Make object init more robust (bug#69571)

* lisp/progmodes/csharp-mode.el (csharp-guess-basic-syntax): Make the
regex same as before, but conditionally check other heuristics rather
than crazy regex shenanigans.

lisp/progmodes/csharp-mode.el

@@ -500,7 +500,15 @@ compilation and evaluation time conflicts."
          ;; Also, deal with the possible end of line obscured by a
          ;; trailing comment.
          (goto-char (c-point 'iopl))
-         (looking-at "^[^//]*new[^//]*;$")))
+         (when (looking-at-p ".*new.*")
+           (if (re-search-forward ";" (pos-eol) t 1)
+               ;; If the ';' is inside a comment, the statement hasn't
+               ;; likely ended, so we should accept as object init.
+               ;; Example:
+               ;; var x = new         // This should return true ;
+               ;; var x = new();      // This should return false ;
+               (nth 4 (syntax-ppss (point)))
+             t))))
      ;; Line should not already be terminated
      (save-excursion
        (goto-char (c-point 'eopl))

test/lisp/progmodes/csharp-mode-resources/indent.erts

@@ -16,4 +16,82 @@ public class Foo {
         }  // [2]
     }
 }
+
+public class Foo {
+    void Bar () {
+        var x = new X();
+        for (;;) {
+            x();
+        }  // [2]
+    }
+}
+
+public class Foo {
+    void Bar () {
+        var x = new X()
+        {
+            var b = 3;
+        };
+        for (;;) {
+            x();
+        }  // [2]
+    }
+}
+
+public class Foo {
+    void Bar () {
+        var x = new X()              // Hello
+        {
+            var b = 3;
+        };
+        for (;;) {
+            x();
+        }  // [2]
+    }
+}
+
+public class Foo {
+    void Bar () {
+        var x = new X()              // Hello ;
+        {
+            var b = 3;
+        };
+        for (;;) {
+            x();
+        }  // [2]
+    }
+}
+
+public class Foo {
+    void Bar () {
+        var x = new X                // Hello ;
+        {
+            var b = 3;
+        };
+        for (;;) {
+            x();
+        }  // [2]
+    }
+}
+
+public class Foo {
+    void Bar () {
+        var x = new X();             // Hello ;
+        for (;;) {
+            x();
+        }  // [2]
+    }
+}
+
+public class Foo
+{
+    void Bar ()
+    {
+        var x = new X();             // Hello ;
+        for (;;)
+        {
+            x();
+        }  // [2]
+    }
+}
 =-=-=