X-Git-Url: https://git.draconx.ca/gitweb/cdecl99.git/blobdiff_plain/96b00735351dd8e39fc5d71ff31afbdddd83ecba..0c3d696d84c1d76482d83e76e4c2b4218b028f1f:/src/parse-decl.c

diff --git a/src/parse-decl.c b/src/parse-decl.c
index a31a377..3c60dd2 100644
--- a/src/parse-decl.c
+++ b/src/parse-decl.c
@@ -1,6 +1,6 @@
 /*
  * Parse and validate C declarations.
- * Copyright © 2011-2012, 2020-2021, 2023 Nick Bowler
+ * Copyright © 2011-2012, 2020-2021, 2023-2024 Nick Bowler
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -27,6 +27,8 @@
 #include "scan.h"
 #include "errmsg.h"
 
+static struct cdecl *fake_function_param(struct cdecl_declarator *);
+
 /*
  * Allocate a "parse item", which is a union of several parse tree
  * structure types, together with a string buffer.  The s_sz argument
@@ -73,9 +75,10 @@ struct parse_item *cdecl__alloc_item(size_t s_sz)
  */
 static int valid_typespec(struct cdecl_declspec *s)
 {
+	struct cdecl_declspec *c;
 	unsigned long map = 0;
 
-	for (struct cdecl_declspec *c = s; c; c = c->next) {
+	for (c = s; c; c = c->next) {
 		unsigned long bit;
 
 		if (cdecl_spec_kind(c) != CDECL_SPEC_TYPE)
@@ -117,7 +120,7 @@ static int valid_typespec(struct cdecl_declspec *s)
  */
 static bool valid_declspecs(struct cdecl *decl, bool top)
 {
-	struct cdecl_declspec *specs = decl->specifiers;
+	struct cdecl_declspec *c, *specs = decl->specifiers;
 	struct cdecl_declarator *d   = decl->declarators;
 	bool abstract = cdecl_is_abstract(d);
 	unsigned num_storage = 0;
@@ -125,7 +128,7 @@ static bool valid_declspecs(struct cdecl *decl, bool top)
 	if (!valid_typespec(specs))
 		return false;
 
-	for (struct cdecl_declspec *c = specs; c; c = c->next) {
+	for (c = specs; c; c = c->next) {
 		switch (cdecl_spec_kind(c)) {
 		case CDECL_SPEC_TYPE:
 			if (c->type == CDECL_TYPE_VOID &&
@@ -176,6 +179,36 @@ static bool valid_declspecs(struct cdecl *decl, bool top)
 	return true;
 }
 
+/*
+ * Find the tree pointer which leads to the parameter's leaf node.
+ *
+ * Return a null pointer if the traversal locates a syntactic element which
+ * prevents function reduction.  This occurs if the leaf node declares an
+ * identifier, or for nontrivial fake function parameters (see below).
+ */
+static struct cdecl_declarator **leaf_pointer(struct cdecl *param)
+{
+	struct cdecl_declarator *d, **p = &param->declarators;
+
+	if ((param = fake_function_param(param->declarators))) {
+		if (param->declarators->type != CDECL_DECL_NULL)
+			return NULL; /* e.g. int (x (*)) */
+	}
+
+	while ((d = *p)->child) {
+		p = &d->child;
+
+		if (fake_function_param(d->child))
+			return NULL; /* e.g. int (x (*)[][1]) */
+	}
+
+	if (d->type != CDECL_DECL_NULL)
+		return NULL; /* e.g. int (x y) */
+
+	return p;
+}
+
+
 /*
  * The C grammar leaves ambiguous some cases where parentheses represent a
  * function declarator or just parentheses.  The language uses additional
@@ -200,13 +233,10 @@ static bool valid_declspecs(struct cdecl *decl, bool top)
 
 static struct cdecl_declarator *reduce_function(struct cdecl *param)
 {
-	struct cdecl_declarator *d, **p = &param->declarators;
 	struct parse_item *spec = (void *)param->specifiers;
+	struct cdecl_declarator *d, **p;
 
-	while ((d = *p)->child)
-		p = &d->child;
-
-	if (d->type != CDECL_DECL_NULL)
+	if (!(p = leaf_pointer(param)))
 		return NULL;
 
 	/*
@@ -259,7 +289,7 @@ simplify_functions(struct cdecl_declarator **p, struct cdecl_declarator *d)
 
 	new = reduce_function(d->u.function.parameters);
 	if (!new)
-		return 0; /* e.g. int (foo bar) */
+		return 0;
 	*p = new;
 	free(d);
 
@@ -500,9 +530,9 @@ static int forall_declarators(struct cdecl *decl,
 
 static struct cdecl *do_parse(const char *str, int english_mode)
 {
+	struct cdecl *decl = NULL;
 	YY_BUFFER_STATE state;
 	yyscan_t scanner;
-	struct cdecl *decl;
 
 #if YYDEBUG
 	extern int cdecl__yydebug;
@@ -514,8 +544,15 @@ static struct cdecl *do_parse(const char *str, int english_mode)
 		return NULL;
 
 	state = cdecl__yy_scan_string(str, scanner);
-	if (cdecl__yyparse(scanner, &decl) != 0)
+	if (cdecl__yyparse(scanner, &decl) != 0) {
+		/*
+		 * If the input consists of a complete, valid declaration
+		 * followed by some garbage, that parsed declaration will
+		 * be output by the parser and we need to free it here.
+		 */
+		cdecl__free(decl);
 		decl = NULL;
+	}
 	cdecl__yy_delete_buffer(state, scanner);
 	cdecl__yylex_destroy(scanner);