--posix should reject GNU substitute flags i/I #401

src/sed/compiler.rs

@@ -32,6 +32,8 @@ const DEFAULT_OUTPUT_WIDTH: usize = 60;
 const ERR_ADDRESS_0_USAGE: &str =
     "address 0 can only be used with ~step, a second regular expression, or a read command";
 
+const ERR_UNKNOWN_OPTION_TO_S: &str = "unknown option to 's'";
+
 // Handling required after processing a command
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum CommandHandling {
@@ -918,10 +920,19 @@ pub fn compile_subst_flags(
             }
 
             'i' | 'I' => {
+                if posix {
+                    return compilation_error(lines, line, ERR_UNKNOWN_OPTION_TO_S);
+                }
                 subst.ignore_case = true;
                 line.advance();
             }
 
+            'm' | 'M' => {
+                if posix {
+                    return compilation_error(lines, line, ERR_UNKNOWN_OPTION_TO_S);
+                }
+            }
+
             'e' => {
                 if posix || sandbox {
                     return compilation_error(

tests/by-util/test_sed.rs

@@ -1604,3 +1604,19 @@ fn test_print_first_line_no_newline() {
         .succeeds()
         .stdout_is("foo");
 }
+
+//--posix should reject GNU substitute flags i/I https://github.com/uutils/sed/issues/401
+#[test]
+fn test_posix_reject_flags() {
+    new_ucmd!()
+        .args(&["--posix", "s/a/b/i"])
+        .fails()
+        .code_is(1)
+        .stderr_is("sed: <script argument 1>:1:7: error: unknown option to 's'\n");
+
+    new_ucmd!()
+        .args(&["--posix", "s/a/b/m"])
+        .fails()
+        .code_is(1)
+        .stderr_is("sed: <script argument 1>:1:7: error: unknown option to 's'\n");
+}