Implement operators __static_assert and __static_check

Author: Daniel-Cortez

source/compiler/sc.h

@@ -420,6 +420,8 @@ enum {
   tSLEEP,
   tSTATE,
   tSTATIC,
+  t__STATIC_ASSERT,
+  t__STATIC_CHECK,
   tSTOCK,
   tSWITCH,
   tTAGOF,
@@ -704,6 +706,7 @@ SC_FUNC void emit_parse_line(void);
 SC_FUNC void pragma_deprecated(symbol *sym);
 SC_FUNC void pragma_unused(symbol *sym,int unread,int unwritten);
 SC_FUNC void pragma_nodestruct(symbol *sym);
+SC_FUNC cell do_static_check(int use_warning);
 
 /* function prototypes in SC2.C */
 #define PUSHSTK_P(v)  { stkitem s_; s_.pv=(v); pushstk(s_); }

source/compiler/sc1.c

@@ -1802,6 +1802,13 @@ static void parse(void)
     case tFORWARD:
       funcstub(FALSE);
       break;
+    case t__STATIC_ASSERT:
+    case t__STATIC_CHECK: {
+      int use_warning=(tok==t__STATIC_CHECK);
+      do_static_check(use_warning);
+      needtoken(';');
+      break;
+    } /* case */
     case '}':
       error(54);                /* unmatched closing brace */
       break;
@@ -8530,3 +8537,96 @@ SC_FUNC void pragma_nodestruct(symbol *sym)
   if (sym->ident==iVARIABLE || sym->ident==iARRAY)
     sym->usage |= uNODESTRUCT;
 }
+
+/* do_static_check()
+ * Checks compile-time assertions and triggers an error/warning.
+ *
+ * The 'use_warning' parameter is set to TRUE if warnings are to be
+ * used instead of errors to notify assertion failures.
+ */
+SC_FUNC cell do_static_check(int use_warning)
+{
+  int already_staging,didalloc,optmsg;
+  int ident,index;
+  int bck_litidx;
+  int exprstartfline,exprendfline;
+  cell cidx,val;
+  char *str;
+  const unsigned char *exprstart,*exprend;
+
+  str=NULL;
+  didalloc=optmsg=FALSE;
+  index=0;
+  cidx=0;
+
+  needtoken('(');
+  already_staging=stgget(&index,&cidx);
+  if (!already_staging) {
+    stgset(TRUE);       /* start stage-buffering */
+    errorset(sEXPRMARK,0);
+  } /* if */
+  exprstart=lptr;
+  exprstartfline=fline;
+  ident=expression(&val,NULL,NULL,FALSE);
+  if (ident!=iCONSTEXPR)
+    error(8);           /* must be constant expression */
+  exprend=lptr;
+  exprendfline=fline;
+  stgdel(index,cidx);   /* scratch generated code */
+  if (!already_staging) {
+    errorset(sEXPRRELEASE,0);
+    stgset(FALSE);      /* stop stage-buffering */
+  } /* if */
+
+  /* don't bother allocating space and copying the message
+   * if the expression is true */
+  if (val==0) {
+    if (exprstartfline==exprendfline) {
+      /* skip leading whitespaces */
+      while (*exprstart==' ')
+        exprstart++;
+      /* strip the trailing ',' or ')'. as well as the whitespaces */
+      exprend--;
+      if (*exprend==')' || *exprend==',') {
+        while (*(exprend-1)==' ')
+          exprend--;
+      } /* if */
+      /* copy the expression string */
+      str=malloc((exprend-exprstart+1)*sizeof(char));
+      if (str==NULL)
+        error(103);       /* insufficient memory */
+      memcpy(str,exprstart,exprend-exprstart);
+      str[exprend-exprstart]='\0';
+      didalloc=TRUE;
+    } else {
+      /* Currently there's no reliable way to capture multiline expressions,
+       * as the lexer would only keep the contents of the line the expression
+       * ends at, so try to print "-epression-" instead. Not the prefect
+       * solution, but at least it's better than not printing anything. */
+      str="-expression-";
+    } /* if */
+  } /* if */
+
+  /* read the optional message */
+  if (matchtoken(',')) {
+    if (didalloc) {
+      free(str);
+      didalloc=FALSE;
+    } /* if */
+    optmsg=TRUE;
+    str=parsestringparam(val!=0,&bck_litidx);
+  } /* if */
+
+  if (val==0) {
+    int errnum=use_warning ? 249    /* check failed */
+                           : 110;   /* assertion failed */
+    error(errnum,(str!=NULL) ? str : "");
+    if (didalloc)
+      free(str);
+    else if (optmsg && str!=NULL)
+      litidx=bck_litidx;        /* remove the string from the literal queue */
+  } /* if */
+
+  needtoken(')');
+  return !!val;
+}

source/compiler/sc3.c

@@ -1627,6 +1627,16 @@ static int hier2(value *lval)
     } /* if */
     return FALSE;
   } /* case */
+  case t__STATIC_ASSERT:
+  case t__STATIC_CHECK: {
+    int use_warning=(tok==t__STATIC_CHECK);
+    clear_value(lval);
+    lval->ident=iCONSTEXPR;
+    lval->constval=do_static_check(use_warning);
+    lval->tag=BOOLTAG;
+    pc_sideeffect=TRUE;
+    return FALSE;
+  } /* case */
   case t__EMIT:
     paranthese=matchtoken('(');
     emit_flags |= efEXPR;

source/compiler/sc5.c

@@ -206,7 +206,8 @@ static char *warnmsg[] = {
 /*245*/  "enum increment \"%s %d\" has no effect on zero value (symbol \"%s\")\n",
 /*246*/  "multiplication overflow in enum element declaration (symbol \"%s\")\n",
 /*247*/  "use of operator \"~\" on a \"bool:\" value always results in \"true\"\n",
-/*248*/  "possible misuse of comma operator\n"
+/*248*/  "possible misuse of comma operator\n",
+/*249*/  "check failed: %s\n"
 };
 
 static char *noticemsg[] = {

source/compiler/scvars.c

@@ -111,8 +111,8 @@ SC_VDEFINE char *sc_tokens[] = {
   "__addressof", "assert", "*begin", "break", "case", "char", "const", "continue",
   "default", "defined", "do", "else", "__emit", "*end", "enum", "exit", "for",
   "forward", "goto", "if", "__nameof", "native", "new", "operator", "__pragma",
-  "public", "return", "sizeof", "sleep", "state", "static", "stock", "switch",
-  "tagof", "*then", "while",
+  "public", "return", "sizeof", "sleep", "state", "static", "__static_assert",
+  "__static_check", "stock", "switch", "tagof", "*then", "while",
   "#assert", "#define", "#else", "#elseif", "#emit", "#endif", "#endinput",
   "#endscript", "#error", "#file", "#if", "#include", "#line", "#pragma",
   "#tryinclude", "#undef", "#warning",