Differentiate between cargo and non-cargo runs

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;
@@ -2045,10 +2046,17 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                             self.current_crate_outer_attr_insert_span,
                             format!("extern crate {ident};\n"),
                         )],
-                        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",
-                        ),
+                        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,
                     )),
                 )
@@ -2227,14 +2235,24 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 let descr = binding.res().descr();
                 (format!("{descr} `{ident}` is not a crate or module"), suggestion)
             } else {
-                let suggestion = suggestion.or(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,
-                )));
+                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)
             }
         }

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

@@ -4,7 +4,7 @@ error[E0433]: failed to resolve: use of unresolved module or unlinked crate `non
 LL |     pub(in nonexistent) field: u8
    |            ^^^^^^^^^^^ use of unresolved module or unlinked crate `nonexistent`
    |
-help: if you wanted to use a crate named `nonexistent`, use `cargo add nonexistent` to add it to your `Cargo.toml` and import it in your code
+help: you might be missing a crate named `nonexistent`, add it to your project and import it in your code
    |
 LL + extern crate nonexistent;
    |
@@ -15,7 +15,7 @@ error[E0433]: failed to resolve: use of unresolved module or unlinked crate `non
 LL |     pub(in nonexistent) u8
    |            ^^^^^^^^^^^ use of unresolved module or unlinked crate `nonexistent`
    |
-help: if you wanted to use a crate named `nonexistent`, use `cargo add nonexistent` to add it to your `Cargo.toml` and import it in your code
+help: you might be missing a crate named `nonexistent`, add it to your project and import it in your code
    |
 LL + extern crate nonexistent;
    |