fn-closure.stderr      | 1 +
 44 files changed, 64 insertions(+), 21 deletions(-)

diff --git a/src/test/ui/E0594.stderr b/src/test/ui/E0594.stderr
index c00ec4250a70b..f4d96f4e45a56 100644
--- a/src/test/ui/E0594.stderr
+++ b/src/test/ui/E0594.stderr
@@ -6,3 +6,4 @@ LL |     NUM = 20;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/borrow-immutable-upvar-mutation.stderr b/src/test/ui/borrowck/borrow-immutable-upvar-mutation.stderr
index 17969137a9881..097e4c75065c9 100644
--- a/src/test/ui/borrowck/borrow-immutable-upvar-mutation.stderr
+++ b/src/test/ui/borrowck/borrow-immutable-upvar-mutation.stderr
@@ -72,4 +72,5 @@ LL |         let _h = to_fn_mut(move || { set(&mut z); to_fn(move || z = 42); })
 
 error: aborting due to 6 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/borrowck-assign-to-andmut-in-aliasable-loc.stderr b/src/test/ui/borrowck/borrowck-assign-to-andmut-in-aliasable-loc.stderr
index 38fcfbfc2a026..d8ccf36852a51 100644
--- a/src/test/ui/borrowck/borrowck-assign-to-andmut-in-aliasable-loc.stderr
+++ b/src/test/ui/borrowck/borrowck-assign-to-andmut-in-aliasable-loc.stderr
@@ -16,3 +16,4 @@ LL |     *s.pointer += 1;
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/borrowck-assign-to-constants.stderr b/src/test/ui/borrowck/borrowck-assign-to-constants.stderr
index 800003caa0f34..864d933da127f 100644
--- a/src/test/ui/borrowck/borrowck-assign-to-constants.stderr
+++ b/src/test/ui/borrowck/borrowck-assign-to-constants.stderr
@@ -6,3 +6,4 @@ LL |     foo = 6;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/borrowck-borrow-mut-base-ptr-in-aliasable-loc.stderr b/src/test/ui/borrowck/borrowck-borrow-mut-base-ptr-in-aliasable-loc.stderr
index 8115e3150fbce..1fdeb812bf8bb 100644
--- a/src/test/ui/borrowck/borrowck-borrow-mut-base-ptr-in-aliasable-loc.stderr
+++ b/src/test/ui/borrowck/borrowck-borrow-mut-base-ptr-in-aliasable-loc.stderr
@@ -27,5 +27,5 @@ LL |     let x:  &mut isize = &mut **t0;
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0502, E0596.
+Some errors have detailed explanations: E0502, E0594, E0596.
 For more information about an error, try `rustc --explain E0502`.
diff --git a/src/test/ui/borrowck/borrowck-borrow-overloaded-auto-deref.stderr b/src/test/ui/borrowck/borrowck-borrow-overloaded-auto-deref.stderr
index dc52685363e39..2ba162c05e475 100644
--- a/src/test/ui/borrowck/borrowck-borrow-overloaded-auto-deref.stderr
+++ b/src/test/ui/borrowck/borrowck-borrow-overloaded-auto-deref.stderr
@@ -84,4 +84,5 @@ LL |     *x.y_mut() = 3;
 
 error: aborting due to 14 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/borrowck-borrow-overloaded-deref.stderr b/src/test/ui/borrowck/borrowck-borrow-overloaded-deref.stderr
index 1755b22f59dc2..e9471066e4bdc 100644
--- a/src/test/ui/borrowck/borrowck-borrow-overloaded-deref.stderr
+++ b/src/test/ui/borrowck/borrowck-borrow-overloaded-deref.stderr
@@ -42,4 +42,5 @@ LL |     **x = 3;
 
 error: aborting due to 7 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/borrowck-closures-unique.stderr b/src/test/ui/borrowck/borrowck-closures-unique.stderr
index 9b53af4c01f59..546e87b189728 100644
--- a/src/test/ui/borrowck/borrowck-closures-unique.stderr
+++ b/src/test/ui/borrowck/borrowck-closures-unique.stderr
@@ -50,4 +50,5 @@ LL |     let c1 = |y: &'static mut isize| x = y;
 
