cgen: fix variable name conflict, when using a C reserved name (#19942)

vlib/v/gen/c/assign.v

@@ -552,7 +552,7 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 					''
 				}
 
-				fn_name := c_name(g.get_ternary_name(ident.name))
+				fn_name := c_fn_name(g.get_ternary_name(ident.name))
 				g.write('${ret_styp} (${msvc_call_conv}*${fn_name}) (')
 				def_pos := g.definitions.len
 				g.fn_decl_params(func.func.params, unsafe { nil }, false)

vlib/v/gen/c/cgen.v

@@ -6394,6 +6394,15 @@ fn (mut g Gen) or_block(var_name string, or_block ast.OrExpr, return_type ast.Ty
 
 @[inline]
 fn c_name(name_ string) string {
+	name := util.no_dots(name_)
+	if c.c_reserved_chk.matches(name) {
+		return '__v_${name}'
+	}
+	return name
+}
+
+@[inline]
+fn c_fn_name(name_ string) string {
 	name := util.no_dots(name_)
 	if c.c_reserved_chk.matches(name) {
 		return '_v_${name}'
@@ -6740,7 +6749,7 @@ fn (mut g Gen) interface_table() string {
 		for k, method in inter_info.methods {
 			methodidx[method.name] = k
 			ret_styp := g.typ(method.return_type)
-			methods_struct_def.write_string('\t${ret_styp} (*_method_${c_name(method.name)})(void* _')
+			methods_struct_def.write_string('\t${ret_styp} (*_method_${c_fn_name(method.name)})(void* _')
 			// the first param is the receiver, it's handled by `void*` above
 			for i in 1 .. method.params.len {
 				arg := method.params[i]
@@ -6865,7 +6874,7 @@ static inline __shared__${interface_name} ${shared_fn_name}(__shared__${cctype}*
 			if st == ast.voidptr_type || st == ast.nil_type {
 				for mname, _ in methodidx {
 					if g.pref.build_mode != .build_module {
-						methods_struct.writeln('\t\t._method_${c_name(mname)} = (void*) 0,')
+						methods_struct.writeln('\t\t._method_${c_fn_name(mname)} = (void*) 0,')
 					}
 				}
 			}
@@ -6975,7 +6984,7 @@ static inline __shared__${interface_name} ${shared_fn_name}(__shared__${cctype}*
 				}
 				if g.pref.build_mode != .build_module && st != ast.voidptr_type
 					&& st != ast.nil_type {
-					methods_struct.writeln('\t\t._method_${c_name(method.name)} = (void*) ${method_call},')
+					methods_struct.writeln('\t\t._method_${c_fn_name(method.name)} = (void*) ${method_call},')
 				}
 			}
 

vlib/v/gen/c/fn.v

@@ -457,7 +457,7 @@ fn (mut g Gen) c_fn_name(node &ast.FnDecl) string {
 	if node.language == .c {
 		name = util.no_dots(name)
 	} else {
-		name = c_name(name)
+		name = c_fn_name(name)
 	}
 
 	if node.generic_names.len > 0 {
@@ -1235,7 +1235,7 @@ fn (mut g Gen) method_call(node ast.CallExpr) {
 			g.expr(node.left)
 		}
 		dot := g.dot_or_ptr(left_type)
-		mname := c_name(node.name)
+		mname := c_fn_name(node.name)
 		g.write('${dot}_typ]._method_${mname}(')
 		if node.left.is_auto_deref_var() && left_type.nr_muls() > 1 {
 			g.write('(')
@@ -1620,7 +1620,7 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 			ast_type := node.args[0].expr as ast.TypeNode
 			// `json.decode(User, s)` => json.decode_User(s)
 			typ := c_name(g.typ(ast_type.typ))
-			fn_name := c_name(name) + '_' + typ
+			fn_name := c_fn_name(name) + '_' + typ
 			g.gen_json_for_type(ast_type.typ)
 			g.empty_line = true
 			g.writeln('// json.decode')
@@ -1647,7 +1647,7 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 		// Skip "C."
 		name = util.no_dots(name[2..])
 	} else {
-		name = c_name(name)
+		name = c_fn_name(name)
 	}
 	if g.pref.translated || g.file.is_translated || node.is_file_translated {
 		// For `[c: 'P_TryMove'] fn p_trymove( ... `
@@ -1713,7 +1713,7 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 			expr := node.args[0].expr
 			typ_sym := g.table.sym(typ)
 			if typ_sym.kind == .interface_ && (typ_sym.info as ast.Interface).defines_method('str') {
-				g.write('${c_name(print_method)}(')
+				g.write('${c_fn_name(print_method)}(')
 				rec_type_name := util.no_dots(g.cc_type(typ, false))
 				g.write('${c_name(rec_type_name)}_name_table[')
 				g.expr(expr)
@@ -1729,9 +1729,9 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 				tmp := g.new_tmp_var()
 				g.write('string ${tmp} = ')
 				g.gen_expr_to_string(expr, typ)
-				g.writeln('; ${c_name(print_method)}(${tmp}); string_free(&${tmp});')
+				g.writeln('; ${c_fn_name(print_method)}(${tmp}); string_free(&${tmp});')
 			} else {
-				g.write('${c_name(print_method)}(')
+				g.write('${c_fn_name(print_method)}(')
 				if expr is ast.ComptimeSelector {
 					key_str := g.get_comptime_selector_key_type(expr)
 					if key_str != '' {

