Add diagnostics for rustc_metadata

src/librustc_driver/lib.rs

@@ -1112,6 +1112,7 @@ pub fn diagnostics_registry() -> errors::registry::Registry {
     all_errors.extend_from_slice(&rustc_privacy::DIAGNOSTICS);
     all_errors.extend_from_slice(&rustc_trans::DIAGNOSTICS);
     all_errors.extend_from_slice(&rustc_const_eval::DIAGNOSTICS);
+    all_errors.extend_from_slice(&rustc_metadata::DIAGNOSTICS);
 
     Registry::new(&all_errors)
 }

src/librustc_metadata/diagnostics.rs

@@ -91,6 +91,197 @@ You need to link your code to the relevant crate in order to be able to use it
 well, and you link to them the same way.
 "##,
 
+E0466: r##"
+Invalid macro import declarations.
+
+This is a syntax error at the level of attribute declarations.
+
+Causes of this error:
+
+```ignore
+#[macro_use(a_macro(another_macro))]    // error: invalid import declaration
+extern crate some_crate;
+
+#[macro_use(i_want = "some_macros")]    // error: invalid import declaration
+extern crate another_crate;
+```
+
+Macro imports are properly declared as:
+
+```ignore
+#[macro_use(get_tacos, bring_beer)]     // imports macros get_tacos and 
+extern crate some_crate;                // bring_beer from some_crate
+```
+
+Declaring `macro_use` with no arguments will import all available macros from 
+the given crate.
+
+Exported macros must be declared as such with `macro_export`. In the above 
+example, some_crate would contain:
+
+```ignore
+#[macro_export]
+macro_rules! get_tacos {
+    ...
+}
+
+#[macro_export]
+macro_rules! bring_beer {
+    ...
+}
+```
+
+"##,
+
+E0467: r##"
+Invalid or no macros listed for reexport.
+
+This is a syntax error at the level of attribute declarations.
+
+Causes of this error:
+
+```ignore
+#[macro_reexport] // error: no macros listed for export
+extern crate macros_for_good;
+```
+```ignore
+#[macro_reexport(fun_macro = "foo")] // error: not a macro identifier
+extern crate macros_for_good;
+```
+
+Currently, `macro_reexport` requires at least one macro name to be listed. 
+Unlike `macro_use`, listing no names does not reexport all macros from the 
+given crate.
+
+Decide which macros you would like to export and list them properly.
+"##,
+
+E0468: r##"
+A non-root module attempts to import macros from another crate.
+
+```ignore
+mod foo {
+    #[macro_use(helpful_macro)] // error: must be at crate root to import
+    extern crate some_crate;    //        macros from another crate
+    helpful_macro!(...)
+}
+
+fn main() {
+    // ...
+}
+```
+
+Only `extern crate` imports at the crate root level (i.e., in lib.rs) are 
+allowed to import macros.
+
+Either move the macro import to crate root or do without the foreign macros.
+
+This will work: 
+
+```ignore
+#[macro_use(helpful_macro)]
+extern crate some_crate;
+mod foo {
+    helpful_macro!(...)
+}
+
+fn main() {
+    //...
+}
+```
+
+"##,
+
+E0469: r##"
+A macro listed for import was not found.
+
+Either the listed macro is not contained in the imported crate, or it is not
+exported from the given crate.
+
+```ignore
+/// // crate some_crate contains:
+/// #[macro_export]
+/// macro_rules! eat {
+///     ...
+/// }
+/// macro_rules! drink {
+///     ...
+/// }
+
+// error: drink is a private macro of some_crate
+// error: be_merry does not exist in some_crate
+#[macro_use(drink, be_merry)]
+extern crate some_crate;
+```
+
+This could be caused by a typo. Did you misspell the macro's name?
+
+Double-check the names of the macros listed for import, and that the crate 
+in question exports them.
+
+A working version of the above:
+
+```ignore
+/// // crate some_crate contains:
+/// #[macro_export]
+/// macro_rules! eat {
+///     ...
+/// }
+/// #[macro_export]
+/// macro_rules! drink {
+///     ...
+/// }
+
+#[macro_use(eat, drink)]
+extern crate some_crate;
+```
+"##,
+
+E0470: r##"
+A macro listed for reexport was not found.
+
+Either the listed macro is not contained in the imported crate, or it is not
+exported from the given crate.
+
+```ignore
+/// // crate some_crate contains:
+/// #[macro_export]
+/// macro_rules! eat {
+///     ...
+/// }
+/// macro_rules! drink {
+///     ...
+/// }
+
+// error: drink is a private macro of some_crate
+// error: be_merry does not exist in some_crate
+#[macro_reexport(drink, be_merry)]
+extern crate some_crate;
+```
+
+This could be caused by a typo. Did you misspell the macro's name?
+
+Double-check the names of the macros listed for reexport, and that the crate 
+in question exports them.
+
+A working version of the above:
+
+```ignore
+/// // crate some_crate contains:
+/// #[macro_export]
+/// macro_rules! eat {
+///     ...
+/// }
+/// #[macro_export]
+/// macro_rules! drink {
+///     ...
+/// }
+
+#[macro_reexport(eat, drink)]
+extern crate some_crate;
+```
+"##,
+
 }
 
 register_diagnostics! {
@@ -102,11 +293,6 @@ register_diagnostics! {
     E0462, // found staticlib `..` instead of rlib or dylib
     E0464, // multiple matching crates for `..`
     E0465, // multiple .. candidates for `..` found
-    E0466, // bad macro import
-    E0467, // bad macro reexport
-    E0468, // an `extern crate` loading macros must be at the crate root
-    E0469, // imported macro not found
-    E0470, // reexported macro not found
     E0519, // local crate and dependency have same (crate-name, disambiguator)
     E0523, // two dependencies have same (crate-name, disambiguator) but different SVH
 }

src/librustc_metadata/lib.rs

@@ -62,3 +62,5 @@ pub mod index;
 pub mod loader;
 pub mod macro_import;
 pub mod tls_context;
+
+__build_diagnostic_array! { librustc_metadata, DIAGNOSTICS }