Improve parsing of expressions related to functions calls

For example, the following no longer give parse errors:  `g().d()`,
`g().D`, `(f(1) < g(2))`, `sizeof f(a,b)`

Partly addresses #3197

CHANGES.current

@@ -7,6 +7,11 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.4.0 (in progress)
 ===========================
 
+2025-06-17: olly
+	    #3197 Improve parsing of expressions related to functions calls.
+	    For example, the following no longer give parse errors:  `g().d()`,
+	    `g().D`, `(f(1) < g(2))`, `sizeof f(a,b)`
+
 2025-06-11: wsfulton
             [Python] Add support for -builtin and heap types turned on with
             -DSWIG_HEAPTYPES. This is an important step towards supporting a number of
@@ -42,6 +47,7 @@ Version 4.4.0 (in progress)
 	    with Tcl 8.x.  Regression introduced in SWIG 4.2.1.  As a bonus
 	    the generated header no longer requires the user to include tcl.h
 	    and various standard C library headers before including it.
+
 2025-05-28: olly
 	    #3186 Fix parse error for C++14 forward declaration of function with
 	    auto return type and no trailing return type.

Examples/test-suite/constant_expr_c.i

@@ -75,6 +75,10 @@ const int s8a = sizeof(2.1e-6);
 const int s8b = sizeof 2.1e-6;
 const int s9a = sizeof(-s8a);
 // const int s9b = sizeof -s8a; /* not currently supported */
+const int s10a = sizeof(xx());
+// Before 4.4.0 this gave:
+// Warning 328: Value assigned to s10b not used due to limited parsing implementation.
+const int s10b = sizeof xx();
 
 %}
 

Examples/test-suite/default_arg_expressions.i

@@ -8,6 +8,9 @@
 %warnfilter(SWIGWARN_TYPEMAP_SWIGTYPELEAK) UsdGeomTokensPtr;
 %immutable UsdGeomTokens;
 
+// helper() only exists to test we can parse more complex expressions.
+%ignore helper;
+
 // Don't call our getters get_xxx() as that collides with generated getters in
 // some languages (e.g. csharp).
 
@@ -70,4 +73,11 @@ void CreateMaterialBindSubsetw(int num = UsdGeomTokensPtr->g_face().g_val().g_va
 void CreateMaterialBindSubsetx(int num = UsdGeomTokens.g_face().g_val().g_val()) {}
 void CreateMaterialBindSubsety(int num = UsdGeomTokens.g_face(1).g_val().g_val()) {}
 void CreateMaterialBindSubsetz(int num = UsdGeomTokens.g_face(1,2).g_val().g_val()) {}
+
+// Regression tests for #3197.
+Tokens& helper(bool = false, bool = false) { return UsdGeomTokens; }
+void ParseTest1(int num = helper().face.val.val) {}
+void ParseTest2(int num = helper().g_face().val.val) {}
+void ParseTestN(bool b = (helper().g_face().val.val < helper().face.val.val)) {}
+
 %}

Examples/test-suite/php/constant_expr_c_runme.php

@@ -7,7 +7,7 @@ check::functions(array('xx', 'yy'));
 // New classes
 check::classes(array('constant_expr_c'));
 // New vars
-check::globals(array('X','d_array','s1a','s2a','s2b','s3a','s3b','s4a','s4b','s5a','s5b','s6a','s6b','s7a','s7b','s8a','s8b','s9a'));
+check::globals(array('X','d_array','s1a','s2a','s2b','s3a','s3b','s4a','s4b','s5a','s5b','s6a','s6b','s7a','s7b','s8a','s8b','s9a', 's10a', 's10b'));
 
 check::equal(XX, xx());
 check::equal(YY, yy());

Examples/test-suite/php/constant_expr_runme.php

@@ -7,7 +7,7 @@ check::functions(array('bar', 'test2', 'xx', 'yy'));
 // New classes
 check::classes(array('constant_expr'));
 // New vars
-check::globals(array('X','a','d_array','s1a','s2a','s2b','s3a','s3b','s4a','s4b','s5a','s5b','s6a','s6b','s7a','s7b','s8a','s8b', 's9a'));
+check::globals(array('X','a','d_array','s1a','s2a','s2b','s3a','s3b','s4a','s4b','s5a','s5b','s6a','s6b','s7a','s7b','s8a','s8b', 's9a', 's10a', 's10b'));
 
 check::equal(XX, xx());
 check::equal(YY, yy());

Source/CParse/parser.y

@@ -6759,7 +6759,7 @@ expr           : valexpr
                }
 	       ;
 
-/* simple member access expressions */
+/* member access expressions and function calls */
 exprmem        : ID[lhs] ARROW ID[rhs] {
 		 $$ = default_dtype;
 		 $$.val = NewStringf("%s->%s", $lhs, $rhs);
@@ -6781,6 +6781,31 @@ exprmem        : ID[lhs] ARROW ID[rhs] {
 		 $$ = $in;
 		 append_expr_from_scanner($$.val);
 	       }
+	       | type LPAREN {
+		 $$ = default_dtype;
+		 if (skip_balanced('(', ')') < 0) Exit(EXIT_FAILURE);
+
+		 String *qty = Swig_symbol_type_qualify($type, 0);
+		 if (SwigType_istemplate(qty)) {
+		   String *nstr = SwigType_namestr(qty);
+		   Delete(qty);
+		   qty = nstr;
+		 }
+		 /* Try to deduce the type - this could be a C++ "constructor
+		  * cast" such as `double(4)` or a function call such as
+		  * `some_func()`.  In the latter case we get T_USER, but that
+		  * is wrong so we map it to T_UNKNOWN until we can actually
+		  * deduce the return type of a function call (which is
+		  * complicated because the return type can vary between
+		  * overloaded forms).
+		  */
+		 $$.type = SwigType_type(qty);
+		 if ($$.type == T_USER) $$.type = T_UNKNOWN;
+		 $$.unary_arg_type = 0;
+
+		 $$.val = qty;
+		 append_expr_from_scanner($$.val);
+	       }
 	       ;
 
 /* Non-compound expression */
@@ -7298,31 +7323,6 @@ exprcompound   : expr[lhs] PLUS expr[rhs] {
                  $$.val = NewStringf("!%s", $in.val);
 		 $$.type = cparse_cplusplus ? T_BOOL : T_INT;
 	       }
-               | type LPAREN {
-		 $$ = default_dtype;
-		 if (skip_balanced('(',')') < 0) Exit(EXIT_FAILURE);
-
-		 String *qty = Swig_symbol_type_qualify($type, 0);
-		 if (SwigType_istemplate(qty)) {
-		   String *nstr = SwigType_namestr(qty);
-		   Delete(qty);
-		   qty = nstr;
-		 }
-		 /* Try to deduce the type - this could be a C++ "constructor
-		  * cast" such as `double(4)` or a function call such as
-		  * `some_func()`.  In the latter case we get T_USER, but that
-		  * is wrong so we map it to T_UNKNOWN until we can actually
-		  * deduce the return type of a function call (which is
-		  * complicated because the return type can vary between
-		  * overloaded forms).
-		  */
-		 $$.type = SwigType_type(qty);
-		 if ($$.type == T_USER) $$.type = T_UNKNOWN;
-		 $$.unary_arg_type = 0;
-
-		 $$.val = qty;
-		 append_expr_from_scanner($$.val);
-               }
                ;
 
 variadic_opt  : ELLIPSIS {