src/func.d

@@ -4435,20 +4435,50 @@ public:
         /* See if it's the default constructor
          * But, template constructor should not become a default constructor.
          */
-        if (ad && tf.varargs == 0 && Parameter.dim(tf.parameters) == 0 && (!parent.isTemplateInstance() || parent.isTemplateMixin()))
+        if (ad && (!parent.isTemplateInstance() || parent.isTemplateMixin()))
         {
+            size_t dim = Parameter.dim(tf.parameters);
             StructDeclaration sd = ad.isStructDeclaration();
             if (sd)
             {
-                if (fbody || !(storage_class & STCdisable))
+                bool allDefaultedParams = (dim == 0) && tf.varargs == 1;  // c-style: foo(...)
+                bool isDefCtor = dim == 0;
+
+                for (size_t i = 0; i < dim; i++)
                 {
-                    error("default constructor for structs only allowed with @disable and no body");
-                    storage_class |= STCdisable;
-                    fbody = null;
+                    auto arg = Parameter.getNth(tf.parameters, i);
+
+                    // note: D-style variadic arguments allowed as a special-case (tf.varargs == 2)
+                    if (i + 1 == dim && arg.defaultArg)
+                    {
+                        isDefCtor = true;
+                        allDefaultedParams = true;
+                    }
+                    else
+                    {
+                        break;
+                    }
+                }
+
+                if (isDefCtor)
+                {
+                    if (allDefaultedParams)  // only warn for now
+                    {
+                        warning(loc, "%s %s default constructor for structs "
+                            "only allowed with @disable, no body, and no "
+                            "parameters", kind(), toPrettyChars());
+                    }
+                    else if (fbody || !(storage_class & STCdisable) || dim)
+                    {
+                        error("default constructor for structs only allowed "
+                            "with @disable, no body, and no parameters");
+                        storage_class |= STCdisable;
+                        fbody = null;
+                    }
+                    sd.noDefaultCtor = true;
                 }
-                sd.noDefaultCtor = true;
             }
-            else
+            else if (dim == 0 && tf.varargs == 0)
             {
                 ad.defaultCtor = this;
             }

test/compilable/compile1.d

@@ -929,3 +929,11 @@ void test15163()
     auto arr = [[0]];
     func15164(arr[0])();
 }
+
+/**************************************************
+    3438
+**************************************************/
+import core.vararg;
+struct S3438_1 { this(int x, int y = 1) { } }
+struct S3438_2 { this(int x, ...) { } }
+struct S3438_3 { this(int x, int[] arr...) { } }

test/compilable/ddoc7795.d

@@ -11,7 +11,7 @@ struct TimeValue {
 ///
 struct DateTime {
     ///
-    this(TimeValue t = TimeValue(0, 0)) {}
+    this(int x, TimeValue t = TimeValue(0, 0)) {}
 }
 
 void main() { }

test/compilable/extra-files/ddoc7795.html

@@ -7,7 +7,7 @@ <h1>ddoc7795</h1>
 <dl><dt><big><a name="DateTime"></a>struct <u>DateTime</u>;
 </big></dt>
 <dd><br><br>
-<dl><dt><big><a name="DateTime.this"></a>this(TimeValue <i>t</i> = TimeValue(0, 0));
+<dl><dt><big><a name="DateTime.this"></a>this(int <i>x</i>, TimeValue <i>t</i> = TimeValue(0, 0));
 </big></dt>
 <dd><br><br>
 </dd>

test/compilable/interpret3.d

@@ -6708,7 +6708,7 @@ static assert(test11510());
 
 struct MultiArray11534
 {
-    this(size_t[] sizes...)
+    void set(size_t[] sizes...)
     {
         storage = new size_t[5];
     }
@@ -6721,7 +6721,8 @@ struct MultiArray11534
 }
 
 enum test11534 = () {
-    auto m = MultiArray11534(3,2,1);
+    auto m = MultiArray11534();
+    m.set(3,2,1);
     auto start = m.raw_ptr;   //this trigger the bug
     //auto start = m.storage.ptr + 1; //this obviously works
     return 0;

test/fail_compilation/diag3438.d

@@ -0,0 +1,20 @@
+// REQUIRED_ARGS: -w
+/*
+TEST_OUTPUT:
+---
+fail_compilation/diag3438.d(15): Warning: constructor diag3438.F1.this default constructor for structs only allowed with @disable, no body, and no parameters
+fail_compilation/diag3438.d(16): Warning: constructor diag3438.F2.this default constructor for structs only allowed with @disable, no body, and no parameters
+fail_compilation/diag3438.d(17): Warning: constructor diag3438.F3.this default constructor for structs only allowed with @disable, no body, and no parameters
+fail_compilation/diag3438.d(19): Warning: constructor diag3438.F5.this default constructor for structs only allowed with @disable, no body, and no parameters
+fail_compilation/diag3438.d(20): Warning: constructor diag3438.F6.this default constructor for structs only allowed with @disable, no body, and no parameters
+---
+*/
+
+import core.vararg;
+
+struct F1 { this(int x = 1) { } }
+struct F2 { this(int x = 1, ...) { } }
+struct F3 { this(...) { } }
+struct F4 { this(int[] x...) { } }  // ok
+struct F5 { @disable this(int x = 1); }
+struct F6 { @disable this(int x = 1) { } }

test/fail_compilation/fail250.d

@@ -1,7 +1,7 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/fail250.d(10): Error: constructor fail250.A.this default constructor for structs only allowed with @disable and no body
+fail_compilation/fail250.d(10): Error: constructor fail250.A.this default constructor for structs only allowed with @disable, no body, and no parameters
 ---
 */
 

test/fail_compilation/ice14146.d

@@ -1,7 +1,7 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/ice14146.d(15): Error: constructor ice14146.Array.this default constructor for structs only allowed with @disable and no body
+fail_compilation/ice14146.d(15): Error: constructor ice14146.Array.this default constructor for structs only allowed with @disable, no body, and no parameters
 ---
 */