 error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0500`.
+Some errors have detailed explanations: E0500, E0594.
+For more information about an error, try `rustc --explain E0500`.
diff --git a/src/test/ui/borrowck/borrowck-issue-14498.stderr b/src/test/ui/borrowck/borrowck-issue-14498.stderr
index fec4c27520cf3..ae9167757a0ae 100644
--- a/src/test/ui/borrowck/borrowck-issue-14498.stderr
+++ b/src/test/ui/borrowck/borrowck-issue-14498.stderr
@@ -96,4 +96,5 @@ LL |     drop(p);
 
 error: aborting due to 9 previous errors
 
-For more information about this error, try `rustc --explain E0506`.
+Some errors have detailed explanations: E0506, E0594.
+For more information about an error, try `rustc --explain E0506`.
diff --git a/src/test/ui/borrowck/borrowck-overloaded-index-ref-index.stderr b/src/test/ui/borrowck/borrowck-overloaded-index-ref-index.stderr
index fcbfe72a34b96..def535a62f3c9 100644
--- a/src/test/ui/borrowck/borrowck-overloaded-index-ref-index.stderr
+++ b/src/test/ui/borrowck/borrowck-overloaded-index-ref-index.stderr
@@ -29,4 +29,5 @@ LL |     s[2] = 20;
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0502`.
+Some errors have detailed explanations: E0502, E0594.
+For more information about an error, try `rustc --explain E0502`.
diff --git a/src/test/ui/borrowck/index-mut-help.stderr b/src/test/ui/borrowck/index-mut-help.stderr
index fbc427a6e6d09..96d59b6cecb28 100644
--- a/src/test/ui/borrowck/index-mut-help.stderr
+++ b/src/test/ui/borrowck/index-mut-help.stderr
@@ -22,4 +22,5 @@ LL |     let _ = &mut map["peter"];
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/issue-45983.nll.stderr b/src/test/ui/borrowck/issue-45983.nll.stderr
index 94360b65ffe36..53bf9c1db481c 100644
--- a/src/test/ui/borrowck/issue-45983.nll.stderr
+++ b/src/test/ui/borrowck/issue-45983.nll.stderr
@@ -18,3 +18,4 @@ LL |     give_any(|y| x = Some(y));
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/issue-54499-field-mutation-of-moved-out.stderr b/src/test/ui/borrowck/issue-54499-field-mutation-of-moved-out.stderr
index 7dfd71c81c30d..b7623a54056d8 100644
--- a/src/test/ui/borrowck/issue-54499-field-mutation-of-moved-out.stderr
+++ b/src/test/ui/borrowck/issue-54499-field-mutation-of-moved-out.stderr
@@ -84,4 +84,5 @@ LL |         v.y = 2;
 
 error: aborting due to 9 previous errors
 
-For more information about this error, try `rustc --explain E0382`.
+Some errors have detailed explanations: E0382, E0594.
+For more information about an error, try `rustc --explain E0382`.
diff --git a/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.migrate.stderr b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.migrate.stderr
index f1d28eed922af..1cdcc18632c62 100644
--- a/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.migrate.stderr
+++ b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.migrate.stderr
@@ -50,4 +50,5 @@ LL |         || { &mut x.0; };
 
 error: aborting due to 6 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.nll.stderr b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.nll.stderr
index f1d28eed922af..1cdcc18632c62 100644
--- a/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.nll.stderr
+++ b/src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.nll.stderr
@@ -50,4 +50,5 @@ LL |         || { &mut x.0; };
 
 error: aborting due to 6 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/mutability-errors.stderr b/src/test/ui/borrowck/mutability-errors.stderr
index 545de5d0e75bf..72547a40352c9 100644
--- a/src/test/ui/borrowck/mutability-errors.stderr
+++ b/src/test/ui/borrowck/mutability-errors.stderr
@@ -375,4 +375,5 @@ LL |     &mut X.0;
 
