Add extended information for E0594

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
 }

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.

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`.