[clang-tidy] Use C++ using instead of typedef

Found with modernize-use-using

Signed-off-by: Rosen Penev <rosenp@gmail.com>

.clang-tidy

@@ -1,5 +1,5 @@
 ---
-Checks:          'clang-diagnostic-*,clang-analyzer-*,cert-*,performance-*,portability-*,modernize-use-auto,modernize-loop-convert,modernize-use-bool-literals'
+Checks:          'clang-diagnostic-*,clang-analyzer-*,cert-*,performance-*,portability-*,modernize-use-auto,modernize-loop-convert,modernize-use-bool-literals,modernize-use-using'
 WarningsAsErrors: ''
 HeaderFilterRegex: ''
 AnalyzeTemporaryDtors: false

src/builtin_string.cpp

@@ -133,7 +133,7 @@ class arg_iterator_t {
 
 // This is used by the string subcommands to communicate with the option parser which flags are
 // valid and get the result of parsing the command for flags.
-typedef struct {  //!OCLINT(too many fields)
+using options_t = struct options_t {  //!OCLINT(too many fields)
     bool all_valid = false;
     bool chars_valid = false;
     bool count_valid = false;
@@ -185,7 +185,7 @@ typedef struct {  //!OCLINT(too many fields)
     const wchar_t *arg2 = nullptr;
 
     escape_string_style_t escape_style = STRING_STYLE_SCRIPT;
-} options_t;
+};
 
 /// This handles the `--style=xxx` flag.
 static int handle_flag_1(wchar_t **argv, parser_t &parser, io_streams_t &streams,

src/complete.cpp

@@ -89,7 +89,7 @@ static const wcstring &C_(const wcstring &s) { return s; }
 /// If option is non-empty, it specifies a switch for the command. If \c comp is also not empty, it
 /// contains a list of non-switch arguments that may only follow directly after the specified
 /// switch.
-typedef struct complete_entry_opt {
+using complete_entry_opt_t = struct complete_entry_opt {
     // Text of the option (like 'foo').
     wcstring option;
     // Type of the option: args-oly, short, single_long, or double_long.
@@ -119,8 +119,7 @@ typedef struct complete_entry_opt {
         }
         DIE("unreachable");
     }
-
-} complete_entry_opt_t;
+};
 
 /// Last value used in the order field of completion_entry_t.
 static std::atomic<unsigned int> k_complete_order{0};

src/tinyexpr.cpp

@@ -74,13 +74,13 @@ typedef struct te_expr {
     te_expr *parameters[];
 } te_expr;
 
-typedef struct te_builtin {
+using te_builtin = struct {
     const char *name;
     const void *address;
     int type;
-} te_builtin;
+};
 
-typedef struct state {
+using state = struct {
     union {
         double value;
         const void *function;
@@ -89,7 +89,7 @@ typedef struct state {
     const char *next;
     int type;
     te_error_type_t error;
-} state;
+};
 
 /* Parses the input expression. */
 /* Returns NULL on error. */