 error: aborting due to 38 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/borrowck/reassignment_immutable_fields_overlapping.stderr b/src/test/ui/borrowck/reassignment_immutable_fields_overlapping.stderr
index 649c127dcc9d4..907681d28edbb 100644
--- a/src/test/ui/borrowck/reassignment_immutable_fields_overlapping.stderr
+++ b/src/test/ui/borrowck/reassignment_immutable_fields_overlapping.stderr
@@ -15,4 +15,5 @@ LL |     x.b = 22;
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0381`.
+Some errors have detailed explanations: E0381, E0594.
+For more information about an error, try `rustc --explain E0381`.
diff --git a/src/test/ui/borrowck/reassignment_immutable_fields_twice.stderr b/src/test/ui/borrowck/reassignment_immutable_fields_twice.stderr
index 9a2824ccb3cd2..bcb6e19c406e5 100644
--- a/src/test/ui/borrowck/reassignment_immutable_fields_twice.stderr
+++ b/src/test/ui/borrowck/reassignment_immutable_fields_twice.stderr
@@ -15,4 +15,5 @@ LL |     x.0 = 1;
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0381`.
+Some errors have detailed explanations: E0381, E0594.
+For more information about an error, try `rustc --explain E0381`.
diff --git a/src/test/ui/cannot-mutate-captured-non-mut-var.stderr b/src/test/ui/cannot-mutate-captured-non-mut-var.stderr
index 2961497ef9f5c..2d6e83c9e82f9 100644
--- a/src/test/ui/cannot-mutate-captured-non-mut-var.stderr
+++ b/src/test/ui/cannot-mutate-captured-non-mut-var.stderr
@@ -16,4 +16,5 @@ LL |     to_fn_once(move|| { s.read_to_end(&mut Vec::new()); });
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/closures/closure-immutable-outer-variable.stderr b/src/test/ui/closures/closure-immutable-outer-variable.stderr
index 558c9caeff336..7e60f3cd8ffa4 100644
--- a/src/test/ui/closures/closure-immutable-outer-variable.stderr
+++ b/src/test/ui/closures/closure-immutable-outer-variable.stderr
@@ -8,3 +8,4 @@ LL |     foo(Box::new(move || y = false) as Box<_>);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/did_you_mean/issue-35937.stderr b/src/test/ui/did_you_mean/issue-35937.stderr
index 4f9b6a6134dc8..1f578d18a1ce5 100644
--- a/src/test/ui/did_you_mean/issue-35937.stderr
+++ b/src/test/ui/did_you_mean/issue-35937.stderr
@@ -24,4 +24,5 @@ LL |     s.x += 1;
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/did_you_mean/issue-39544.stderr b/src/test/ui/did_you_mean/issue-39544.stderr
index dfaaf6b17dc31..ce0d697238c6b 100644
--- a/src/test/ui/did_you_mean/issue-39544.stderr
+++ b/src/test/ui/did_you_mean/issue-39544.stderr
@@ -98,4 +98,5 @@ LL |     *x.0 = 1;
 
