Reword "crate not found" resolve message

```
error[E0432]: unresolved import `some_novel_crate`
 --> file.rs:1:5
  |
1 | use some_novel_crate::Type;
  |     ^^^^^^^^^^^^^^^^ use of unresolved module or unlinked crate `some_novel_crate`
```

On resolve errors where there might be a missing crate, mention `cargo add foo`:

```
error[E0433]: failed to resolve: use of unresolved module or unlinked crate `nope`
  --> $DIR/conflicting-impl-with-err.rs:4:11
   |
LL | impl From<nope::Thing> for Error {
   |           ^^^^ use of unresolved module or unlinked crate `nope`
   |
   = help: if you wanted to use a crate named `nope`, use `cargo add nope` to add it to your `Cargo.toml`
```

Author: estebank

compiler/rustc_resolve/src/diagnostics.rs

@@ -24,6 +24,7 @@ use rustc_session::lint::builtin::{
     MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
 };
 use rustc_session::lint::{AmbiguityErrorDiag, BuiltinLintDiag};
+use rustc_session::utils::was_invoked_from_cargo;
 use rustc_span::edit_distance::find_best_match_for_name;
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::MacroKind;
@@ -809,7 +810,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     }
                     err.multipart_suggestion(msg, suggestions, applicability);
                 }
-
                 if let Some(ModuleOrUniformRoot::Module(module)) = module
                     && let Some(module) = module.opt_def_id()
                     && let Some(segment) = segment
@@ -2044,13 +2044,23 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 (format!("`_` is not a valid crate or module name"), None)
             } else if self.tcx.sess.is_rust_2015() {
                 (
-                    format!("you might be missing crate `{ident}`"),
+                    format!("use of unresolved module or unlinked crate `{ident}`"),
                     Some((
                         vec![(
                             self.current_crate_outer_attr_insert_span,
                             format!("extern crate {ident};\n"),
                         )],
-                        format!("consider importing the `{ident}` crate"),
+                        if was_invoked_from_cargo() {
+                            format!(
+                                "if you wanted to use a crate named `{ident}`, use `cargo add {ident}` \
+                             to add it to your `Cargo.toml` and import it in your code",
+                            )
+                        } else {
+                            format!(
+                                "you might be missing a crate named `{ident}`, add it to your \
+                                 project and import it in your code",
+                            )
+                        },
                         Applicability::MaybeIncorrect,
                     )),
                 )
@@ -2229,7 +2239,25 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 let descr = binding.res().descr();
                 (format!("{descr} `{ident}` is not a crate or module"), suggestion)
             } else {
-                (format!("use of undeclared crate or module `{ident}`"), suggestion)
+                let suggestion = if suggestion.is_some() {
+                    suggestion
+                } else if was_invoked_from_cargo() {
+                    Some((
+                        vec![],
+                        format!(
+                            "if you wanted to use a crate named `{ident}`, use `cargo add {ident}` \
+                             to add it to your `Cargo.toml`",
+                        ),
+                        Applicability::MaybeIncorrect,
+                    ))
+                } else {
+                    Some((
+                        vec![],
+                        format!("you might be missing a crate named `{ident}`",),
+                        Applicability::MaybeIncorrect,
+                    ))
+                };
+                (format!("use of unresolved module or unlinked crate `{ident}`"), suggestion)
             }
         }
     }

src/tools/miri/tests/fail/rustc-error2.rs

@@ -4,7 +4,7 @@ struct Struct<T>(T);
 impl<T> std::ops::Deref for Struct<T> {
     type Target = dyn Fn(T);
     fn deref(&self) -> &assert_mem_uninitialized_valid::Target {
-        //~^ERROR: undeclared crate or module
+        //~^ERROR: use of unresolved module or unlinked crate
         unimplemented!()
     }
 }

src/tools/miri/tests/fail/rustc-error2.stderr

@@ -1,8 +1,10 @@
-error[E0433]: failed to resolve: use of undeclared crate or module `assert_mem_uninitialized_valid`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `assert_mem_uninitialized_valid`
   --> tests/fail/rustc-error2.rs:LL:CC
    |
 LL |     fn deref(&self) -> &assert_mem_uninitialized_valid::Target {
-   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ use of undeclared crate or module `assert_mem_uninitialized_valid`
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ use of unresolved module or unlinked crate `assert_mem_uninitialized_valid`
+   |
+   = help: you might be missing a crate named `assert_mem_uninitialized_valid`
 
 error: aborting due to 1 previous error
 

tests/rustdoc-ui/ice-unresolved-import-100241.stderr

@@ -2,9 +2,9 @@ error[E0432]: unresolved import `inner`
   --> $DIR/ice-unresolved-import-100241.rs:9:13
    |
 LL |     pub use inner::S;
-   |             ^^^^^ you might be missing crate `inner`
+   |             ^^^^^ use of unresolved module or unlinked crate `inner`
    |
-help: consider importing the `inner` crate
+help: you might be missing a crate named `inner`, add it to your project and import it in your code
    |
 LL + extern crate inner;
    |

tests/rustdoc-ui/intra-doc/unresolved-import-recovery.stderr

@@ -1,10 +1,10 @@
-error[E0433]: failed to resolve: you might be missing crate `unresolved_crate`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `unresolved_crate`
   --> $DIR/unresolved-import-recovery.rs:3:5
    |
 LL | use unresolved_crate::module::Name;
-   |     ^^^^^^^^^^^^^^^^ you might be missing crate `unresolved_crate`
+   |     ^^^^^^^^^^^^^^^^ use of unresolved module or unlinked crate `unresolved_crate`
    |
-help: consider importing the `unresolved_crate` crate
+help: you might be missing a crate named `unresolved_crate`, add it to your project and import it in your code
    |
 LL + extern crate unresolved_crate;
    |

tests/rustdoc-ui/issues/issue-61732.rs

@@ -1,4 +1,4 @@
 // This previously triggered an ICE.
 
