Attempt to resolve issue #16275

So far, only improves the array parts.

compiler/resolution/functionResolution.cpp

@@ -420,6 +420,10 @@ Type* getCopyTypeDuringResolution(Type* t) {
 
     FnSymbol* fn = getInitCopyDuringResolution(at);
     INT_ASSERT(fn);
+
+    if (fn->retType == t)
+      INT_FATAL("Expected different return type for this initCopy");
+
     return fn->retType;
   }
 
@@ -6767,6 +6771,11 @@ void resolveInitVar(CallExpr* call) {
       resolveMove(call);
     }
 
+    if (isAliasingArray(srcExpr->getValType()) || initCopyIter)
+      if (FnSymbol* initCopyFn = initCopy->resolvedFunction())
+        if (initCopyFn->retType == srcExpr->getValType())
+          INT_FATAL("Expected different return type for this initCopy");
+
   } else if (isRecord(targetType->getValType())) {
     AggregateType* at = toAggregateType(targetType->getValType());
 

modules/internal/ChapelArray.chpl

@@ -4381,9 +4381,27 @@ module ChapelArray {
 
   pragma "init copy fn"
   proc chpl__initCopy(const ref rhs: []) {
-    pragma "no copy"
-    var lhs = chpl__coerceCopy(rhs.type, rhs);
-    return lhs;
+
+    // Reindex and rank change domains should use a non-view domain
+    // when creating the new array. This is not a problem for slices
+    // because they already use a non-view domain.
+    if rhs._value.isRankChangeArrayView() {
+      type t = chpl__buildArrayRuntimeType(_getDomain(rhs.domain.upDom),
+                                           rhs.eltType);
+      pragma "no copy"
+      var lhs = chpl__coerceCopy(t, rhs);
+      return lhs;
+    } else if rhs._value.isReindexArrayView() {
+      type t = chpl__buildArrayRuntimeType(_getDomain(rhs.domain.updom),
+                                           rhs.eltType);
+      pragma "no copy"
+      var lhs = chpl__coerceCopy(t, rhs);
+      return lhs;
+    } else {
+      pragma "no copy"
+      var lhs = chpl__coerceCopy(rhs.type, rhs);
+      return lhs;
+    }
   }
 
   pragma "auto copy fn" proc chpl__autoCopy(x: []) {
@@ -4524,7 +4542,6 @@ module ChapelArray {
     return lhs;
   }
 
-
   pragma "find user line"
   pragma "coerce fn"
   proc chpl__coerceCopy(type dstType:_array, rhs:_array) {

test/arrays/ferguson/views-and-copying.chpl

@@ -0,0 +1,63 @@
+proc returnIt(arg) { return arg; }
+
+proc main() {
+  var A: [1..2] real;
+  var AA: [1..2, 1..2] real;
+
+  {
+    writeln();
+    writeln("slice");
+    const ref rB = A[1..1];
+    writeln("to const ref is view:         ", rB.isSliceArrayView());
+
+    var B = A[1..1];
+    writeln("to var is view:               ", B.isSliceArrayView());
+
+    const ref rReturned = returnIt(A[1..1]);
+    writeln("returned is view:             ", rReturned.isSliceArrayView());
+
+    const ref rD = A[1..1].domain;
+    writeln(".domain to const ref is view: ", rD.isSliceDomainView());
+
+    var D = A[1..1].domain;
+    writeln(".domain to var is view:       ", D.isSliceDomainView());
+  }
+
+  {
+    writeln();
+    writeln("reindex");
+    const ref rB = A.reindex(3..4);
+    writeln("to const ref is view:         ", rB.isReindexArrayView());
+
+    var B = A.reindex(3..4);
+    writeln("to var is view:               ", B.isReindexArrayView());
+
+    const ref rReturned = returnIt(A.reindex(3..4));
+    writeln("returned is view:             ", rReturned.isReindexArrayView());
+
+    const ref rD = A.reindex(3..4).domain;
+    writeln(".domain to const ref is view: ", rD.isReindexDomainView());
+
+    var D = A.reindex(3..4).domain;
+    writeln(".domain to var is view:       ", D.isReindexDomainView());
+  }
+
+  {
+    writeln();
+    writeln("rank change");
+    const ref rB = AA[1, ..];
+    writeln("to const ref is view:         ", rB.isRankChangeArrayView());
+
+    var B = AA[1, ..];
+    writeln("to var is view:               ", B.isRankChangeArrayView());
+
+    const ref rReturned = returnIt(AA[1, ..]);
+    writeln("returned is view:             ", rReturned.isRankChangeArrayView());
+
+    const ref rD = AA[1, ..].domain;
+    writeln(".domain to const ref is view: ", rD.isRankChangeDomainView());
+
+    var D = AA[1, ..].domain;
+    writeln(".domain to var is view:       ", D.isRankChangeDomainView());
+  }
+}

test/arrays/ferguson/views-and-copying.good

@@ -0,0 +1,21 @@
+
+slice
+to const ref is view:         true
+to var is view:               false
+returned is view:             false
+.domain to const ref is view: false
+.domain to var is view:       false
+
+reindex
+to const ref is view:         true
+to var is view:               false
+returned is view:             false
+.domain to const ref is view: true
+.domain to var is view:       true
+
+rank change
+to const ref is view:         true
+to var is view:               false
+returned is view:             false
+.domain to const ref is view: true
+.domain to var is view:       true