 error: aborting due to 12 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/error-codes/E0389.stderr b/src/test/ui/error-codes/E0389.stderr
index 5310367d51a55..c47750b6f4e69 100644
--- a/src/test/ui/error-codes/E0389.stderr
+++ b/src/test/ui/error-codes/E0389.stderr
@@ -8,3 +8,4 @@ LL |     fancy_ref.num = 6;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/fn/fn-closure-mutable-capture.stderr b/src/test/ui/fn/fn-closure-mutable-capture.stderr
index 8dfae0cbdf294..f7ab56da8de97 100644
--- a/src/test/ui/fn/fn-closure-mutable-capture.stderr
+++ b/src/test/ui/fn/fn-closure-mutable-capture.stderr
@@ -12,3 +12,4 @@ LL |     bar(move || x = 1);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/immut-function-arguments.stderr b/src/test/ui/immut-function-arguments.stderr
index 7871ba52db9c9..7238dd14433ce 100644
--- a/src/test/ui/immut-function-arguments.stderr
+++ b/src/test/ui/immut-function-arguments.stderr
@@ -16,3 +16,4 @@ LL |     let _frob = |q: Box<isize>| { *q = 2; };
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/issues/issue-46023.stderr b/src/test/ui/issues/issue-46023.stderr
index fac696c6fdcbf..ca19c2501205d 100644
--- a/src/test/ui/issues/issue-46023.stderr
+++ b/src/test/ui/issues/issue-46023.stderr
@@ -9,3 +9,4 @@ LL |         x = 1;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/issues/issue-46604.stderr b/src/test/ui/issues/issue-46604.stderr
index 961b249daeb0c..c72f580f24391 100644
--- a/src/test/ui/issues/issue-46604.stderr
+++ b/src/test/ui/issues/issue-46604.stderr
@@ -12,4 +12,5 @@ LL |     buf[0]=2;
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0017`.
+Some errors have detailed explanations: E0017, E0594.
+For more information about an error, try `rustc --explain E0017`.
diff --git a/src/test/ui/issues/issue-51244.stderr b/src/test/ui/issues/issue-51244.stderr
index 8a7e71e0326a0..c91083955b820 100644
--- a/src/test/ui/issues/issue-51244.stderr
+++ b/src/test/ui/issues/issue-51244.stderr
@@ -8,3 +8,4 @@ LL |     *my_ref = 0;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/issues/issue-51515.stderr b/src/test/ui/issues/issue-51515.stderr
index 0e6c8fd48f19f..bcfed6d3bf88f 100644
--- a/src/test/ui/issues/issue-51515.stderr
+++ b/src/test/ui/issues/issue-51515.stderr
@@ -18,3 +18,4 @@ LL |     *bar = 64;
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/mut/mutable-class-fields-2.stderr b/src/test/ui/mut/mutable-class-fields-2.stderr
index a27a82ffe4642..15323ce9a9755 100644
--- a/src/test/ui/mut/mutable-class-fields-2.stderr
+++ b/src/test/ui/mut/mutable-class-fields-2.stderr
@@ -8,3 +8,4 @@ LL |     self.how_hungry -= 5;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/mut/mutable-class-fields.stderr b/src/test/ui/mut/mutable-class-fields.stderr
index 5391ccc80c5f9..40a0dc9b29c23 100644
--- a/src/test/ui/mut/mutable-class-fields.stderr
+++ b/src/test/ui/mut/mutable-class-fields.stderr
@@ -8,3 +8,4 @@ LL |   nyan.how_hungry = 0;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/nll/closure-captures.stderr b/src/test/ui/nll/closure-captures.stderr
index fbd02bc8095a7..c4b0bdc08c4f6 100644
--- a/src/test/ui/nll/closure-captures.stderr
+++ b/src/test/ui/nll/closure-captures.stderr
@@ -156,4 +156,5 @@ LL | |         *x = 1;});
 
 error: aborting due to 12 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/nll/constant-thread-locals-issue-47053.stderr b/src/test/ui/nll/constant-thread-locals-issue-47053.stderr
index 16a6e59e4da3a..ae056a9784085 100644
--- a/src/test/ui/nll/constant-thread-locals-issue-47053.stderr
+++ b/src/test/ui/nll/constant-thread-locals-issue-47053.stderr
@@ -6,3 +6,4 @@ LL |     FOO = 6;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/nll/generator-upvar-mutability.stderr b/src/test/ui/nll/generator-upvar-mutability.stderr
index 1b4e5b89984e7..31b061b61d19d 100644
--- a/src/test/ui/nll/generator-upvar-mutability.stderr
+++ b/src/test/ui/nll/generator-upvar-mutability.stderr
@@ -9,3 +9,4 @@ LL |         x = 1;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/nll/issue-47388.stderr b/src/test/ui/nll/issue-47388.stderr
index a5f5bf6ee2fdd..91f758a60a57e 100644
--- a/src/test/ui/nll/issue-47388.stderr
+++ b/src/test/ui/nll/issue-47388.stderr
@@ -8,3 +8,4 @@ LL |     fancy_ref.num = 6;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/nll/issue-51244.stderr b/src/test/ui/nll/issue-51244.stderr
index 6b543389af508..69efb2ca84751 100644
--- a/src/test/ui/nll/issue-51244.stderr
+++ b/src/test/ui/nll/issue-51244.stderr
@@ -8,3 +8,4 @@ LL |     *my_ref = 0;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/nll/issue-57989.stderr b/src/test/ui/nll/issue-57989.stderr
index 7367dc095a31a..d6bbbc317e0ab 100644
--- a/src/test/ui/nll/issue-57989.stderr
+++ b/src/test/ui/nll/issue-57989.stderr
@@ -20,4 +20,5 @@ LL |     g;
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0506`.
+Some errors have detailed explanations: E0506, E0594.
+For more information about an error, try `rustc --explain E0506`.
diff --git a/src/test/ui/rfc-2005-default-binding-mode/enum.stderr b/src/test/ui/rfc-2005-default-binding-mode/enum.stderr
index 9d53e6d7887df..d6a89006bc0fb 100644
--- a/src/test/ui/rfc-2005-default-binding-mode/enum.stderr
+++ b/src/test/ui/rfc-2005-default-binding-mode/enum.stderr
@@ -18,3 +18,4 @@ LL |         *x += 1;
 
