cgen: fix clash in generated variant and method names (#10581)

vlib/v/gen/c/auto_str_methods.v

@@ -326,7 +326,7 @@ fn (mut g Gen) gen_str_for_enum(info ast.Enum, styp string, str_fn_name string)
 			} else if info.is_multi_allowed {
 				seen << val
 			}
-			g.auto_str_funcs.writeln('\t\tcase ${s}_$val: return _SLIT("$val");')
+			g.auto_str_funcs.writeln('\t\tcase ${s}__$val: return _SLIT("$val");')
 		}
 		g.auto_str_funcs.writeln('\t\tdefault: return _SLIT("unknown enum value");')
 		g.auto_str_funcs.writeln('\t}')

vlib/v/gen/c/cgen.v

@@ -1201,7 +1201,7 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 			mut cur_enum_expr := ''
 			mut cur_enum_offset := 0
 			for i, field in node.fields {
-				g.enum_typedefs.write_string('\t${enum_name}_$field.name')
+				g.enum_typedefs.write_string('\t${enum_name}__$field.name')
 				if field.has_expr {
 					g.enum_typedefs.write_string(' = ')
 					expr_str := g.expr_string(field.expr)
@@ -3176,7 +3176,7 @@ fn (mut g Gen) expr(node ast.Expr) {
 			// g.write('${it.mod}${it.enum_name}_$it.val')
 			// g.enum_expr(node)
 			styp := g.typ(node.typ)
-			g.write('${styp}_$node.val')
+			g.write('${styp}__$node.val')
 		}
 		ast.FloatLiteral {
 			g.write(node.val)
@@ -4071,9 +4071,9 @@ fn (mut g Gen) select_expr(node ast.SelectExpr) {
 			g.write(', ')
 		}
 		if is_push[i] {
-			g.write('sync__Direction_push')
+			g.write('sync__Direction__push')
 		} else {
-			g.write('sync__Direction_pop')
+			g.write('sync__Direction__pop')
 		}
 	}
 	g.writeln('}));\n')

vlib/v/gen/c/comptime.v

@@ -519,7 +519,7 @@ fn (mut g Gen) comp_for(node ast.CompFor) {
 				g.writeln('\t${node.val_var}.name = _SLIT("$attr.name");')
 				g.writeln('\t${node.val_var}.has_arg = $attr.has_arg;')
 				g.writeln('\t${node.val_var}.arg = _SLIT("$attr.arg");')
-				g.writeln('\t${node.val_var}.kind = AttributeKind_$attr.kind;')
+				g.writeln('\t${node.val_var}.kind = AttributeKind__$attr.kind;')
 
 				g.writeln('}')
 			}

vlib/v/tests/enum_test.v

@@ -133,3 +133,14 @@ fn test_enum_instance() {
 	s := 'x $filetype z'
 	assert s == 'x unknown z'
 }
+
+enum Bar {
+	baz
+}
+
+fn (_ Bar) baz() {}
+
+fn test_enum_variant_and_method_name_clash() {
+	x := Bar.baz
+	println(x)
+}