remove some dyncast calls (#15488)

compiler/src/dmd/declaration.d

@@ -626,7 +626,7 @@ extern (C++) final class TupleDeclaration : Declaration
             for (size_t i = 0; i < objects.length; i++)
             {
                 RootObject o = (*objects)[i];
-                if (o.dyncast() != DYNCAST.type)
+                if (!o.isType())
                 {
                     //printf("\tnot[%d], %p, %d\n", i, o, o.dyncast());
                     return null;

compiler/src/dmd/dinterpret.d

@@ -7706,7 +7706,7 @@ private void removeHookTraceImpl(ref CallExp ce, ref FuncDeclaration fd)
     // Get the Hook from the second template parameter
     TemplateInstance templateInstance = fd.parent.isTemplateInstance;
     RootObject hook = (*templateInstance.tiargs)[1];
-    assert(hook.dyncast() == DYNCAST.dsymbol, "Expected _d_HookTraceImpl's second template parameter to be an alias to the hook!");
+    assert(hook.isDsymbol(), "Expected _d_HookTraceImpl's second template parameter to be an alias to the hook!");
     fd = (cast(Dsymbol)hook).isFuncDeclaration;
 
     // Remove the first three trace parameters

compiler/src/dmd/dscope.d

@@ -168,7 +168,7 @@ extern (C++) struct Scope
         sc.minst = _module;
         sc.scopesym = new ScopeDsymbol();
         sc.scopesym.symtab = new DsymbolTable();
-	sc.eSink = eSink;
+        sc.eSink = eSink;
         // Add top level package as member of this global scope
         Dsymbol m = _module;
         while (m.parent)

compiler/src/dmd/dsymbol.d

@@ -353,9 +353,9 @@ extern (C++) class Dsymbol : ASTNode
     {
         if (this == o)
             return true;
-        if (o.dyncast() != DYNCAST.dsymbol)
+        const s = o.isDsymbol();
+        if (!s)
             return false;
-        auto s = cast(Dsymbol)o;
         // Overload sets don't have an ident
         // Function-local declarations may have identical names
         // if they are declared in different scopes

compiler/src/dmd/func.d

@@ -4708,9 +4708,9 @@ void errorSupplementalInferredAttr(FuncDeclaration fd, int maxDepth, bool deprec
                     s.arg0 ? s.arg0.toChars() : "", s.arg1 ? s.arg1.toChars() : "", s.arg2 ? s.arg2.toChars() : "");
             }
         }
-        else if (s.arg0.dyncast() == DYNCAST.dsymbol)
+        else if (auto sa = s.arg0.isDsymbol())
         {
-            if (FuncDeclaration fd2 = (cast(Dsymbol) s.arg0).isFuncDeclaration())
+            if (FuncDeclaration fd2 = sa.isFuncDeclaration())
             {
                 if (maxDepth > 0)
                 {

compiler/src/dmd/nogc.d

@@ -19,6 +19,7 @@ import dmd.aggregate;
 import dmd.astenums;
 import dmd.declaration;
 import dmd.dscope;
+import dmd.dtemplate : isDsymbol;
 import dmd.errors;
 import dmd.expression;
 import dmd.func;
@@ -263,6 +264,7 @@ private FuncDeclaration stripHookTraceImpl(FuncDeclaration fd)
     // Get the Hook from the second template parameter
     auto templateInstance = fd.parent.isTemplateInstance;
     RootObject hook = (*templateInstance.tiargs)[1];
-    assert(hook.dyncast() == DYNCAST.dsymbol, "Expected _d_HookTraceImpl's second template parameter to be an alias to the hook!");
+    Dsymbol s = hook.isDsymbol();
-    return (cast(Dsymbol)hook).isFuncDeclaration;
+    assert(s, "Expected _d_HookTraceImpl's second template parameter to be an alias to the hook!");
+    return s.isFuncDeclaration;
 }

compiler/src/dmd/typesem.d

@@ -530,12 +530,10 @@ extern(C++) Type typeSemantic(Type type, const ref Loc loc, Scope* sc)
             }
 
             RootObject o = (*tup.objects)[cast(size_t)d];
-            if (o.dyncast() != DYNCAST.type)
+            if (auto tt = o.isType())
-            {
+                return tt.addMod(mtype.mod);
-                .error(loc, "`%s` is not a type", mtype.toChars());
+            .error(loc, "`%s` is not a type", mtype.toChars());
-                return error();
+            return error();
-            }
-            return (cast(Type)o).addMod(mtype.mod);
         }
 
         if (t && t.ty == Terror)