From: Nick Bowler <nbowler@draconx.ca>
Date: Thu, 6 Jul 2023 06:15:35 +0000 (-0400)
Subject: libcdecl: Fix regression in function parsing.
X-Git-Tag: v1.3~129
X-Git-Url: https://git.draconx.ca/gitweb/cdecl99.git/commitdiff_plain/bcde46a8503359755ca72fe581a18f7a3bcaaf37

libcdecl: Fix regression in function parsing.

Merging the reduce_parentheses and simplify_functions step missed a case
where the function simplification could pull a fake function declarator
up to the current tree position.  Continuing the tree traversal will miss
this, leaving the fake parameter in the tree (which is then rejected as
a syntax error later).

The fix is easy enough, just repeat the whole reduction step until no
changes are needed at the current position before continuing traversal.

Add a new test case that targets this behaviour.
---

diff --git a/src/parse-decl.c b/src/parse-decl.c
index c3ba32d..a6204a1 100644
--- a/src/parse-decl.c
+++ b/src/parse-decl.c
@@ -230,7 +230,7 @@ simplify_functions(struct cdecl_declarator **p, struct cdecl_declarator *d)
 	free(d->child);
 	free(d);
 
-	return 0;
+	return 1;
 }
 
 /*
@@ -260,6 +260,9 @@ simplify_functions(struct cdecl_declarator **p, struct cdecl_declarator *d)
  * example, "(((x)))" into "(x)", an abstract function declarator.  The result
  * is then subject to the function simplification step, which will turn "(x)"
  * into x (declaring an identifier).
+ *
+ * The whole process is repeated until no more changes are made to the parse
+ * tree, or a syntax error is detected.
  */
 static struct cdecl *fake_function_param(struct cdecl_declarator *d)
 {
@@ -281,26 +284,28 @@ reduce_parentheses(struct cdecl_declarator **p, struct cdecl_declarator *d)
 {
 	struct cdecl *param;
 
-	while ((param = fake_function_param(d))) {
-		struct cdecl_declarator *decl = param->declarators;
-		d->u.function.parameters = NULL;
-
-		if (decl->type != CDECL_DECL_NULL) {
-			if (d->child->type != CDECL_DECL_NULL) {
-				/* Found fake parameter on real function. */
-				d->u.function.parameters = param;
-				cdecl__errmsg(CDECL__EBADPARAM);
-				return -1;
+	do {
+		d = *p;
+		while ((param = fake_function_param(d))) {
+			struct cdecl_declarator *decl = param->declarators;
+			d->u.function.parameters = NULL;
+
+			if (decl->type != CDECL_DECL_NULL) {
+				if (d->child->type != CDECL_DECL_NULL) {
+					/* Fake parameter on real function. */
+					d->u.function.parameters = param;
+					cdecl__errmsg(CDECL__EBADPARAM);
+					return -1;
+				}
+
+				param->declarators = d;
+				*p = d = decl;
 			}
 
-			param->declarators = d;
-			*p = d = decl;
+			cdecl__free(param);
 		}
+	} while (simplify_functions(p, d));
 
-		cdecl__free(param);
-	}
-
-	simplify_functions(p, d);
 	return 0;
 }
 
diff --git a/tests/decl-good.at b/tests/decl-good.at
index 7cd68db..230202b 100644
--- a/tests/decl-good.at
+++ b/tests/decl-good.at
@@ -100,3 +100,7 @@ SIMPLE_DECLS_EXPLAIN(
   [[int ((int))], [type function (int) returning int], [int (int)]],
   [[int (x(int))], [declare x as function (int) returning int], [int x(int)]],
   [[int (())], [type function returning int], [int ()]])
+
+SIMPLE_DECLS_EXPLAIN(
+  [[int (x())], [declare x as function returning int], [int x()]],
+  [[int ((x)())], [declare x as function returning int], [int x()]])