Fix issue 20700 - Fwd refs leads to extern(C++, class|struct) being i…

…gnored On the long run, it looks like we should just move the setScope to AttribDeclaration, but this is a simple bugfix to target stable.
dlang · Apr 2, 2020 · c533ad1 · c533ad1
1 parent e34203a
commit c533ad1
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Showing 4 changed files with 29 additions and 5 deletions.
diff --git a/src/dmd/attrib.d b/src/dmd/attrib.d
@@ -435,6 +435,13 @@ extern (C++) final class CPPMangleDeclaration : AttribDeclaration
             sc.aligndecl, sc.inlining);
     }
 
+    override void setScope(Scope* sc)
+    {
+        if (decl)
+            Dsymbol.setScope(sc); // for forward reference
+        return AttribDeclaration.setScope(sc);
+    }
+
     override const(char)* toChars() const
     {
         return toString().ptr;

diff --git a/src/dmd/attrib.h b/src/dmd/attrib.h
@@ -88,6 +88,7 @@ class CPPMangleDeclaration : public AttribDeclaration
 
     Dsymbol *syntaxCopy(Dsymbol *s);
     Scope *newScope(Scope *sc);
+    void setScope(Scope *sc);
     const char *toChars() const;
     void accept(Visitor *v) { v->visit(this); }
 };

diff --git a/src/dmd/typesem.d b/src/dmd/typesem.d
@@ -1810,13 +1810,16 @@ extern(C++) Type typeSemantic(Type t, const ref Loc loc, Scope* sc)
     Type visitStruct(TypeStruct mtype)
     {
         //printf("TypeStruct::semantic('%s')\n", mtype.toChars());
+        // If this is called via a forward reference,
+        // use the dsymbol's scope so that `extern(C++ class|struct)` applies
+        // https://issues.dlang.org/show_bug.cgi?id=20700
+        auto cppmangle = (mtype.sym && mtype.sym._scope) ?
+            mtype.sym._scope.cppmangle : sc.cppmangle;
+
         if (mtype.deco)
         {
-            if (sc && sc.cppmangle != CPPMANGLE.def)
-            {
-                if (mtype.cppmangle == CPPMANGLE.def)
-                    mtype.cppmangle = sc.cppmangle;
-            }
+            assert(cppmangle == CPPMANGLE.def ||
+                   cppmangle == mtype.cppmangle);
             return mtype;
         }
 

diff --git a/test/compilable/cppmangle.d b/test/compilable/cppmangle.d
@@ -1251,3 +1251,16 @@ extern(C++, `bar`)
 {
     void func19542(T)();
 }
+
+// https://issues.dlang.org/show_bug.cgi?id=20700
+version (Windows)
+extern(C++)
+{
+    void test20700_1(const ref Struct20700);
+    extern(C++, class) struct Struct20700 {}
+    void test20700_2(const ref Struct20700);
+
+    // Note: Needs to be `BV` (`class`), not `BU` (`struct`)
+    static assert(test20700_1.mangleof == `?test20700_1@@YAXABVStruct20700@@@Z`);
+    static assert(test20700_2.mangleof == `?test20700_2@@YAXABVStruct20700@@@Z`);
+}