Merge pull request #247 from ibuclaw/bug242

Bug 242: Do constant propagation of enums when frontend doesn't.

gcc/d/ChangeLog

@@ -1,3 +1,10 @@
+2016-10-03  Iain Buclaw  <ibuclaw@gdcproject.org>
+
+	* d-objfile.cc (VarDeclaration::toObjFile): Always generate
+	DECL_INITIAL for all kinds of var decls.
+	* d-codegen.cc (build_address): Use the DECL_INITIAL directly if
+	taking the address of a CONST_DECL.
+
 2016-09-26  Johannes Pfau  <johannespfau@gmail.com>
 
 	* d-objfile.cc (d_finish_function): Handle template mixins (issue 231).

gcc/d/d-codegen.cc

@@ -1734,9 +1734,13 @@ build_address(tree exp)
   else
     ptrtype = build_pointer_type(type);
 
-  // Maybe rewrite: (e1, e2) => (e1, &e2)
+  // Maybe rewrite: &(e1, e2) => (e1, &e2)
   tree init = stabilize_expr(&exp);
 
+  // Can't take the address of a manifest constant, instead use its value.
+  if (TREE_CODE (exp) == CONST_DECL)
+    exp = DECL_INITIAL (exp);
+
   d_mark_addressable(exp);
   exp = build_fold_addr_expr_with_type_loc(input_location, exp, ptrtype);
 

gcc/d/d-objfile.cc

@@ -826,19 +826,23 @@ VarDeclaration::toObjFile()
       if (isInstantiated())
 	return;
 
-      // CONST_DECL was initially intended for enumerals and may
-      // be used for scalars in general but not for aggregates.
-      if (!type->isscalar())
-	return;
-
       tree decl = toSymbol()->Stree;
       gcc_assert (init && !init->isVoidInitializer());
-
       Expression *ie = init->toExpression();
-      DECL_INITIAL (decl) = build_expr(ie, true);
 
-      d_pushdecl (decl);
-      rest_of_decl_compilation (decl, 1, 0);
+      // CONST_DECL was initially intended for enumerals and may be used for
+      // scalars in general, but not for aggregates.  Here a non-constant value
+      // is generated anyway so as the CONST_DECL only serves as a placeholder
+      // for the value, however the DECL itself should never be referenced in
+      // any generated code, or passed to the backend.
+      if (!type->isscalar())
+	DECL_INITIAL (decl) = build_expr(ie, false);
+      else
+	{
+	  DECL_INITIAL (decl) = build_expr(ie, true);
+	  d_pushdecl (decl);
+	  rest_of_decl_compilation (decl, 1, 0);
+	}
     }
   else if (isDataseg() && !(storage_class & STCextern))
     {

gcc/testsuite/gdc.test/compilable/gdc242.d

@@ -0,0 +1,23 @@
+// PERMUTE_ARGS:
+
+struct S242a
+{
+    enum M = S242a();
+    void iter() { }
+}
+
+void test242a()
+{
+    return S242a.M.iter;
+}
+
+struct S242b
+{
+    enum M = S242b();
+    void iter() { }
+}
+
+void test242b()
+{
+    S242b.M.iter;
+}

gcc/testsuite/gdc.test/runnable/gdc.d

@@ -1031,6 +1031,32 @@ void test210()
 
 /******************************************/
 
+// Bug 242
+
+struct S242
+{
+    enum M = S242();
+    int a = 42;
+
+    auto iter()
+    {
+        this.a = 24;
+        return this;
+    }
+}
+
+S242 test242a()
+{
+    return S242.M.iter;
+}
+
+void test242()
+{
+    assert(test242a() == S242(24));
+}
+
+/******************************************/
+
 void main()
 {
     test2();