fix(add): Lookup existing dependencies with fuzzy logic

Fixes rust-lang#10680
Fixes rust-lang#13702

src/cargo/ops/cargo_add/mod.rs

@@ -361,7 +361,9 @@ fn resolve_dependency(
     };
     selected_dep = populate_dependency(selected_dep, arg);
 
-    let old_dep = get_existing_dependency(manifest, selected_dep.toml_key(), section)?;
+    let lookup = |dep_key: &_| get_existing_dependency(manifest, dep_key, section);
+    let old_dep = fuzzy_lookup(&mut selected_dep, lookup, gctx)?;
+
     let mut dependency = if let Some(mut old_dep) = old_dep.clone() {
         if old_dep.name != selected_dep.name {
             // Assuming most existing keys are not relevant when the package changes
@@ -383,7 +385,8 @@ fn resolve_dependency(
     if dependency.source().is_none() {
         // Checking for a workspace dependency happens first since a member could be specified
         // in the workspace dependencies table as a dependency
-        if let Some(_dep) = find_workspace_dep(dependency.toml_key(), ws.root_manifest()).ok() {
+        let lookup = |toml_key: &_| Ok(find_workspace_dep(toml_key, ws.root_manifest()).ok());
+        if let Some(_dep) = fuzzy_lookup(&mut dependency, lookup, gctx)? {
             dependency = dependency.set_source(WorkspaceSource::new());
         } else if let Some(package) = ws.members().find(|p| p.name().as_str() == dependency.name) {
             // Only special-case workspaces when the user doesn't provide any extra
@@ -449,6 +452,40 @@ fn resolve_dependency(
     Ok(dependency)
 }
 
+fn fuzzy_lookup(
+    dependency: &mut Dependency,
+    lookup: impl Fn(&str) -> CargoResult<Option<Dependency>>,
+    gctx: &GlobalContext,
+) -> CargoResult<Option<Dependency>> {
+    if let Some(rename) = dependency.rename() {
+        return lookup(rename);
+    }
+
+    for name_permutation in [
+        dependency.name.clone(),
+        dependency.name.replace('-', "_"),
+        dependency.name.replace('_', "-"),
+    ] {
+        let Some(dep) = lookup(&name_permutation)? else {
+            continue;
+        };
+
+        if dependency.name != name_permutation {
+            if !matches!(dep.source, Some(Source::Registry(_))) {
+                continue;
+            }
+            gctx.shell().warn(format!(
+                "translating `{}` to `{}`",
+                dependency.name, &name_permutation,
+            ))?;
+            dependency.name = name_permutation;
+        }
+        return Ok(Some(dep));
+    }
+
+    Ok(None)
+}
+
 /// When { workspace = true } you cannot define other keys that configure
 /// the source of the dependency such as `version`, `registry`, `registry-index`,
 /// `path`, `git`, `branch`, `tag`, `rev`, or `package`. You can also not define

tests/testsuite/cargo_add/detect_workspace_inherit_fuzzy/out/primary/Cargo.toml

@@ -4,4 +4,4 @@ version = "0.0.0"
 edition = "2015"
 
 [dependencies]
-fuzzy_dependency = "1.0.0"
+fuzzy_dependency.workspace = true

tests/testsuite/cargo_add/features_fuzzy/out/Cargo.toml

@@ -6,4 +6,4 @@ version = "0.0.0"
 edition = "2015"
 
 [dependencies]
-your_face = { version = "99999.0.0" }
+your_face = { version = "99999.0.0", features = ["eyes"] }