Revise STDC defines, support -std=iso9899:

Author: fuhsnn

codegen.c

@@ -333,7 +333,7 @@ static bool in_imm_range(int64_t val) {
 }
 
 static bool export_fn(Obj *fn) {
-  if (fn->is_gnu_inline || opt_std == STD_C89 || opt_gnu89_inline)
+  if (fn->is_gnu_inline || opt_gnu89_inline || opt_std < STD_C99)
     return fn->export_fn_gnu;
   return fn->export_fn;
 }

main.c

@@ -210,6 +210,26 @@ static void set_std(bool is_iso, const char *arg) {
   error("unknown c standard");
 }
 
+static void set_std_iso(const char *arg) {
+  char *end;
+  int val = strtoul(arg, &end, 10);
+
+  if (end != arg) {
+    is_iso_std = true;
+
+    switch (val) {
+    case 1990:   opt_std = STD_C89; return;
+    case 199409: opt_std = STD_C94; return;
+    case 1999:   opt_std = STD_C99; return;
+    case 2011:   opt_std = STD_C11; return;
+    case 2017:
+    case 2018:   opt_std = STD_C17; return;
+    case 2024:   opt_std = STD_C23; return;
+    }
+  }
+  error("unknown c standard");
+}
+
 void set_fpic(const char *lvl) {
   opt_fpic = true;
   opt_fpie = false;
@@ -246,11 +266,18 @@ static void build_macros(MacroChangeArr *arr, bool is_asm_pp) {
       define_macro("__STRICT_ANSI__", "1");
 
     switch (opt_std) {
+    case STD_C94: define_macro("__STDC_VERSION__", "199409L"); break;
     case STD_C99: define_macro("__STDC_VERSION__", "199901L"); break;
     case STD_C11: define_macro("__STDC_VERSION__", "201112L"); break;
     case STD_C17: define_macro("__STDC_VERSION__", "201710L"); break;
     case STD_C23: define_macro("__STDC_VERSION__", "202311L"); break;
     }
+
+    if (opt_std >= STD_C99)
+      define_macro("__GNUC_STDC_INLINE__", "1");
+
+    define_macro("__STDC_UTF_16__", "1");
+    define_macro("__STDC_UTF_32__", "1");
   }
 
   for (int i = 0; i < arr->len; i++) {
@@ -594,6 +621,8 @@ static void parse_args(int argc, char **argv, bool *run_ld, bool *no_fork) {
         set_std(true, arg);
       else if (startswith(arg, &arg, "gnu"))
         set_std(false, arg);
+      else if (startswith(arg, &arg, "iso9899:"))
+        set_std_iso(arg);
       else
         error("unknown c standard");
       continue;

parse.c

@@ -313,7 +313,7 @@ static Scope *base_scope(void) {
 
 static Scope *decl_scope(void) {
   Scope *sc = scope;
-  while (sc->is_temporary || (sc->is_stmt && opt_std == STD_C89))
+  while (sc->is_temporary || (sc->is_stmt && opt_std < STD_C99))
     sc = sc->parent;
   return sc;
 }
@@ -1259,7 +1259,7 @@ static Type *declspec(Token **rest, Token *tok, VarAttr *attr, StorageClass ctx)
     error_tok(tok, "invalid storage class");
 
   if (!ty) {
-    if (opt_std == STD_C89) {
+    if (opt_std < STD_C99) {
       ty = ty_int;
     } else if (opt_std >= STD_C23 && (attr->strg & SC_AUTO)) {
       ty = new_type(TY_AUTO, -1, 0);
@@ -5529,7 +5529,7 @@ static Node *primary(Token **rest, Token *tok) {
       if (node)
         return node;
 
-      if (opt_std == STD_C89) {
+      if (opt_std < STD_C99) {
         Type *ty = func_type(ty_int, tok);
         ty->is_oldstyle = true;
         return new_var_node(func_prototype2(ty, &(VarAttr){0}, tok), tok);

preprocess.c

@@ -1773,11 +1773,10 @@ void init_macros(void) {
   define_macro("__STDC_EMBED_FOUND__", "1");
   define_macro("__STDC_EMBED_NOT_FOUND__", "0");
   define_macro("__STDC_HOSTED__", "1");
-  define_macro("__STDC_NO_COMPLEX__", "1");
-  define_macro("__STDC_UTF_16__", "1");
-  define_macro("__STDC_UTF_32__", "1");
   define_macro("__STDC__", "1");
 
+  define_macro("__STDC_NO_COMPLEX__", "1");
+
   define_macro("__STDC_DEFER_TS25755__", "1");
 
   define_macro("__C99_MACRO_WITH_VA_ARGS", "1");

slimcc.h

@@ -912,7 +912,7 @@ void run_linker(StringArray *paths, StringArray *inputs, const char *output);
 // main.c
 //
 
-typedef enum { STD_C89, STD_C99, STD_C11, STD_C17, STD_C23 } StdVer;
+typedef enum { STD_C89, STD_C94, STD_C99, STD_C11, STD_C17, STD_C23 } StdVer;
 
 void cleanup_exit(int status) NORETURN;
 bool file_exists(const char *path);