[PATCH v4 0/1] MR10333: Draft: vbscript: Refactor ElseIf and Else grammar rules to avoid reduce/reduce conflicts.

[Francis De Brabandere (＠francisdb)]

Introduce StatementsBody, InlineStatements and InlineStatements_opt
non-terminals whose FIRST sets do not overlap with StSep. This allows
splitting ElseIf into multi-line (strict, requires statement separator)
and inline (lenient, allows trailing End If) forms, and splitting
Else_opt into separator and inline forms that naturally reject
"Else End If" without a semantic check.

--
  v4: vbscript: Refactor ElseIf and Else grammar rules to avoid reduce/reduce conflicts.
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10333

[PATCH v4 1/1] vbscript: Refactor ElseIf and Else grammar rules to avoid reduce/reduce conflicts.

[Francis De Brabandere]

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

Introduce StatementsBody, InlineStatements and InlineStatements_opt
non-terminals whose FIRST sets do not overlap with StSep. This allows
splitting ElseIf into multi-line (strict, requires statement separator)
and inline (lenient, allows trailing End If) forms, and splitting
Else_opt into separator and inline forms that naturally reject
"Else End If" without a semantic check.

The grammar now compiles with zero shift/reduce and zero reduce/reduce
conflicts.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55196
---
 dlls/vbscript/parser.y       | 26 +++++++++++++++---
 dlls/vbscript/tests/lang.vbs | 53 ++++++++++++++++++++++++++++++++++++
 dlls/vbscript/tests/run.c    | 15 ++++++++++
 3 files changed, 90 insertions(+), 4 deletions(-)

diff --git a/dlls/vbscript/parser.y b/dlls/vbscript/parser.y
index c5d2764562e..f0ff3b552d4 100644
--- a/dlls/vbscript/parser.y
+++ b/dlls/vbscript/parser.y
@@ -137,7 +137,7 @@ static statement_t *link_statements(statement_t*,statement_t*);
 %token <date> tDate
 
 %type <statement> Statement SimpleStatement StatementNl StatementsNl StatementsNl_opt BodyStatements IfStatement Else_opt
-%type <statement> GlobalDimDeclaration
+%type <statement> GlobalDimDeclaration StatementsBody InlineStatements InlineStatements_opt
 %type <expression> Expression LiteralExpression PrimaryExpression EqualityExpression CallExpression ExpressionNl_opt
 %type <expression> ConcatExpression AdditiveExpression ModExpression IntdivExpression MultiplicativeExpression ExpExpression
 %type <expression> NotExpression UnaryExpression AndExpression OrExpression XorExpression EqvExpression SignExpression
@@ -325,12 +325,30 @@ ElseIfs
     | ElseIf ElseIfs                        { $1->next = $2; $$ = $1; }
 
 ElseIf
-    : tELSEIF Expression tTHEN StSep_opt StatementsNl_opt
-                                            { $$ = new_elseif_decl(ctx, @$, $2, $5); }
+    : tELSEIF Expression tTHEN StSep StatementsNl_opt
+                                             { $$ = new_elseif_decl(ctx, @$, $2, $5); }
+    | tELSEIF Expression tTHEN InlineStatements_opt
+                                             { $$ = new_elseif_decl(ctx, @$, $2, $4); }
 
 Else_opt
     : /* empty */                           { $$ = NULL; }
-    | tELSE StSep_opt StatementsNl_opt      { $$ = $3; }
+    | tELSE StSep StatementsBody           { $$ = $3; }
+    | tELSE InlineStatements                { $$ = $2; }
+
+StatementsBody
+    : /* empty */                                { $$ = NULL; }
+    | StSep StatementsBody                      { $$ = $2; }
+    | SimpleStatement                            { $$ = $1; }
+    | SimpleStatement StSep StatementsBody      { $1->next = $3; $$ = $1; }
+
+InlineStatements_opt
+    : /* empty */                                { $$ = NULL; }
+    | SimpleStatement                            { $$ = $1; }
+    | SimpleStatement StSep StatementsBody      { $1->next = $3; $$ = $1; }
+
+InlineStatements
+    : SimpleStatement                            { $$ = $1; }
+    | SimpleStatement StSep StatementsBody      { $1->next = $3; $$ = $1; }
 
 CaseClausules
     : /* empty */                                                      { $$ = NULL; }
diff --git a/dlls/vbscript/tests/lang.vbs b/dlls/vbscript/tests/lang.vbs
index 12d91a16548..5b4144fca09 100644
--- a/dlls/vbscript/tests/lang.vbs
+++ b/dlls/vbscript/tests/lang.vbs
@@ -359,6 +359,59 @@ ElseIf not False Then
 End If
 Call ok(x, "elseif not called?")
 
+' Else with trailing End If on same line
+x = 1
+If false Then
+   x = 2
+Else x = 3 End If
+Call ok(x = 3, "Else with trailing End If failed")
+
+' Else with colon separator before End If
+x = 1
+If false Then
+   x = 2
+Else x = 3:End If
+Call ok(x = 3, "Else with colon before End If failed")
+
+' Else with colon then statement with trailing End If
+x = 1
+If false Then
+   x = 2
+Else:x = 3 End If
+Call ok(x = 3, "Else colon then statement with trailing End If failed")
+
+' Else with multiple statements and trailing End If
+x = 1
+y = 1
+If false Then
+   x = 2
+Else x = 3:y = 4 End If
+Call ok(x = 3, "Else multi-statement trailing End If failed for x")
+Call ok(y = 4, "Else multi-statement trailing End If failed for y")
+
+' Else with body statement on next line with trailing End If
+x = 1
+If false Then
+   x = 2
+Else
+   x = 3 End If
+Call ok(x = 3, "Else body statement with trailing End If failed")
+
+' ElseIf single-line with trailing End If
+x = 1
+If false Then
+   x = 2
+ElseIf true Then x = 3 End If
+Call ok(x = 3, "ElseIf single-line with trailing End If failed")
+
+' Empty Else block with newline
+x = 1
+If false Then
+   x = 2
+Else
+End If
+Call ok(x = 1, "empty Else block should be accepted")
+
 x = false
 If true Then
   :x = true
diff --git a/dlls/vbscript/tests/run.c b/dlls/vbscript/tests/run.c
index 8aaafbedf54..8cc8a82aa8d 100644
--- a/dlls/vbscript/tests/run.c
+++ b/dlls/vbscript/tests/run.c
@@ -2656,6 +2656,21 @@ static void test_parse_errors(void)
             "    x = 0 End If\n",
             1, 10
         },
+        {
+            /* ElseIf...End If */
+            L"If False Then\n"
+            "    x = 0\n"
+            "ElseIf True Then\n"
+            "    x = 1 End If\n",
+            3, 10
+        },
+        {
+            /* Else End If (no separator) */
+            L"If False Then\n"
+            "    x = 0\n"
+            "Else End If\n",
+            2, 5
+        },
         {
             /* While...End While */
             L"While False\n"
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10333