Issue 11169 - __traits(isAbstractClass) prematurely sets a class to b…

…e abstract

src/aggregate.h

@@ -58,6 +58,13 @@ enum StructPOD
     ISPODfwd,           // POD not yet computed
 };
 
+enum Abstract
+{
+    ABSfwdref = 0,      // whether an abstract class is not yet computed
+    ABSyes,             // is abstract class
+    ABSno,              // is not abstract class
+};
+
 FuncDeclaration *hasIdentityOpAssign(AggregateDeclaration *ad, Scope *sc);
 FuncDeclaration *buildOpAssign(StructDeclaration *sd, Scope *sc);
 bool needOpEquals(StructDeclaration *sd);
@@ -272,7 +279,7 @@ class ClassDeclaration : public AggregateDeclaration
     bool com;                           // true if this is a COM class (meaning it derives from IUnknown)
     bool cpp;                           // true if this is a C++ interface
     bool isscope;                       // true if this is a scope class
-    bool isabstract;                    // true if abstract class
+    Abstract isabstract;                // 0: fwdref, 1: is abstract class, 2: not abstract
     int inuse;                          // to prevent recursive attempts
     Baseok baseok;                      // set the progress of base classes resolving
     Objc_ClassDeclaration objc;

src/class.c

@@ -231,7 +231,7 @@ ClassDeclaration::ClassDeclaration(Loc loc, Identifier *id, BaseClasses *basecla
     com = false;
     cpp = false;
     isscope = false;
-    isabstract = false;
+    isabstract = ABSfwdref;
     inuse = 0;
     baseok = BASEOKnone;
     objc.objc = false;
@@ -316,7 +316,7 @@ void ClassDeclaration::semantic(Scope *sc)
         if (storage_class & STCscope)
             isscope = true;
         if (storage_class & STCabstract)
-            isabstract = true;
+            isabstract = ABSyes;
 
         userAttribDecl = sc->userAttribDecl;
 
@@ -1263,19 +1263,55 @@ bool ClassDeclaration::isCPPinterface() const
 
 bool ClassDeclaration::isAbstract()
 {
-    if (isabstract)
-        return true;
+    if (isabstract != ABSfwdref)
+        return isabstract == ABSyes;
+
+    /* Bugzilla 11169: Resolve forward references to all class member functions,
+     * and determine whether this class is abstract.
+     */
+    struct SearchAbstract
+    {
+        static int fp(Dsymbol *s, void* param)
+        {
+            FuncDeclaration *fd = s->isFuncDeclaration();
+            if (!fd)
+                return 0;
+            if (fd->storage_class & STCstatic)
+                return 0;
+
+            if (fd->_scope)
+                fd->semantic(NULL);
+
+            if (fd->isAbstract())
+                return 1;
+            return 0;
+        }
+    };
+
+    for (size_t i = 0; i < members->dim; i++)
+    {
+        Dsymbol *s = (*members)[i];
+        if (s->apply(&SearchAbstract::fp, this))
+        {
+            isabstract = ABSyes;
+            return true;
+        }
+    }
+
+    /* Iterate inherited member functions and check their abstract attribute.
+     */
     for (size_t i = 1; i < vtbl.dim; i++)
     {
         FuncDeclaration *fd = vtbl[i]->isFuncDeclaration();
-
-        //printf("\tvtbl[%d] = %p\n", i, fd);
+        //if (fd) printf("\tvtbl[%d] = [%s] %s\n", i, fd->loc.toChars(), fd->toChars());
         if (!fd || fd->isAbstract())
         {
-            isabstract = true;
+            isabstract = ABSyes;
             return true;
         }
     }
+
+    isabstract = ABSno;
     return false;
 }
 

src/dsymbol.c

@@ -654,6 +654,17 @@ bool Dsymbol::needThis()
     return false;
 }
 
+/*********************************
+ * Iterate this dsymbol or members of this scoped dsymbol, then
+ * call `fp` with the found symbol and `param`.
+ * Params:
+ *  fp = function pointer to process the iterated symbol.
+ *       If it returns nonzero, the iteration will be aborted.
+ *  param = a parameter passed to fp.
+ * Returns:
+ *  nonzero if the iteration is aborted by the return value of fp,
+ *  or 0 if it's completed.
+ */
 int Dsymbol::apply(Dsymbol_apply_ft_t fp, void *param)
 {
     return (*fp)(this, param);

src/func.c

@@ -383,15 +383,15 @@ void FuncDeclaration::semantic(Scope *sc)
     assert(semanticRun <= PASSsemantic);
     semanticRun = PASSsemantic;
 
-    parent = sc->parent;
-    Dsymbol *parent = toParent();
-
     if (_scope)
     {
         sc = _scope;
         _scope = NULL;
     }
 
+    parent = sc->parent;
+    Dsymbol *parent = toParent();
+
     unsigned dprogress_save = Module::dprogress;
 
     foverrides.setDim(0);       // reset in case semantic() is being retried for this function
@@ -714,7 +714,7 @@ void FuncDeclaration::semantic(Scope *sc)
         }
 
         if (storage_class & STCabstract)
-            cd->isabstract = true;
+            cd->isabstract = ABSyes;
 
         // if static function, do not put in vtbl[]
         if (!isVirtual())

src/template.c

@@ -8504,6 +8504,8 @@ bool TemplateMixin::oneMember(Dsymbol **ps, Identifier *ident)
 
 int TemplateMixin::apply(Dsymbol_apply_ft_t fp, void *param)
 {
+    if (_scope) // if fwd reference
+        semantic(NULL); // try to resolve it
     if (members)
     {
         for (size_t i = 0; i < members->dim; i++)