Narrow lvalue checking special case from arrays to array views

compiler/resolution/functionResolution.cpp

@@ -655,8 +655,14 @@ isLegalLvalueActualArg(ArgSymbol* formal, Expr* actual,
         sym->isParameter())
       actualConst = true;
 
-    bool actualExprTmp = sym->hasFlag(FLAG_EXPR_TEMP) &&
-                         !sym->type->symbol->hasFlag(FLAG_ARRAY);
+    bool actualExprTmp = sym->hasFlag(FLAG_EXPR_TEMP);
+
+    // don't emit lvalue errors for array slices
+    // (we can think of these as a special kind of reference)
+    if (isAliasingArrayType(sym->type)) {
+      actualExprTmp = false;
+    }
+
     TypeSymbol* formalTS = NULL;
     bool formalCopyMutates = false;
     if (formal) {

compiler/resolution/wrappers.cpp

@@ -2710,10 +2710,6 @@ static void initPromotionWrapper(PromotionInfo& promotion,
   retval->addFlag(FLAG_PROMOTION_WRAPPER);
   retval->addFlag(FLAG_FN_RETURNS_ITERATOR);
 
-  if (fn->hasFlag(FLAG_OPERATOR)) {
-    retval->addFlag(FLAG_OPERATOR);
-  }
-
   int i = 0;
   for_formals(formal, fn) {
 
@@ -3207,7 +3203,10 @@ static FnSymbol* buildEmptyWrapper(FnSymbol* fn) {
   if (fn->hasFlag(FLAG_METHOD_PRIMARY)) wrapper->addFlag(FLAG_METHOD_PRIMARY);
   if (fn->hasFlag(FLAG_ASSIGNOP))       wrapper->addFlag(FLAG_ASSIGNOP);
   if (fn->hasFlag(FLAG_LAST_RESORT))    wrapper->addFlag(FLAG_LAST_RESORT);
+  if (fn->hasFlag(FLAG_OPERATOR))       wrapper->addFlag(FLAG_OPERATOR);
 
+  if (   fn->hasFlag(FLAG_REF_TO_CONST_WHEN_CONST_THIS))
+    wrapper->addFlag(FLAG_REF_TO_CONST_WHEN_CONST_THIS);
   if (   fn->hasFlag(FLAG_VOID_NO_RETURN_VALUE))
     wrapper->addFlag(FLAG_VOID_NO_RETURN_VALUE);
   if (   fn->hasFlag(FLAG_FN_RETURNS_ITERATOR))

test/arrays/ferguson/choose-array/choose-array3-2.good

@@ -1,4 +1,2 @@
-1 1 1 1 1 1 1 1 1 1
-2 2 2 2 2 2 2 2 2 2
-8 2 2 2 2 2 2 2 2 2
-9 1 1 1 1 1 1 1 1 1
+choose-array3-2.chpl:24: error: non-lvalue actual is passed to 'ref' formal 'C' of updateAndPrint()
+choose-array3-2.chpl:24: error: non-lvalue actual is passed to 'ref' formal 'D' of updateAndPrint()

test/arrays/ferguson/if-expr/aif4-param.1-0.good

@@ -1,4 +1,3 @@
 1 0 0
-1 0 3
 1 0 0
 0 0 0

test/arrays/ferguson/if-expr/aif4-param.2-0.good

@@ -1,4 +1,3 @@
 2 0 0
-2 0 3
 0 0 0
 2 0 0

test/arrays/ferguson/if-expr/aif4-param.chpl

@@ -5,11 +5,9 @@
 
 config param param_useA = true;
 
-proc update(ref x)
+proc passArray(const ref x)
 {
   writeln(x);
-  x[3] = 3;
-  writeln(x);
 }
 
 
@@ -26,7 +24,7 @@ proc makeB() {
 }
 
 proc run() {
-  update( if param_useA then makeA() else makeB() );
+  passArray( if param_useA then makeA() else makeB() );
 
   writeln(A);
   writeln(B);

test/arrays/ferguson/if-expr/aif4.0-1.good

@@ -1,4 +1,3 @@
 1 0 0
-1 0 3
 1 0 0
 0 0 0

test/arrays/ferguson/if-expr/aif4.0-2.good

@@ -1,4 +1,3 @@
 2 0 0
-2 0 3
 0 0 0
 2 0 0

test/arrays/ferguson/if-expr/aif4.chpl

@@ -4,11 +4,9 @@
 
 config const useA = true;
 
-proc update(ref x)
+proc passArray(const ref x)
 {
   writeln(x);
-  x[3] = 3;
-  writeln(x);
 }
 
 
@@ -25,7 +23,7 @@ proc makeB() {
 }
 
 proc run() {
-  update( if useA then makeA() else makeB() );
+  passArray( if useA then makeA() else makeB() );
 
   writeln(A);
   writeln(B);

test/arrays/ferguson/semantic-examples/1.2-pass-returned-global.chpl

@@ -5,11 +5,11 @@ var globalArray: [1..2] R;
 proc returnGlobalArray() {
  return globalArray;
 }
-proc setToOne(ref A:[] R) {
-  A[1] = one;
+proc setToOne(const ref A:[] R) {
+  globalArray[1] = one;
+  writeln(A[1].x);
 }
 setToOne(returnGlobalArray());
-writeln(globalArray[1].x);
 
 // Does this program output 0 or 1?
 // In other words, does the act of returning globalArray

test/arrays/ferguson/semantic-examples/1.4-assign-callexpr-array.good

@@ -1,6 +1 @@
-globalArray is 0
-setting returnGlobalArray() = ArrTwo
-copy/assign from 0
-copy/assign from 2
-globalArray is now 0
-0
+1.4-assign-callexpr-array.chpl:13: error: illegal lvalue in assignment

test/arrays/ferguson/semantic-examples/2-pass-returned-global-const.chpl

@@ -5,11 +5,11 @@ var globalArray: [1..2] R;
 proc returnGlobalArray() const {
  return globalArray;
 }
-proc setToOne(ref A:[] R) {
-  A[1] = one;
+proc setToOne(const ref A:[] R) {
+  globalArray[1] = one;
+  writeln(A[1].x);
 }
 setToOne(returnGlobalArray());
-writeln(globalArray[1].x);
 
 // Does this program output 0 or 1?
 // In other words, does the act of returning globalArray

test/arrays/return/array-lvalue-error.chpl

@@ -0,0 +1,17 @@
+proc makeInputArray(n: int) {
+  var A:[1..n] int = 1..n;
+  return A;
+}
+
+proc mutateAndSum(ref A) {
+  for x in A {
+    x *= 2;
+  }
+  return + reduce A;
+}
+
+var A = makeInputArray(1000);
+A[1..10] = 4; // this should not be an error
+
+var sum = mutateAndSum(makeInputArray(1000)); // this should be an error
+writeln(sum);

test/arrays/return/array-lvalue-error.good

@@ -0,0 +1 @@
+array-lvalue-error.chpl:16: error: non-lvalue actual is passed to 'ref' formal 'A' of mutateAndSum()

test/users/thom/arrArg-fromFunction.good

@@ -1 +1,2 @@
-[Design] What should be the result?
+arrArg-fromFunction.chpl:17: error: non-lvalue actual is passed to 'ref' formal 'X' of writeArrRef()
+arrArg-fromFunction.chpl:19: error: non-lvalue actual is passed to 'ref' formal 'X' of writeArrRef()