 pub(in crate::r#mod) fn main() {}
-//~^ ERROR failed to resolve: you might be missing crate `r#mod`
+//~^ ERROR failed to resolve: use of unresolved module or unlinked crate `r#mod`

tests/rustdoc-ui/issues/issue-61732.stderr

@@ -1,10 +1,10 @@
-error[E0433]: failed to resolve: you might be missing crate `r#mod`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `r#mod`
   --> $DIR/issue-61732.rs:3:15
    |
 LL | pub(in crate::r#mod) fn main() {}
-   |               ^^^^^ you might be missing crate `r#mod`
+   |               ^^^^^ use of unresolved module or unlinked crate `r#mod`
    |
-help: consider importing the `r#mod` crate
+help: you might be missing a crate named `r#mod`, add it to your project and import it in your code
    |
 LL + extern crate r#mod;
    |

tests/ui/attributes/check-builtin-attr-ice.stderr

@@ -1,20 +1,20 @@
-error[E0433]: failed to resolve: use of undeclared crate or module `should_panic`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `should_panic`
   --> $DIR/check-builtin-attr-ice.rs:43:7
    |
 LL |     #[should_panic::skip]
-   |       ^^^^^^^^^^^^ use of undeclared crate or module `should_panic`
+   |       ^^^^^^^^^^^^ use of unresolved module or unlinked crate `should_panic`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `should_panic`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `should_panic`
   --> $DIR/check-builtin-attr-ice.rs:47:7
    |
 LL |     #[should_panic::a::b::c]
-   |       ^^^^^^^^^^^^ use of undeclared crate or module `should_panic`
+   |       ^^^^^^^^^^^^ use of unresolved module or unlinked crate `should_panic`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `deny`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `deny`
   --> $DIR/check-builtin-attr-ice.rs:55:7
    |
 LL |     #[deny::skip]
-   |       ^^^^ use of undeclared crate or module `deny`
+   |       ^^^^ use of unresolved module or unlinked crate `deny`
 
 error: aborting due to 3 previous errors
 

tests/ui/attributes/check-cfg_attr-ice.stderr

@@ -17,83 +17,83 @@ LL |         #[cfg_attr::no_such_thing]
    = help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:52:3
    |
 LL | #[cfg_attr::no_such_thing]
-   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |   ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:55:7
    |
 LL |     #[cfg_attr::no_such_thing]
-   |       ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |       ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:57:17
    |
 LL |     GiveYouUp(#[cfg_attr::no_such_thing] u8),
-   |                 ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |                 ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:64:11
    |
 LL |         #[cfg_attr::no_such_thing]
-   |           ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |           ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:41:7
    |
 LL |     #[cfg_attr::no_such_thing]
-   |       ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |       ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:43:15
    |
 LL |     fn from(#[cfg_attr::no_such_thing] any_other_guy: AnyOtherGuy) -> This {
-   |               ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |               ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:45:11
    |
 LL |         #[cfg_attr::no_such_thing]
-   |           ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |           ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:32:3
    |
 LL | #[cfg_attr::no_such_thing]
-   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |   ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:24:3
    |
 LL | #[cfg_attr::no_such_thing]
-   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |   ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:27:7
    |
 LL |     #[cfg_attr::no_such_thing]
-   |       ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |       ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:16:3
    |
 LL | #[cfg_attr::no_such_thing]
-   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |   ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:19:7
    |
 LL |     #[cfg_attr::no_such_thing]
-   |       ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |       ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
-error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `cfg_attr`
   --> $DIR/check-cfg_attr-ice.rs:12:3
    |
 LL | #[cfg_attr::no_such_thing]
-   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+   |   ^^^^^^^^ use of unresolved module or unlinked crate `cfg_attr`
 
 error: aborting due to 15 previous errors
 

tests/ui/attributes/field-attributes-vis-unresolved.stderr

@@ -1,21 +1,21 @@
-error[E0433]: failed to resolve: you might be missing crate `nonexistent`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `nonexistent`
   --> $DIR/field-attributes-vis-unresolved.rs:17:12
    |
 LL |     pub(in nonexistent) field: u8
-   |            ^^^^^^^^^^^ you might be missing crate `nonexistent`
+   |            ^^^^^^^^^^^ use of unresolved module or unlinked crate `nonexistent`
    |
-help: consider importing the `nonexistent` crate
+help: you might be missing a crate named `nonexistent`, add it to your project and import it in your code
    |
 LL + extern crate nonexistent;
    |
 
-error[E0433]: failed to resolve: you might be missing crate `nonexistent`
+error[E0433]: failed to resolve: use of unresolved module or unlinked crate `nonexistent`
   --> $DIR/field-attributes-vis-unresolved.rs:22:12
    |
 LL |     pub(in nonexistent) u8
-   |            ^^^^^^^^^^^ you might be missing crate `nonexistent`
+   |            ^^^^^^^^^^^ use of unresolved module or unlinked crate `nonexistent`
    |
-help: consider importing the `nonexistent` crate
+help: you might be missing a crate named `nonexistent`, add it to your project and import it in your code
    |
 LL + extern crate nonexistent;
    |