grep: -q match yields exit 0 even after a file error

src/searcher.rs

@@ -118,7 +118,12 @@ impl<'a> Searcher<'a> {
             .flush()
             .map_err_context(|| "(standard output)".to_string())?;
 
-        if self.had_error {
+        // With -q, a match yields exit status 0 even if an error (e.g. a
+        // missing file) occurred earlier: GNU exits as soon as a line is
+        // selected, so the error never affects the status.
+        if self.config.quiet && self.any_match {
+            Ok(())
+        } else if self.had_error {
             Err(ExitCode::new(2))
         } else if self.any_match {
             Ok(())

tests/test_grep.rs

@@ -126,6 +126,28 @@ fn ere_invalid_pattern_is_error() {
         .stderr_contains("invalid pattern");
 }
 
+#[test]
+fn quiet_match_overrides_file_error() {
+    // With -q, a match makes grep exit 0 even if an earlier file could not be
+    // opened. Without -q the missing file still yields exit 2, and -q with no
+    // match keeps the error status.
+    let (_s, mut c) = ucmd();
+    c.args(&["-q", "abc", "no-such-file", "-"])
+        .pipe_in("abcd\n")
+        .succeeds()
+        .no_output();
+
+    let (_s, mut c) = ucmd();
+    c.args(&["abc", "no-such-file", "-"])
+        .pipe_in("abcd\n")
+        .fails_with_code(2);
+
+    let (_s, mut c) = ucmd();
+    c.args(&["-q", "zzz", "no-such-file", "-"])
+        .pipe_in("abcd\n")
+        .fails_with_code(2);
+}
+
 #[test]
 fn initial_tab_skips_empty_lines() {
     // -T aligns content with a tab, but GNU omits the tab for an empty line