4329 Do not show error messages that refer to __error

This suppresses all spurious errors in the test cases in the bug report.
The "struct literal has no effect" error message is not spurious, even
when there is an __error in the literal, so it is not suppressed.

Additionally, the spurious "xxx is used as a type" error message which occurs
after an error involving xxx, is now suppressed.

src/attrib.c

@@ -949,6 +949,8 @@ void PragmaDeclaration::semantic(Scope *sc)
             e = e->semantic(sc);
             e = e->optimize(WANTvalue | WANTinterpret);
             args->data[0] = (void *)e;
+            if (e->op == TOKerror)
+                goto Lnodecl;
             if (e->op != TOKstring)
                 error("string expected for library name, not '%s'", e->toChars());
             else if (global.params.verbose)

src/cast.c

@@ -775,6 +775,8 @@ Expression *Expression::castTo(Scope *sc, Type *t)
 #endif
     if (type == t)
         return this;
+    if (op == TOKerror)
+        return this;
     Expression *e = this;
     Type *tb = t->toBasetype();
     Type *typeb = type->toBasetype();

src/expression.c

@@ -3627,6 +3627,8 @@ Expression *ScopeExp::semantic(Scope *sc)
             }
             //printf("sds = %s, '%s'\n", sds->kind(), sds->toChars());
         }
+        if (global.errors)
+            return new ErrorExp();
     }
     else
     {
@@ -5622,6 +5624,8 @@ Expression *CompileExp::semantic(Scope *sc)
 #endif
     UnaExp::semantic(sc);
     e1 = resolveProperties(sc, e1);
+    if (e1->op == TOKerror)
+        return e1;
     if (!e1->type->isString())
     {
         error("argument to mixin must be a string type, not %s\n", e1->type->toChars());
@@ -6364,6 +6368,8 @@ Expression *DotTemplateInstanceExp::semantic(Scope *sc)
     Expression *e = new DotIdExp(loc, e1, ti->name);
 L1:
     e = e->semantic(sc);
+    if (e->op == TOKerror)
+        return e;
     if (e->op == TOKdottd)
     {
         if (global.errors)
@@ -7685,6 +7691,8 @@ Expression *DeleteExp::semantic(Scope *sc)
     UnaExp::semantic(sc);
     e1 = resolveProperties(sc, e1);
     e1 = e1->toLvalue(sc, NULL);
+    if (e1->op == TOKerror)
+        return e1;
     type = Type::tvoid;
 
     tb = e1->type->toBasetype();

src/mtype.c

@@ -5615,8 +5615,11 @@ void TypeQualified::resolveHelper(Loc loc, Scope *sc,
                     *pe = e;
                 }
                 else
+                {
                   Lerror:
                     error(loc, "identifier '%s' of '%s' is not defined", id->toChars(), toChars());
+                    *pe = new ErrorExp();
+                }
                 return;
             }
         L2:
@@ -5715,6 +5718,7 @@ void TypeQualified::resolveHelper(Loc loc, Scope *sc,
             else
                 error(loc, "undefined identifier %s", p);
         }
+        *pt = Type::terror;
     }
 }
 

src/statement.c

@@ -321,6 +321,8 @@ Statements *CompileStatement::flatten(Scope *sc)
     exp = exp->semantic(sc);
     exp = resolveProperties(sc, exp);
     exp = exp->optimize(WANTvalue | WANTinterpret);
+    if (exp->op == TOKerror)
+        return NULL;
     if (exp->op != TOKstring)
     {   error("argument to mixin must be a string, not (%s)", exp->toChars());
         return NULL;
@@ -1966,6 +1968,9 @@ Statement *ForeachStatement::semantic(Scope *sc)
             }
             break;
         }
+        case Terror:
+            s = NULL;
+            break;
 
         default:
             error("foreach: %s is not an aggregate type", aggr->type->toChars());
@@ -2957,7 +2962,7 @@ Statement *CaseStatement::semantic(Scope *sc)
             }
         }
 
-        if (exp->op != TOKstring && exp->op != TOKint64)
+        if (exp->op != TOKstring && exp->op != TOKint64 && exp->op != TOKerror)
         {
             error("case must be a string or an integral constant, not %s", exp->toChars());
             exp = new IntegerExp(0);
@@ -3068,6 +3073,9 @@ Statement *CaseRangeStatement::semantic(Scope *sc)
     last = last->optimize(WANTvalue | WANTinterpret);
     uinteger_t lval = last->toInteger();
 
+    if (first->op == TOKerror || last->op == TOKerror)
+        return statement ? statement->semantic(sc) : NULL;
+
     if ( (first->type->isunsigned()  &&  fval > lval) ||
         (!first->type->isunsigned()  &&  (sinteger_t)fval > (sinteger_t)lval))
     {
@@ -3982,6 +3990,8 @@ Statement *WithStatement::semantic(Scope *sc)
     //printf("WithStatement::semantic()\n");
     exp = exp->semantic(sc);
     exp = resolveProperties(sc, exp);
+    if (exp->op == TOKerror)
+        return NULL;
     if (exp->op == TOKimport)
     {   ScopeExp *es = (ScopeExp *)exp;
 
@@ -4440,6 +4450,8 @@ Statement *ThrowStatement::semantic(Scope *sc)
 #endif
     exp = exp->semantic(sc);
     exp = resolveProperties(sc, exp);
+    if (exp->op == TOKerror)
+        return this;
     ClassDeclaration *cd = exp->type->toBasetype()->isClassHandle();
     if (!cd || ((cd != ClassDeclaration::throwable) && !ClassDeclaration::throwable->isBaseOf(cd, NULL)))
         error("can only throw class objects derived from Throwable, not type %s", exp->type->toChars());