[PATCH v6 0/1] MR10343: vbscript: Resolve parser conflicts with %prec and %expect.

[Francis De Brabandere (＠francisdb)]

Use %prec LOWER_THAN_ELSE on the empty EndIf_opt rule to explicitly
resolve 4 dangling Else / End If shift/reduce conflicts. The remaining
6 conflicts are benign colon-chain ambiguities documented with %expect 6.

--
  v6: vbscript: Resolve parser conflicts with %prec and %expect.
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10343

[PATCH v6 1/1] vbscript: Resolve parser conflicts with %prec and %expect.

[Francis De Brabandere]

From: Francis De Brabandere <[e-mail]>

Use %prec LOWER_THAN_ELSE on the empty EndIf_opt rule to explicitly
resolve 4 dangling Else / End If shift/reduce conflicts. The remaining
6 conflicts are benign colon-chain ambiguities documented with %expect 6.
---
 dlls/vbscript/parser.y | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/dlls/vbscript/parser.y b/dlls/vbscript/parser.y
index a7d95eaa707..2f178d189cc 100644
--- a/dlls/vbscript/parser.y
+++ b/dlls/vbscript/parser.y
@@ -94,6 +94,15 @@ static statement_t *link_statements(statement_t*,statement_t*);
 %define api.pure
 %start Program
 
+/* Resolve dangling Else / End If conflicts via precedence: the empty
+ * EndIf_opt rule gets lower precedence than tELSE and tEND so that
+ * shift (binding to innermost If) always wins. The remaining 6
+ * shift/reduce conflicts are benign colon-chain ambiguities where
+ * bison's default shift gives the correct greedy behavior. */
+%nonassoc LOWER_THAN_ELSE
+%nonassoc tELSE tEND
+%expect 6
+
 %union {
     const WCHAR *string;
     statement_t *statement;
@@ -321,7 +330,7 @@ IfStatement
                                                 { $$ = new_if_statement(ctx, @$, $2, $4, NULL, NULL); CHECK_ERROR; }
 
 EndIf_opt
-    : /* empty */
+    : /* empty */ %prec LOWER_THAN_ELSE
     | tEND tIF
 
 ElseIfs_opt
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10343