Clean up parser rules for cpp_members

This simplifies the grammar rules and resolves some corner cases
which currently failed to parse.

This change:

* Simplifies the grammar rules and handles some things in more
  appropriate places

* fixes a parse error for a misplaced Doxygen comment which
  is the only thing in a class/struct.

* fixes a parse error for %include/#include in a class/struct followed
  by a member declaration.

* eliminates an instance of right recursion in the grammar, which the
  bison docs warn against due to O(n) stack use.  See #2884

CHANGES.current

@@ -7,6 +7,14 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.3.0 (in progress)
 ===========================
 
+2024-09-18: olly
+	    Fix parse error for a misplaced Doxygen comment which is the only
+	    thing in a class/struct.
+
+2024-09-18: olly
+	    Fix parse error for %include/#include in a class/struct followed
+	    by a member declaration.
+
 2024-09-16: olly
 	    #2995 SWIG now has generic handling for converting integer and
 	    boolean literal values for use in target language code, replacing

Examples/test-suite/doxygen_misc_constructs.i

@@ -183,6 +183,11 @@
       int bbbb; //! not for bbbb value, is quietly ignored by Doxygen and SWIG
     };
 
+    struct OrphanedComment
+    {
+      /** Doxygen quietly ignores this; SWIG < 4.3.0 gave parse error. */
+    };
+
     #include "doxygen_misc_constructs.h"
 
 %}

Examples/test-suite/inctest.i

@@ -33,3 +33,16 @@ typedef struct {
 typedef struct {
 %include "inctest.h"
 } MY_THINGS;
+
+// Regression test: we failed to handle the case of a member after the include.
+%{
+struct MY_THINGS2 {
+#include "inctest2.h"
+int failed_before_swig_430;
+};
+%}
+
+struct MY_THINGS2 {
+%include "inctest2.h"
+int failed_before_swig_430;
+};

Examples/test-suite/inctest2.h

@@ -0,0 +1 @@
+int IntegerMember;

Source/CParse/parser.y

@@ -1753,6 +1753,10 @@ static String *add_qualifier_to_declarator(SwigType *type, SwigType *qualifier)
     Parm       *parms;
     Parm       *last;
   } pbuilder;
+  struct {
+    Node       *node;
+    Node       *last;
+  } nodebuilder;
 };
 
 /* Define special token END for end of input. */
@@ -1832,6 +1836,7 @@ static String *add_qualifier_to_declarator(SwigType *type, SwigType *qualifier)
 /* C++ declarations */
 %type <node>     cpp_declaration cpp_class_decl cpp_forward_class_decl cpp_template_decl;
 %type <node>     cpp_members cpp_member cpp_member_no_dox;
+%type <nodebuilder> cpp_members_builder;
 %type <node>     cpp_constructor_decl cpp_destructor_decl cpp_protection_decl cpp_conversion_operator cpp_static_assert;
 %type <node>     cpp_swig_directive cpp_template_possible cpp_opt_declarators ;
 %type <node>     cpp_using_decl cpp_namespace_decl cpp_catch_decl cpp_lambda_decl;
@@ -4841,44 +4846,52 @@ Printf(stdout, "  Scope %s [creating single scope C++17 style]\n", scopename);
              }
              ;
 
-cpp_members  : cpp_member cpp_members[in] {
+cpp_members : cpp_members_builder {
-                   $$ = $cpp_member;
+		 $$ = $cpp_members_builder.node;
-                   /* Insert cpp_member (including any siblings) to the front of the cpp_members linked list */
-		   if ($$) {
-		     Node *p = $$;
-		     Node *pp =0;
-		     while (p) {
-		       pp = p;
-		       p = nextSibling(p);
-		     }
-		     set_nextSibling(pp,$in);
-		     if ($in)
-		       set_previousSibling($in, pp);
-		   } else {
-		     $$ = $in;
-		   }
-	     }
-	     | cpp_member DOXYGENSTRING /* Misplaced doxygen string after a member, quietly ignore, like Doxygen does */
-             | EXTEND LBRACE { 
-	       extendmode = 1;
-	       if (cplus_mode != CPLUS_PUBLIC) {
-		 Swig_error(cparse_file,cparse_line,"%%extend can only be used in a public section\n");
 	       }
-             } cpp_members[extend_members] RBRACE {
+	       | cpp_members_builder DOXYGENSTRING {
-	       extendmode = 0;
+		 /* Quietly ignore misplaced doxygen string after a member, like Doxygen does */
-	     } cpp_members[in] {
+		 $$ = $cpp_members_builder.node;
-	       $$ = new_node("extend");
+	       }
-	       mark_nodes_as_extend($extend_members);
+	       | %empty {
-	       appendChild($$,$extend_members);
+		 $$ = 0;
-	       set_nextSibling($$,$in);
+	       }
+	       | DOXYGENSTRING {
+		 /* Quietly ignore misplaced doxygen string in empty class, like Doxygen does */
+		 $$ = 0;
+	       }
+	       | error {
+		 Swig_error(cparse_file, cparse_line, "Syntax error in input(3).\n");
+		 Exit(EXIT_FAILURE);
+	       }
+	       ;
+
+cpp_members_builder : cpp_member {
+	     $$.node = $$.last = $cpp_member;
+	   }
+	   | cpp_members_builder[in] cpp_member {
+	     // Build a linked list in the order specified, but avoiding
+	     // a right recursion rule because "Right recursion uses up
+	     // space on the Bison stack in proportion to the number of
+	     // elements in the sequence".
+	     if ($cpp_member) {
+	       if ($in.node) {
+		 Node *last = $in.last;
+		 /* Advance to the last sibling. */
+		 for (Node *p = last; p; p = nextSibling(p)) {
+		   last = p;
+		 }
+		 set_nextSibling(last, $cpp_member);
+		 set_previousSibling($cpp_member, last);
+		 $$.node = $in.node;
+	       } else {
+		 $$.node = $$.last = $cpp_member;
+	       }
+	     } else {
+	       $$ = $in;
 	     }
-             | include_directive
+	   }
-             | %empty { $$ = 0;}
+	   ;
-	     | error {
-	       Swig_error(cparse_file,cparse_line,"Syntax error in input(3).\n");
-	       Exit(EXIT_FAILURE);
-	     }
-             ;
 
 /* ======================================================================
  *                         C++ Class members
@@ -4914,6 +4927,7 @@ cpp_member_no_dox : c_declaration
              | cpp_using_decl
              | cpp_template_decl
              | cpp_catch_decl
+	     | include_directive
              | template_directive
              | warn_directive
              | anonymous_bitfield { $$ = 0; }
@@ -4930,6 +4944,17 @@ cpp_member   : cpp_member_no_dox
 	         $$ = $cpp_member_no_dox;
 		 set_comment($cpp_member_no_dox, $DOXYGENPOSTSTRING);
 	     }
+	     | EXTEND LBRACE {
+	       extendmode = 1;
+	       if (cplus_mode != CPLUS_PUBLIC) {
+		 Swig_error(cparse_file,cparse_line,"%%extend can only be used in a public section\n");
+	       }
+	     } cpp_members RBRACE {
+	       extendmode = 0;
+	       $$ = new_node("extend");
+	       mark_nodes_as_extend($cpp_members);
+	       appendChild($$, $cpp_members);
+	     }
              ;
 
 /* Possibly a constructor */