Introduce compatibility mode

The compiler now has a new command-line option (-Z) that toggles
between normal mode and "compatibility" mode.

When this mode is on the compiler attempts to be compatible with
the current SA-MP compiler, which allows compiling old SA-MP scripts
that would not compile otherwise and at the same time benefiting
from new features and bug fixes.

In particular, this allows compiling code that relies on the auto
generated #include guard symbols (_inc_filename).

And in case you're wondering, the Z in "-Z" does not stand for "Zeex",
it just means "a letter that is unlikely to be ever taken by another
option".

This closes #23.

source/compiler/sc.h

@@ -815,6 +815,7 @@ SC_VDECL int sc_curstates;    /* ID of the current state list */
 SC_VDECL int pc_optimize;     /* (peephole) optimization level */
 SC_VDECL int pc_memflags;     /* special flags for the stack/heap usage */
 SC_VDECL int pc_naked;        /* if true mark following function as naked */
+SC_VDECL int pc_compat;       /* running in compatibility mode? */
 
 SC_VDECL constvalue sc_automaton_tab; /* automaton table */
 SC_VDECL constvalue sc_state_tab;     /* state table */

source/compiler/sc1.c

@@ -66,6 +66,7 @@
 #include "svnrev.h"
 #define VERSION_STR "3.2." SVN_REVSTR
 #define VERSION_INT        0x030A
+#define VERSION_INT_COMPAT 0x0302
 
 static void resetglobals(void);
 static void initglobals(void);
@@ -1128,6 +1129,9 @@ static void parseoptions(int argc,char **argv,char *oname,char *ename,char *pnam
             about();
         } /* if */
         break;
+      case 'Z':
+        pc_compat=toggle_option(ptr,pc_compat);
+        break;
       case '\\':                /* use \ instead for escape characters */
         sc_ctrlchar='\\';
         break;
@@ -1391,6 +1395,7 @@ static void about(void)
     pc_printf("         -w<num>  disable a specific warning by its number\n");
     pc_printf("         -X<num>  abstract machine size limit in bytes\n");
     pc_printf("         -XD<num> abstract machine data/stack size limit in bytes\n");
+    pc_printf("         -Z[+/-]  run in compatibility mode (default=%c)\n",pc_compat ? '+' : '-');
     pc_printf("         -\\       use '\\' for escape characters\n");
     pc_printf("         -^       use '^' for escape characters\n");
     pc_printf("         -;[+/-]  require a semicolon to end each statement (default=%c)\n", sc_needsemicolon ? '+' : '-');
@@ -1453,7 +1458,7 @@ static void setconstants(void)
   add_constant("charmax",~(-1 << sCHARBITS) - 1,sGLOBAL,0);
   add_constant("ucharmax",(1 << (sizeof(cell)-1)*8)-1,sGLOBAL,0);
 
-  add_constant("__Pawn",VERSION_INT,sGLOBAL,0);
+  add_constant("__Pawn",pc_compat ? VERSION_INT_COMPAT : VERSION_INT,sGLOBAL,0);
   add_constant("__line",0,sGLOBAL,0);
 
   debug=0;

source/compiler/sc2.c

@@ -235,6 +235,7 @@ static void doinclude(int silent)
   char *ptr;
   char c;
   int i, result;
+  int included=FALSE;
 
   while (*lptr<=' ' && *lptr!='\0')         /* skip leading whitespace */
     lptr++;
@@ -262,6 +263,7 @@ static void doinclude(int silent)
   if (c!='\0')
     check_empty(lptr+1);        /* verify that the rest of the line is whitespace */
 
+  if (pc_compat) {
     /* create a symbol from the name of the include file; this allows the system
      * to test for multiple inclusions
      */
@@ -270,7 +272,10 @@ static void doinclude(int silent)
       strlcat(symname,ptr+1,sizeof symname);
     else
       strlcat(symname,name,sizeof symname);
-  if (find_symbol(&glbtab,symname,fcurrent,-1,NULL)==NULL) {
+    included=find_symbol(&glbtab,symname,fcurrent,-1,NULL)!=NULL;
+  } /* if */
+
+  if (!included) {
     /* constant is not present, so this file has not been included yet */
 
     /* Include files between "..." or without quotes are read from the current
@@ -278,9 +283,9 @@ static void doinclude(int silent)
      * between <...> are only read from the list of include directories.
      */
     result=plungefile(name,(c!='>'),TRUE);
-    if (result)
+    if (result && pc_compat)
       add_constant(symname,1,sGLOBAL,0);
-    else if (!silent)
+    else if (!result && !silent)
       error(100,name);          /* cannot read from ... (fatal error) */
   } /* if */
 }

source/compiler/scvars.c

@@ -91,6 +91,7 @@ SC_VDEFINE int sc_curstates=0;     /* ID of the current state list */
 SC_VDEFINE int pc_optimize=sOPTIMIZE_NOMACRO; /* (peephole) optimization level */
 SC_VDEFINE int pc_memflags=0;      /* special flags for the stack/heap usage */
 SC_VDEFINE int pc_naked=FALSE;     /* if true mark following function as naked */
+SC_VDEFINE int pc_compat=FALSE;    /* running in compatibility mode? */
 
 SC_VDEFINE constvalue sc_automaton_tab = { NULL, "", 0, 0}; /* automaton table */
 SC_VDEFINE constvalue sc_state_tab = { NULL, "", 0, 0};   /* state table */