Fix Issue 5973 - alias this is not considered with superclass lookup

dlang · Oct 16, 2018 · 4a9ad74 · 4a9ad74
1 parent 1bab5f3
commit 4a9ad74
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Showing 4 changed files with 109 additions and 51 deletions.
diff --git a/src/dmd/aliasthis.d b/src/dmd/aliasthis.d
@@ -63,50 +63,61 @@ extern (C++) final class AliasThis : Dsymbol
 
 Expression resolveAliasThis(Scope* sc, Expression e, bool gag = false)
 {
-    AggregateDeclaration ad = isAggregate(e.type);
-    if (ad && ad.aliasthis)
+    for (AggregateDeclaration ad = isAggregate(e.type); ad;)
     {
-        uint olderrors = gag ? global.startGagging() : 0;
-        Loc loc = e.loc;
-        Type tthis = (e.op == TOK.type ? e.type : null);
-        e = new DotIdExp(loc, e, ad.aliasthis.ident);
-        e = e.expressionSemantic(sc);
-        if (tthis && ad.aliasthis.needThis())
+        if (ad.aliasthis)
         {
-            if (e.op == TOK.variable)
+            uint olderrors = gag ? global.startGagging() : 0;
+            Loc loc = e.loc;
+            Type tthis = (e.op == TOK.type ? e.type : null);
+            e = new DotIdExp(loc, e, ad.aliasthis.ident);
+            e = e.expressionSemantic(sc);
+            if (tthis && ad.aliasthis.needThis())
             {
-                if (auto fd = (cast(VarExp)e).var.isFuncDeclaration())
+                if (e.op == TOK.variable)
                 {
-                    // https://issues.dlang.org/show_bug.cgi?id=13009
-                    // Support better match for the overloaded alias this.
-                    bool hasOverloads;
-                    if (auto f = fd.overloadModMatch(loc, tthis, hasOverloads))
+                    if (auto fd = (cast(VarExp)e).var.isFuncDeclaration())
                     {
-                        if (!hasOverloads)
-                            fd = f;     // use exact match
-                        e = new VarExp(loc, fd, hasOverloads);
-                        e.type = f.type;
-                        e = new CallExp(loc, e);
-                        goto L1;
+                        // https://issues.dlang.org/show_bug.cgi?id=13009
+                        // Support better match for the overloaded alias this.
+                        bool hasOverloads;
+                        if (auto f = fd.overloadModMatch(loc, tthis, hasOverloads))
+                        {
+                            if (!hasOverloads)
+                                fd = f;     // use exact match
+                            e = new VarExp(loc, fd, hasOverloads);
+                            e.type = f.type;
+                            e = new CallExp(loc, e);
+                            goto L1;
+                        }
                     }
                 }
+                /* non-@property function is not called inside typeof(),
+                 * so resolve it ahead.
+                 */
+                {
+                    int save = sc.intypeof;
+                    sc.intypeof = 1; // bypass "need this" error check
+                    e = resolveProperties(sc, e);
+                    sc.intypeof = save;
+                }
+            L1:
+                e = new TypeExp(loc, new TypeTypeof(loc, e));
+                e = e.expressionSemantic(sc);
             }
-            /* non-@property function is not called inside typeof(),
-             * so resolve it ahead.
-             */
-            {
-                int save = sc.intypeof;
-                sc.intypeof = 1; // bypass "need this" error check
-                e = resolveProperties(sc, e);
-                sc.intypeof = save;
-            }
-        L1:
-            e = new TypeExp(loc, new TypeTypeof(loc, e));
-            e = e.expressionSemantic(sc);
+            e = resolveProperties(sc, e);
+            if (gag && global.endGagging(olderrors))
+                e = null;
+        }
+
+        import dmd.dclass : ClassDeclaration;
+        auto cd = ad.isClassDeclaration();
+        if ((!e || !ad.aliasthis) && cd && cd.baseClass && cd.baseClass != ClassDeclaration.object)
+        {
+            ad = cd.baseClass;
+            continue;
         }
-        e = resolveProperties(sc, e);
-        if (gag && global.endGagging(olderrors))
-            e = null;
+        break;
     }
     return e;
 }
diff --git a/src/dmd/expressionsem.d b/src/dmd/expressionsem.d
@@ -2353,19 +2353,29 @@ private extern (C++) final class ExpressionSemanticVisitor : Visitor
 
         if (hasThis(sc))
         {
-            AggregateDeclaration ad = sc.getStructClassScope();
-            if (ad && ad.aliasthis)
+            for (AggregateDeclaration ad = sc.getStructClassScope(); ad;)
             {
-                Expression e;
-                e = new ThisExp(exp.loc);
-                e = new DotIdExp(exp.loc, e, ad.aliasthis.ident);
-                e = new DotIdExp(exp.loc, e, exp.ident);
-                e = e.trySemantic(sc);
-                if (e)
+                if (ad.aliasthis)
                 {
-                    result = e;
-                    return;
+                    Expression e;
+                    e = new ThisExp(exp.loc);
+                    e = new DotIdExp(exp.loc, e, ad.aliasthis.ident);
+                    e = new DotIdExp(exp.loc, e, exp.ident);
+                    e = e.trySemantic(sc);
+                    if (e)
+                    {
+                        result = e;
+                        return;
+                    }
                 }
+
+                auto cd = ad.isClassDeclaration();
+                if (cd && cd.baseClass && cd.baseClass != ClassDeclaration.object)
+                {
+                    ad = cd.baseClass;
+                    continue;
+                }
+                break;
             }
         }
 

diff --git a/src/dmd/typesem.d b/src/dmd/typesem.d
@@ -3436,16 +3436,12 @@ private extern(C++) final class DotExpVisitor : Visitor
 
             /* See if we should forward to the alias this.
              */
-            if (sym.aliasthis)
+            auto alias_e = resolveAliasThis(sc, e, gagError);
+            if (alias_e && alias_e != e)
             {
                 /* Rewrite e.ident as:
                  *  e.aliasthis.ident
                  */
-                auto alias_e = resolveAliasThis(sc, e, gagError);
-
-                if (!alias_e)
-                    return returnExp(null);
-
                 auto die = new DotIdExp(e.loc, alias_e, ident);
 
                 auto errors = gagError ? 0 : global.startGagging();

diff --git a/test/compilable/test5973.d b/test/compilable/test5973.d
@@ -0,0 +1,41 @@
+// https://issues.dlang.org/show_bug.cgi?id=5973
+
+class A { int a = 1; }
+class B { int b = 2; }
+class C : A
+{
+    B obj;
+    alias obj this;
+    this(){ obj = new B(); }
+}
+class X : C {}
+
+class D
+{
+    int i;
+}
+
+class E
+{
+    D x;
+    alias x this;
+}
+
+class F : E
+{
+    void test()
+    {
+        i = 5;
+    }
+}
+
+void main()
+{
+    auto c = new C();
+    assert(c.a == 1);   // lookup C -> A, OK
+    assert(c.b == 2);   // lookup C => B, OK
+
+    auto x = new X();
+    assert(x.a == 1);   // lookup X -> C -> A, OK
+    assert(x.b == 2);   // lookup X -> C => B, NG (Line 17)
+}