[flang] Extend documentation on extensions.

Original-commit: flang-compiler/f18@672e468252b221d53e5b87aad805b42820b2bfff
Reviewed-on: https://github.com/flang-compiler/f18/pull/122

diff --git a/flang/documentation/extensions.md b/flang/documentation/extensions.md
index 62e0b08..ad4807f 100644 (file)
--- a/flang/documentation/extensions.md
+++ b/flang/documentation/extensions.md
@@ -44,6 +44,8 @@ Extensions, deletions, and legacy features supported
 * Backslash escape character sequences in quoted character literals
 * `D` lines in fixed form as comments or debug code
 * `CONVERT=` on the OPEN statement
+* Leading semicolons are ignored before any statement that
+  could have a label
 
 Extensions and legacy features deliberately not supported
 ---------------------------------------------------------