BR3392240: preproc: Don't fail on pasting of space expanded rvalue tokens

Reported-by: KO Myung-Hun <komh@chollian.net>
Tested-by: KO Myung-Hun <komh@chollian.net>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

1 files changed, 25 insertions, 4 deletions

diff --git a/preproc.c b/preproc.c
index 9d659174..0ca360ed 100644
--- a/preproc.c
+++ b/preproc.c
@@ -3640,14 +3640,35 @@ static bool paste_tokens(Token **head, const struct tokseq_match *m,
             if (!pasted)
                 pasted = true;
 
-            /* No ending token */
-            if (!next)
-                error(ERR_FATAL, "No rvalue found on pasting");
-
             /* Left pasting token is start of line */
             if (!prev_nonspace)
                 error(ERR_FATAL, "No lvalue found on pasting");
 
+            /*
+             * No ending token, this might happen in two
+             * cases
+             *
+             *  1) There indeed no right token at all
+             *  2) There is a bare "%define ID" statement,
+             *     and @ID does expand to whitespace.
+             *
+             * So technically we need to do a grammar analysis
+             * in another stage of parsing, but for now lets don't
+             * change the behaviour people used to. Simply allow
+             * whitespace after paste token.
+             */
+            if (!next) {
+                /*
+                 * Zap ending space tokens and that's all.
+                 */
+                tok = (*prev_nonspace)->next;
+                while (tok_type_(tok, TOK_WHITESPACE))
+                    tok = delete_Token(tok);
+                tok = *prev_nonspace;
+                tok->next = NULL;
+                break;
+            }
+
             tok = *prev_nonspace;
             while (tok_type_(tok, TOK_WHITESPACE))
                 tok = delete_Token(tok);