From 248d73924d6136eee0497a7456aba90bfef633e3 Mon Sep 17 00:00:00 2001
From: Nick Bowler <nbowler@draconx.ca>
Date: Fri, 30 Jun 2023 01:24:12 -0400
Subject: [PATCH] libcdecl: Simplify reduce_parentheses implementation.

Simplify the reduce_parentheses implementation so it operates in a
much more straightforward way.  We can also just call simplify_functions
directly during the same tree traversal, instead of trying to predict
what simplify_functions will do to a node on a later traversal.
---
 src/parse-decl.c | 76 ++++++++++++++++++++++--------------------------
 1 file changed, 34 insertions(+), 42 deletions(-)

diff --git a/src/parse-decl.c b/src/parse-decl.c
index f156ba9..6ab624e 100644
--- a/src/parse-decl.c
+++ b/src/parse-decl.c
@@ -254,58 +254,52 @@ simplify_functions(struct cdecl_declarator **p, struct cdecl_declarator *d)
  * simplify_functions pass.
  */
 
-static int
-reduce_parentheses(struct cdecl_declarator **p, struct cdecl_declarator *d)
+static struct cdecl *fake_function_param(struct cdecl_declarator *d)
 {
 	struct cdecl *param;
 
 	if (d->type != CDECL_DECL_FUNCTION)
-		return 0;
+		return NULL;
 
 	param = d->u.function.parameters;
-	if (param && param->specifiers == NULL) {
-		struct cdecl_declarator *decl;
+	if (!param || param->specifiers)
+		return NULL;
 
-		assert(!param->next);
+	assert(!param->next);
+	return param;
+}
 
-		decl = param->declarators;
-		if (decl->type == CDECL_DECL_NULL) {
-			free(decl);
-			free(param);
-			d->u.function.parameters = NULL;
-			return 0;
-		}
+static int
+reduce_parentheses(struct cdecl_declarator **p, struct cdecl_declarator *d)
+{
+	struct cdecl *param;
+	int fake = 0;
+
+	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;
+			}
 
-		if (d->child->type != CDECL_DECL_NULL) {
-			cdecl__errmsg(CDECL__EBADPARAM);
-			return -1;
+			param->declarators = d;
+			*p = d = decl;
+			fake = 1;
 		}
 
-		free(d->child);
-		free(param);
-		free(d);
-		*p = decl;
-
-		/*
-		 * We may have replaced d with another fake function which
-		 * also needs to be eliminated.
-		 */
-		if (reduce_parentheses(p, decl) < 0)
-			return -1;
-
-		/*
-		 * If the remaining declarator is a function, make sure it's
-		 * valid by checking its reducibility.
-		 */
-		decl = *p;
-		if (decl->type == CDECL_DECL_FUNCTION
-		    && decl->child->type == CDECL_DECL_NULL
-		    && !function_is_reducible(decl)) {
-			cdecl__errmsg(CDECL__EMANYPAREN);
-			return -1;
-		}
+		cdecl__free(param);
+	}
 
-		return 0;
+	simplify_functions(p, d);
+	if (fake && (*p)->type == CDECL_DECL_FUNCTION) {
+		/* Started with a fake function but ended with a real one. */
+		cdecl__errmsg(CDECL__EMANYPAREN);
+		return -1;
 	}
 
 	return 0;
@@ -512,8 +506,6 @@ static int do_postprocess(struct cdecl *decl, int english_mode)
 		if (!english_mode) {
 			if (forall_declarators(i, reduce_parentheses) < 0)
 				return 0;
-			if (forall_declarators(i, simplify_functions) < 0)
-				return 0;
 		}
 
 		if (forall_declarators(i, postproc_common) < 0)
-- 
2.43.2