Fix syntax error parsing an expression

which calls a function with no parameters within additional brackets.

This is more of a hack than a fix as attempts to parse properly
failed, see issue #2640.

Closes #2640

CHANGES.current

@@ -7,9 +7,13 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.2.0 (in progress)
 ===========================
 
+2023-06-30: wsfulton
+            #2640 Fix syntax error parsing an expression which calls a function
+            with no parameters within additional brackets.
+
 2023-06-27: mmomtchev
-      [Javascript] #2545 New Javascript generator targeting the Node.js
-      binary stable ABI Node-API.
+            [Javascript] #2545 New Javascript generator targeting the Node.js
+            binary stable ABI Node-API.
 
 2023-06-27: olly
 	    [Java] Completely remove pragmas which were deprecated in 2002 and

Examples/test-suite/common.mk

@@ -592,6 +592,7 @@ CPP11_TEST_CASES += \
 	cpp11_alternate_function_syntax \
 	cpp11_attribute_specifiers \
 	cpp11_auto_variable \
+	cpp11_brackets_expression \
 	cpp11_constexpr \
 	cpp11_decltype \
 	cpp11_default_delete \

Examples/test-suite/cpp11_brackets_expression.i

@@ -0,0 +1,35 @@
+%module cpp11_brackets_expression
+
+%warnfilter(SWIGWARN_PARSE_ASSIGNED_VALUE) Piece::kMaxSize;
+%warnfilter(SWIGWARN_PARSE_ASSIGNED_VALUE) Piece::Just123;
+%warnfilter(SWIGWARN_PARSE_ASSIGNED_VALUE) ::kMaxSizeGlobal;
+
+%inline %{
+
+#include <limits>
+
+static constexpr int global_as_you_expect(int val) { return val; }
+static constexpr int global_one_two_three() { return 123; }
+
+class Piece {
+public:
+    typedef size_t size_type;
+    typedef int difference_type;
+
+    static constexpr size_type kOk2 = std::numeric_limits<difference_type>::max();
+
+    // Failed to parse (issue #2640):
+    static constexpr size_type kMaxSize = (std::numeric_limits<difference_type>::max)();
+
+    // Also fails to parse:
+//    int f(int x = (std::numeric_limits<difference_type>::max)());
+
+    static constexpr size_type SimpleAsYouExpect123 = global_as_you_expect(123);
+    static constexpr size_type SimpleJust123 = global_one_two_three();
+
+    static constexpr size_type AsYouExpect123 = (global_as_you_expect)(123); // Did parse okay
+    static constexpr size_type Just123 = (global_one_two_three)();           // Did not parse okay
+};
+
+static const Piece::size_type kMaxSizeGlobal = (std::numeric_limits<Piece::difference_type>::max)();
+%}

Examples/test-suite/java/cpp11_brackets_expression_runme.java

@@ -0,0 +1,24 @@
+import cpp11_brackets_expression.*;
+
+public class cpp11_brackets_expression_runme {
+
+  static {
+    try {
+	System.loadLibrary("cpp11_brackets_expression");
+    } catch (UnsatisfiedLinkError e) {
+      System.err.println("Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.\n" + e);
+      System.exit(1);
+    }
+  }
+
+  public static void main(String argv[]) {
+    long x = Piece.kMaxSize;
+    x = Piece.SimpleAsYouExpect123;
+    x = Piece.Just123;
+    x = cpp11_brackets_expression.getKMaxSizeGlobal();
+
+    x = cpp11_brackets_expression.getKMaxSizeGlobal();
+    x = cpp11_brackets_expression.global_as_you_expect(123);
+    x = cpp11_brackets_expression.global_one_two_three();
+  }
+}

Source/CParse/parser.y

@@ -581,6 +581,13 @@ static void add_symbols(Node *n) {
       n = nextSibling(n);
       continue;
     }
+
+    if (GetFlag(n, "valueignored")) {
+      SWIG_WARN_NODE_BEGIN(n);
+      Swig_warning(WARN_PARSE_ASSIGNED_VALUE, Getfile(n), Getline(n), "Value assigned to %s not used due to limited parsing implementation.\n", SwigType_namestr(Getattr(n, "name")));
+      SWIG_WARN_NODE_END(n);
+    }
+
     if (cparse_cplusplus) {
       String *value = Getattr(n, "value");
       if (value && Strcmp(value, "delete") == 0) {
@@ -3233,8 +3240,47 @@ c_decl  : storage_class type declarator cpp_const initializer c_decl_tail {
 		Swig_error(cparse_file, cparse_line, "Static function %s cannot have a qualifier.\n", Swig_name_decl($$));
            }
 	   | storage_class type declarator cpp_const EQUAL error SEMI {
-	      Swig_warning(999, cparse_file, cparse_line, "Ignoring declaration of '%s' due to parser limitation.\n", $3.id);
-	      $$ = 0;
+	      String *decl = $3.type;
+	      $$ = new_node("cdecl");
+	      if ($4.qualifier)
+	        decl = add_qualifier_to_declarator($3.type, $4.qualifier);
+	      Setattr($$, "refqualifier", $4.refqualifier);
+	      Setattr($$, "type", $2);
+	      Setattr($$, "storage", $1);
+	      Setattr($$, "name", $3.id);
+	      Setattr($$, "decl", decl);
+	      Setattr($$, "parms", $3.parms);
+
+	      /* Set dummy value to avoid adding in code for handling missing value in later stages */
+	      Setattr($$, "value", "*parse error*");
+	      SetFlag($$, "valueignored");
+
+	      Setattr($$, "throws", $4.throws);
+	      Setattr($$, "throw", $4.throwf);
+	      Setattr($$, "noexcept", $4.nexcept);
+	      Setattr($$, "final", $4.final);
+
+	      if (Strstr($3.id, "::")) {
+		String *p = Swig_scopename_prefix($3.id);
+		if (p) {
+		  if ((Namespaceprefix && Strcmp(p, Namespaceprefix) == 0) ||
+		      (Classprefix && Strcmp(p, Classprefix) == 0)) {
+		    String *lstr = Swig_scopename_last($3.id);
+		    Setattr($$, "name", lstr);
+		    Delete(lstr);
+		  } else {
+		    Delete($$);
+		    $$ = 0;
+		  }
+		  Delete(p);
+		} else {
+		  Delete($$);
+		  $$ = 0;
+		}
+	      }
+
+	      if ($4.qualifier && $1 && Strstr($1, "static"))
+		Swig_error(cparse_file, cparse_line, "Static function %s cannot have a qualifier.\n", Swig_name_decl($$));
 	   }
            /* Alternate function syntax introduced in C++11:
               auto funcName(int x, int y) -> int; */

Source/Include/swigwarn.h

@@ -94,6 +94,7 @@
 #define WARN_PARSE_NAMED_NESTED_CLASS 325
 #define WARN_PARSE_EXTEND_NAME        326
 #define WARN_PARSE_EXTERN_TEMPLATE    327
+#define WARN_PARSE_ASSIGNED_VALUE     328
 
 #define WARN_CPP11_LAMBDA             340
 #define WARN_CPP11_ALIAS_DECLARATION  341  /* redundant now */