vlib/v/gen/c/json.v

@@ -400,7 +400,7 @@ fn (mut g Gen) gen_sumtype_enc_dec(utyp ast.Type, sym ast.TypeSymbol, mut enc st
 			if variant_sym.kind == .enum_ {
 				enc.writeln('\t\tcJSON_AddItemToObject(o, "${unmangled_variant_name}", ${js_enc_name('u64')}(*${var_data}${field_op}_${variant_typ}));')
 			} else if variant_sym.name == 'time.Time' {
-				enc.writeln('\t\tcJSON_AddItemToObject(o, "${unmangled_variant_name}", ${js_enc_name('i64')}(${var_data}${field_op}_${variant_typ}->_v_unix));')
+				enc.writeln('\t\tcJSON_AddItemToObject(o, "${unmangled_variant_name}", ${js_enc_name('i64')}(${var_data}${field_op}_${variant_typ}->__v_unix));')
 			} else {
 				enc.writeln('\t\tcJSON_AddItemToObject(o, "${unmangled_variant_name}", ${js_enc_name(variant_typ)}(*${var_data}${field_op}_${variant_typ}));')
 			}
@@ -425,7 +425,7 @@ fn (mut g Gen) gen_sumtype_enc_dec(utyp ast.Type, sym ast.TypeSymbol, mut enc st
 				}
 			} else if variant_sym.name == 'time.Time' {
 				enc.writeln('\t\tcJSON_AddItemToObject(o, "_type", cJSON_CreateString("${unmangled_variant_name}"));')
-				enc.writeln('\t\tcJSON_AddItemToObject(o, "value", ${js_enc_name('i64')}(val${field_op}_${variant_typ}->_v_unix));')
+				enc.writeln('\t\tcJSON_AddItemToObject(o, "value", ${js_enc_name('i64')}(val${field_op}_${variant_typ}->__v_unix));')
 			} else {
 				enc.writeln('\t\to = ${js_enc_name(variant_typ)}(*val${field_op}_${variant_typ});')
 				enc.writeln('\t\tcJSON_AddItemToObject(o, "_type", cJSON_CreateString("${unmangled_variant_name}"));')
@@ -832,7 +832,7 @@ fn (mut g Gen) gen_struct_enc_dec(utyp ast.Type, type_info ast.TypeInfo, styp st
 			if field_sym.name == 'time.Time' {
 				// time struct requires special treatment
 				// it has to be encoded as a unix timestamp number
-				enc.writeln('${indent}cJSON_AddItemToObject(o, "${name}", json__encode_u64(${prefix_enc}${op}${c_name(field.name)}._v_unix));')
+				enc.writeln('${indent}cJSON_AddItemToObject(o, "${name}", json__encode_u64(${prefix_enc}${op}${c_name(field.name)}.__v_unix));')
 			} else {
 				if !field.typ.is_any_kind_of_pointer() {
 					if field_sym.kind == .alias && field.typ.has_flag(.option) {

vlib/v/tests/var_name_using_reserved_test.v

@@ -0,0 +1,10 @@
+fn test_var_name_using_reserved() {
+	error := {
+		0: 1
+		1: 2
+		2: 3
+	}
+	ret := error[4] or { 42 }
+	println(ret)
+	assert ret == 42
+}