Merge pull request #2499 from kugelfuhr/kugelfuhr/disable-recursive-calls-to-main

Disallow recursive calls to main() in cc65 mode

src/cc65/codegen.c

@@ -507,13 +507,13 @@ void g_enter (unsigned flags, unsigned argsize)
 
 
 
-void g_leave (int IsMainFunc)
+void g_leave (int DoCleanup)
 /* Function epilogue */
 {
-    /* In the main function nothing has to be dropped because the program
-    ** is terminated anyway.
+    /* In the main function in cc65 mode nothing has to be dropped because
+    ** the program is terminated anyway.
     */
-    if (!IsMainFunc) {
+    if (DoCleanup) {
         /* How many bytes of locals do we have to drop? */
         unsigned ToDrop = (unsigned) -StackPtr;
 

src/cc65/codegen.h

@@ -247,7 +247,7 @@ void g_scale (unsigned flags, long val);
 void g_enter (unsigned flags, unsigned argsize);
 /* Function prologue */
 
-void g_leave (int IsMainFunc);
+void g_leave (int DoCleanup);
 /* Function epilogue */
 
 

src/cc65/expr.c

@@ -1219,9 +1219,6 @@ static void Primary (ExprDesc* E)
             /* Is the symbol known? */
             if (Sym) {
 
-                /* We found the symbol - skip the name token */
-                NextToken ();
-
                 /* Check for illegal symbol types */
                 CHECK ((Sym->Flags & SC_TYPEMASK) != SC_LABEL);
                 if ((Sym->Flags & SC_TYPEMASK) == SC_TYPEDEF) {
@@ -1230,9 +1227,14 @@ static void Primary (ExprDesc* E)
                     /* Assume an int type to make E valid */
                     E->Flags = E_LOC_STACK | E_RTYPE_LVAL;
                     E->Type  = type_int;
+                    /* Skip the erroneous token */
+                    NextToken ();
                     break;
                 }
 
+                /* Skip the name token */
+                NextToken ();
+
                 /* Mark the symbol as referenced */
                 Sym->Flags |= SC_REF;
 
@@ -1286,7 +1288,23 @@ static void Primary (ExprDesc* E)
                 ** rvalue, too, because we cannot store anything in a function.
                 ** So fix the flags depending on the type.
                 */
-                if (IsTypeArray (E->Type) || IsTypeFunc (E->Type)) {
+                if (IsTypeArray (E->Type)) {
+                    ED_AddrExpr (E);
+                } else if (IsTypeFunc (E->Type)) {
+                    /* In cc65 mode we cannot call or take the address of
+                    ** main().
+                    */
+                    if (IS_Get (&Standard) == STD_CC65 &&
+                        strcmp (Sym->Name, "main") == 0) {
+                        /* Adjust the error message depending on a call or an
+                        ** address operation.
+                        */
+                        if (CurTok.Tok == TOK_LPAREN) {
+                            Error ("'main' must not be called recursively");
+                        } else {
+                            Error ("The address of 'main' cannot be taken");
+                        }
+                    }
                     ED_AddrExpr (E);
                 }
 

src/cc65/function.c

@@ -646,13 +646,17 @@ void NewFunc (SymEntry* Func, FuncDesc* D)
     /* Output the function exit code label */
     g_defcodelabel (F_GetRetLab (CurrentFunc));
 
-    /* Restore the register variables (not necessary for main function) */
-    if (!F_IsMainFunc (CurrentFunc)) {
+    /* Restore the register variables (not necessary for the main function in
+    ** cc65 mode)
+    */
+    int CleanupOnExit = (IS_Get (&Standard) != STD_CC65) ||
+                        !F_IsMainFunc (CurrentFunc);
+    if (CleanupOnExit) {
         F_RestoreRegVars (CurrentFunc);
     }
 
     /* Generate the exit code */
-    g_leave (F_IsMainFunc (CurrentFunc));
+    g_leave (CleanupOnExit);
 
     /* Emit references to imports/exports */
     EmitExternals ();

src/cc65/locals.c

@@ -111,6 +111,13 @@ static void ParseRegisterDecl (Declarator* Decl, int Reg)
     /* Get the size of the variable */
     unsigned Size = SizeOf (Decl->Type);
 
+    /* Check if this is the main function and we are in cc65 mode. If so, we
+    ** won't save the old contents of the register variables since in cc65
+    ** mode main() may not be called recursively.
+    */
+    int SaveRegVars = (IS_Get (&Standard) != STD_CC65) ||
+                      !F_IsMainFunc (CurrentFunc);
+
     /* Check for an optional initialization */
     if (CurTok.Tok == TOK_ASSIGN) {
 
@@ -126,13 +133,13 @@ static void ParseRegisterDecl (Declarator* Decl, int Reg)
         /* Save the current contents of the register variable on stack. This is
         ** not necessary for the main function.
         */
-        if (!F_IsMainFunc (CurrentFunc)) {
+        if (SaveRegVars) {
             g_save_regvars (Reg, Size);
         }
 
         /* Add the symbol to the symbol table. We do that now, because for
         ** register variables the current stack pointer is implicitly used
-        ** as location for the save area (unused in case of main()).
+        ** as location for the save area (maybe unused in case of main()).
         */
         Sym = AddLocalSym (Decl->Ident, Decl->Type, Decl->StorageClass, Reg);
 
@@ -187,14 +194,14 @@ static void ParseRegisterDecl (Declarator* Decl, int Reg)
         /* Save the current contents of the register variable on stack. This is
         ** not necessary for the main function.
         */
-        if (!F_IsMainFunc (CurrentFunc)) {
+        if (SaveRegVars) {
             F_AllocLocalSpace (CurrentFunc);
             g_save_regvars (Reg, Size);
         }
 
         /* Add the symbol to the symbol table. We do that now, because for
         ** register variables the current stack pointer is implicitly used
-        ** as location for the save area (unused in case of main()).
+        ** as location for the save area (maybe unused in case of main()).
         */
         Sym = AddLocalSym (Decl->Ident, Decl->Type, Decl->StorageClass, Reg);
     }