v.gen.c: allow overriding of the == operator on C.Struct type aliases

vlib/v/gen/c/auto_eq_methods.v

@@ -58,24 +58,25 @@ fn (mut g Gen) gen_sumtype_equality_fn(left_type ast.Type) string {
 fn (mut g Gen) gen_struct_equality_fn(left_type ast.Type) string {
 	left := g.unwrap(left_type)
 	ptr_styp := g.typ(left.typ.set_nr_muls(0))
-	if ptr_styp in g.struct_fn_definitions {
-		return ptr_styp
+	fn_name := ptr_styp.replace('struct ', '')
+	if fn_name in g.struct_fn_definitions {
+		return fn_name
 	}
-	g.struct_fn_definitions << ptr_styp
+	g.struct_fn_definitions << fn_name
 	info := left.sym.struct_info()
-	g.type_definitions.writeln('static bool ${ptr_styp}_struct_eq($ptr_styp a, $ptr_styp b); // auto')
+	g.type_definitions.writeln('static bool ${fn_name}_struct_eq($ptr_styp a, $ptr_styp b); // auto')
 
 	mut fn_builder := strings.new_builder(512)
 	defer {
 		g.auto_fn_definitions << fn_builder.str()
 	}
-	fn_builder.writeln('static bool ${ptr_styp}_struct_eq($ptr_styp a, $ptr_styp b) {')
+	fn_builder.writeln('static bool ${fn_name}_struct_eq($ptr_styp a, $ptr_styp b) {')
 
 	// overloaded
 	if left.sym.has_method('==') {
-		fn_builder.writeln('\treturn ${ptr_styp}__eq(a, b);')
+		fn_builder.writeln('\treturn ${fn_name}__eq(a, b);')
 		fn_builder.writeln('}')
-		return ptr_styp
+		return fn_name
 	}
 
 	fn_builder.write_string('\treturn ')
@@ -117,7 +118,7 @@ fn (mut g Gen) gen_struct_equality_fn(left_type ast.Type) string {
 	}
 	fn_builder.writeln(';')
 	fn_builder.writeln('}')
-	return ptr_styp
+	return fn_name
 }
 
 fn (mut g Gen) gen_alias_equality_fn(left_type ast.Type) string {

vlib/v/gen/c/infix_expr.v

@@ -81,10 +81,11 @@ fn (mut g Gen) infix_expr_arrow_op(node ast.InfixExpr) {
 fn (mut g Gen) infix_expr_eq_op(node ast.InfixExpr) {
 	left := g.unwrap(node.left_type)
 	right := g.unwrap(node.right_type)
-	has_operator_overloading := g.table.type_has_method(left.sym, '==')
+	has_defined_eq_operator := g.table.type_has_method(left.sym, '==')
+	has_alias_eq_op_overload := left.sym.info is ast.Alias && left.sym.has_method('==')
 	if (left.typ.is_ptr() && right.typ.is_int()) || (right.typ.is_ptr() && left.typ.is_int()) {
 		g.gen_plain_infix_expr(node)
-	} else if (left.typ.idx() == ast.string_type_idx || (!has_operator_overloading
+	} else if (left.typ.idx() == ast.string_type_idx || (!has_defined_eq_operator
 		&& left.unaliased.idx() == ast.string_type_idx)) && node.right is ast.StringLiteral
 		&& (node.right as ast.StringLiteral).val == '' {
 		// `str == ''` -> `str.len == 0` optimization
@@ -93,11 +94,15 @@ fn (mut g Gen) infix_expr_eq_op(node ast.InfixExpr) {
 		g.write(')')
 		arrow := if left.typ.is_ptr() { '->' } else { '.' }
 		g.write('${arrow}len $node.op 0')
-	} else if has_operator_overloading {
+	} else if has_defined_eq_operator {
 		if node.op == .ne {
 			g.write('!')
 		}
+		if has_alias_eq_op_overload {
+			g.write(g.typ(left.typ.set_nr_muls(0)))
+		} else {
 			g.write(g.typ(left.unaliased.set_nr_muls(0)))
+		}
 		g.write('__eq(')
 		g.write('*'.repeat(left.typ.nr_muls()))
 		g.expr(node.left)

vlib/v/tests/aliasing_c_structs/cstructs.h

@@ -0,0 +1,8 @@
+
+struct __mpz_struct1 {
+   int x;   
+};
+
+typedef struct __mpz_struct2 {
+   int x;   
+} __mpz_struct_typedef;

vlib/v/tests/aliasing_c_structs/eq_operator_overload_of_c_struct_alias_test.v

@@ -0,0 +1,58 @@
+#include "@VMODROOT/cstructs.h"
+
+struct C.__mpz_struct1 {
+	x int
+}
+
+[typedef]
+struct C.__mpz_struct_typedef {
+	x int
+}
+
+type Bigint = C.__mpz_struct1
+type BigintTypedef = C.__mpz_struct_typedef
+
+pub fn (a Bigint) == (b Bigint) bool {
+	println('>>>>         struct a.x: $a.x | == | b.x: $b.x  => ${a.x == b.x:-5} <<<<')
+	return a.x == b.x
+}
+
+pub fn (a BigintTypedef) == (b BigintTypedef) bool {
+	println('>>>> typedef struct a.x: $a.x | == | b.x: $b.x  => ${a.x == b.x:-5} <<<<')
+	return a.x == b.x
+}
+
+fn test_ordinary_c_struct_aliases_with_an_equal_op_overload() {
+	bi_1 := Bigint{
+		x: 12
+	}
+	bi_2 := Bigint{
+		x: 34
+	}
+	bi_3 := Bigint{
+		x: 12
+	}
+	println(bi_1)
+	println(bi_2)
+	assert bi_1 == bi_1
+	assert bi_1 == bi_3
+	assert bi_1 != bi_2
+}
+
+fn test_typedefed_c_struct_aliases_with_an_equal_op_overload() {
+	bit_1 := BigintTypedef{
+		x: 55
+	}
+	bit_2 := BigintTypedef{
+		x: 99
+	}
+	bit_3 := BigintTypedef{
+		x: 55
+	}
+	println(bit_1)
+	println(bit_2)
+	println(bit_3)
+	assert bit_1 == bit_1
+	assert bit_1 == bit_3
+	assert bit_1 != bit_2
+}