libtcc: cleanup -x<filetype> switch code

Abusing filename[0] as type is just too much of a hack.
-- From 0536407204

libtcc.c

@@ -1304,7 +1304,8 @@ ST_FUNC int tcc_add_file_internal(TCCState *s1, const char *filename, int flags,
     parse_flags = 0;
 #ifdef CONFIG_TCC_ASM
     /* if .S file, define __ASSEMBLER__ like gcc does */
-    if ((filetype == TCC_FILETYPE_ASM) || (filetype == TCC_FILETYPE_ASM_PP)) {
+    if (filetype == TCC_FILETYPE_ASM
+     || filetype == TCC_FILETYPE_ASM_PP) {
         tcc_define_symbol(s1, "__ASSEMBLER__", NULL);
         parse_flags = PARSE_FLAG_ASM_FILE;
     }
@@ -2048,33 +2049,29 @@ static void parse_option_D(TCCState *s1, const char *optarg)
 
 static void args_parser_add_file(TCCState *s, const char* filename, int filetype)
 {
-    int len = strlen(filename);
-    char *p = tcc_malloc(len + 2);
-    if (filetype) {
-        *p = filetype;
-    }
-    else {
+    struct filespec *f = tcc_malloc(sizeof *f + strlen(filename));
+
+    if (filetype == 0) {
         /* use a file extension to detect a filetype */
         const char *ext = tcc_fileextension(filename);
         if (ext[0]) {
             ext++;
             if (!strcmp(ext, "S"))
-                *p = TCC_FILETYPE_ASM_PP;
-            else
-            if (!strcmp(ext, "s"))
-                *p = TCC_FILETYPE_ASM;
+                filetype = TCC_FILETYPE_ASM_PP;
+            else if (!strcmp(ext, "s"))
+                filetype = TCC_FILETYPE_ASM;
+            else if (!PATHCMP(ext, "c") || !PATHCMP(ext, "i"))
+                filetype = TCC_FILETYPE_C;
             else
-            if (!PATHCMP(ext, "c") || !PATHCMP(ext, "i"))
-                *p = TCC_FILETYPE_C;
-            else
-                *p = TCC_FILETYPE_BINARY;
-        }
-        else {
-            *p = TCC_FILETYPE_C;
+                filetype = TCC_FILETYPE_BINARY;
+        } else {
+            filetype = TCC_FILETYPE_C;
         }
     }
-    strcpy(p+1, filename);
-    dynarray_add((void ***)&s->files, &s->nb_files, p);
+
+    f->type = filetype;
+    strcpy(f->name, filename);
+    dynarray_add((void ***)&s->files, &s->nb_files, f);
 }
 
 ST_FUNC int tcc_parse_args1(TCCState *s, int argc, char **argv)
@@ -2158,7 +2155,7 @@ ST_FUNC int tcc_parse_args1(TCCState *s, int argc, char **argv)
             tcc_set_lib_path(s, optarg);
             break;
         case TCC_OPTION_l:
-            args_parser_add_file(s, r, TCC_FILETYPE_BINARY);
+            args_parser_add_file(s, optarg, 'l');
             s->nb_libraries++;
             break;
         case TCC_OPTION_pthread:

libtcc.h

@@ -49,10 +49,10 @@ LIBTCCAPI void tcc_undefine_symbol(TCCState *s, const char *sym);
 
 /* add a file (C file, dll, object, library, ld script). Return -1 if error. */
 LIBTCCAPI int tcc_add_file(TCCState *s, const char *filename, int filetype);
-#define TCC_FILETYPE_BINARY 1
-#define TCC_FILETYPE_C      2
-#define TCC_FILETYPE_ASM    3
-#define TCC_FILETYPE_ASM_PP 4
+#define TCC_FILETYPE_BINARY 'b'
+#define TCC_FILETYPE_C      'c'
+#define TCC_FILETYPE_ASM    's'
+#define TCC_FILETYPE_ASM_PP 'S'
 
 /* compile a string containing a C source. Return -1 if error. */
 LIBTCCAPI int tcc_compile_string(TCCState *s, const char *buf);

tcc.c

@@ -307,23 +307,17 @@ int main(int argc, char **argv)
 
     /* compile or add each files or library */
     for(i = ret = 0; i < s->nb_files && ret == 0; i++) {
-        int filetype = *(unsigned char *)s->files[i];
-        const char *filename = s->files[i] + 1;
-        if (filename[0] == '-' && filename[1] == 'l') {
-            if (tcc_add_library(s, filename + 2) < 0) {
-                /* don't fail on -lm as it's harmless to skip math lib */
-                if (strcmp(filename + 2, "m")) {
-                    tcc_error_noabort("cannot find library 'lib%s'", filename + 2);
-                    ret = 1;
-                }
-            }
+        struct filespec *f = s->files[i];
+        if (f->type == 'l') {
+            if (tcc_add_library_err(s, f->name) < 0)
+                ret = 1;
         } else {
             if (1 == s->verbose)
-                printf("-> %s\n", filename);
-            if (tcc_add_file(s, filename, filetype) < 0)
+                printf("-> %s\n", f->name);
+            if (tcc_add_file(s, f->name, f->type) < 0)
                 ret = 1;
             if (!first_file)
-                first_file = filename;
+                first_file = f->name;
         }
     }
 

tcc.h

@@ -850,7 +850,7 @@ struct TCCState {
 #endif
 
     /* used by main and tcc_parse_args only */
-    char **files; /* files seen on command line */
+    struct filespec **files; /* files seen on command line */
     int nb_files; /* number thereof */
     int nb_libraries; /* number of libs thereof */
     char *outfile; /* output filename */
@@ -863,6 +863,10 @@ struct TCCState {
     ParseArgsState *parse_args_state;
 };
 
+struct filespec {
+    char type, name[1];
+};
+
 /* The current value can be: */
 #define VT_VALMASK   0x003f  /* mask for value location, register or: */
 #define VT_CONST     0x0030  /* constant in vc (must be first non register value) */