Auto merge of #6767 - ehuss:fix-git-ignore-of-root, r=Eh2406

Allow `cargo fix` if gitignore matches root working dir.

If `.gitignore` had a rule that matched the root working directory, it would believe that the whole thing is ignored. This is not usually how git works (AFAIK), so don't check gitignore against the root.

Closes #6766

src/cargo/util/vcs.rs

@@ -13,9 +13,12 @@ use crate::util::{process, CargoResult};
 pub fn existing_vcs_repo(path: &Path, cwd: &Path) -> bool {
     fn in_git_repo(path: &Path, cwd: &Path) -> bool {
         if let Ok(repo) = GitRepo::discover(path, cwd) {
-            repo.is_path_ignored(path)
-                .map(|ignored| !ignored)
-                .unwrap_or(true)
+            // Don't check if the working directory itself is ignored.
+            if repo.workdir().map_or(false, |workdir| workdir == path) {
+                true
+            } else {
+                !repo.is_path_ignored(path).unwrap_or(false)
+            }
         } else {
             false
         }

tests/testsuite/fix.rs

@@ -1289,3 +1289,26 @@ fn fix_with_common() {
 
     assert_eq!(p.read_file("tests/common/mod.rs"), "pub fn r#try() {}");
 }
+
+#[test]
+fn fix_in_existing_repo_weird_ignore() {
+    // Check that ignore doesn't ignore the repo itself.
+    let p = git::new("foo", |project| {
+        project
+            .file("src/lib.rs", "")
+            .file(".gitignore", "foo\ninner\n")
+            .file("inner/file", "")
+    })
+    .unwrap();
+
+    p.cargo("fix").run();
+    // This is questionable about whether it is the right behavior. It should
+    // probably be checking if any source file for the current project is
+    // ignored.
+    p.cargo("fix")
+        .cwd(p.root().join("inner"))
+        .with_stderr_contains("[ERROR] no VCS found[..]")
+        .with_status(101)
+        .run();
+    p.cargo("fix").cwd(p.root().join("src")).run();
+}