Add suggestion to check block delimiter

The fix for #217 means that blocks of target code delimited by { } with
'#' comments in now give errors (previously these lines were quietly
discarded).

The fix is generally to use %{ %} delimiters instead, so suggest this
might be the issue in the error message to help users hitting this issue
with wrappers which were apparently working before.

2 files changed, 2 insertions, 2 deletions

diff --git a/Examples/test-suite/errors/pp_unknowndirective2.stderr b/Examples/test-suite/errors/pp_unknowndirective2.stderr
index 8244c7d0d..70afa670c 100644
--- a/Examples/test-suite/errors/pp_unknowndirective2.stderr
+++ b/Examples/test-suite/errors/pp_unknowndirective2.stderr
@@ -1 +1 @@
-pp_unknowndirective2.i:7: Error: Unknown SWIG preprocessor directive: elsif
+pp_unknowndirective2.i:7: Error: Unknown SWIG preprocessor directive: elsif (if this is a block of target language code, delimit it with %{ and %})
diff --git a/Source/Preprocessor/cpp.c b/Source/Preprocessor/cpp.c
index 8fd30f703..ac912f49e 100644
--- a/Source/Preprocessor/cpp.c
+++ b/Source/Preprocessor/cpp.c
@@ -1771,7 +1771,7 @@ String *Preprocessor_parse(String *s) {
       } else if (Equal(id, "")) {
 	/* Null directive */
       } else {
-	Swig_error(Getfile(s), Getline(id), "Unknown SWIG preprocessor directive: %s\n", id);
+	Swig_error(Getfile(s), Getline(id), "Unknown SWIG preprocessor directive: %s (if this is a block of target language code, delimit it with %%{ and %%})\n", id);
       }
       for (i = 0; i < cpp_lines; i++)
 	Putc('\n', ns);