 error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.stderr b/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.stderr
index 5eace3d263d46..a6f2f3ec30968 100644
--- a/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.stderr
+++ b/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.stderr
@@ -18,3 +18,4 @@ LL |             *n += 1;
 
 error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/suggestions/suggest-ref-mut.stderr b/src/test/ui/suggestions/suggest-ref-mut.stderr
index 3dd9fbc6f1480..9f00967d84089 100644
--- a/src/test/ui/suggestions/suggest-ref-mut.stderr
+++ b/src/test/ui/suggestions/suggest-ref-mut.stderr
@@ -35,3 +35,4 @@ LL |         ref quo => { *quo = 32; },
 
 error: aborting due to 4 previous errors
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/thread-local-mutation.stderr b/src/test/ui/thread-local-mutation.stderr
index 7f7738b5d6509..e5dc0e72edfc7 100644
--- a/src/test/ui/thread-local-mutation.stderr
+++ b/src/test/ui/thread-local-mutation.stderr
@@ -6,3 +6,4 @@ LL |     S = "after";
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/unboxed-closures/unboxed-closure-immutable-capture.stderr b/src/test/ui/unboxed-closures/unboxed-closure-immutable-capture.stderr
index 9fd8aa562f4e4..ad5451ced55d0 100644
--- a/src/test/ui/unboxed-closures/unboxed-closure-immutable-capture.stderr
+++ b/src/test/ui/unboxed-closures/unboxed-closure-immutable-capture.stderr
@@ -71,4 +71,5 @@ LL |     || set(&mut x);
 
 error: aborting due to 8 previous errors
 
-For more information about this error, try `rustc --explain E0596`.
+Some errors have detailed explanations: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.
diff --git a/src/test/ui/unboxed-closures/unboxed-closures-mutate-upvar.stderr b/src/test/ui/unboxed-closures/unboxed-closures-mutate-upvar.stderr
index fef6c23a50130..6bba38510b676 100644
--- a/src/test/ui/unboxed-closures/unboxed-closures-mutate-upvar.stderr
+++ b/src/test/ui/unboxed-closures/unboxed-closures-mutate-upvar.stderr
@@ -42,3 +42,4 @@ LL | |     });
 
 error: aborting due to 4 previous errors
 
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/unboxed-closures/unboxed-closures-mutated-upvar-from-fn-closure.stderr b/src/test/ui/unboxed-closures/unboxed-closures-mutated-upvar-from-fn-closure.stderr
index 2bc1f01af9815..a38c612e1dea9 100644
--- a/src/test/ui/unboxed-closures/unboxed-closures-mutated-upvar-from-fn-closure.stderr
+++ b/src/test/ui/unboxed-closures/unboxed-closures-mutated-upvar-from-fn-closure.stderr
@@ -16,3 +16,4 @@ LL | |     });
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0594`.