3 files changed, 41 insertions, 1 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes.rs b/compiler/rustc_error_codes/src/error_codes.rs
index 072b0f2fcce..800f3c52177 100644
--- a/compiler/rustc_error_codes/src/error_codes.rs
+++ b/compiler/rustc_error_codes/src/error_codes.rs
@@ -286,6 +286,7 @@ E0519: include_str!("./error_codes/E0519.md"),
 E0520: include_str!("./error_codes/E0520.md"),
 E0521: include_str!("./error_codes/E0521.md"),
 E0522: include_str!("./error_codes/E0522.md"),
+E0523: include_str!("./error_codes/E0523.md"),
 E0524: include_str!("./error_codes/E0524.md"),
 E0525: include_str!("./error_codes/E0525.md"),
 E0527: include_str!("./error_codes/E0527.md"),
@@ -622,7 +623,6 @@ E0793: include_str!("./error_codes/E0793.md"),
 //  E0488, // lifetime of variable does not enclose its declaration
 //  E0489, // type/lifetime parameter not in scope here
 //  E0490, // removed: unreachable
-    E0523, // two dependencies have same (crate-name, disambiguator) but different SVH
 //  E0526, // shuffle indices are not constant
 //  E0540, // multiple rustc_deprecated attributes
 //  E0548, // replaced with a generic attribute input check
diff --git a/compiler/rustc_error_codes/src/error_codes/E0464.md b/compiler/rustc_error_codes/src/error_codes/E0464.md
index 9108d856c9d..209cbb00db5 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0464.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0464.md
@@ -1,6 +1,21 @@
 The compiler found multiple library files with the requested crate name.
 
+```compile_fail
+// aux-build:crateresolve-1.rs
+// aux-build:crateresolve-2.rs
+// aux-build:crateresolve-3.rs
+
+extern crate crateresolve;
+//~^ ERROR multiple candidates for `rlib` dependency `crateresolve` found
+
+fn main() {}
+```
+
 This error can occur in several different cases -- for example, when using
 `extern crate` or passing `--extern` options without crate paths. It can also be
 caused by caching issues with the build directory, in which case `cargo clean`
 may help.
+
+In the above example, there are three different library files, all of which
+define the same crate name. Without providing a full path, there is no way for
+the compiler to know which crate it should use.
diff --git a/compiler/rustc_error_codes/src/error_codes/E0523.md b/compiler/rustc_error_codes/src/error_codes/E0523.md
new file mode 100644
index 00000000000..0ddf70386c2
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0523.md
@@ -0,0 +1,25 @@
+#### Note: this error code is no longer emitted by the compiler.
+
+The compiler found multiple library files with the requested crate name.
+
+```compile_fail
+// aux-build:crateresolve-1.rs
+// aux-build:crateresolve-2.rs
+// aux-build:crateresolve-3.rs
+
+extern crate crateresolve;
+//~^ ERROR multiple candidates for `rlib` dependency `crateresolve` found
+
+fn main() {}
+```
+
+This error can occur in several different cases -- for example, when using
+`extern crate` or passing `--extern` options without crate paths. It can also be
+caused by caching issues with the build directory, in which case `cargo clean`
+may help.
+
+In the above example, there are three different library files, all of which
+define the same crate name. Without providing a full path, there is no way for
+the compiler to know which crate it should use.
+
+*Note that E0523 has been merged into E0464.*