function/stdlib: Fix setproduct bug with unknowns

cty/function/stdlib/collection.go

@@ -948,12 +948,16 @@ var SetProductFunc = function.New(&function.Spec{
 		var retMarks cty.ValueMarks
 
 		total := 1
+		var hasUnknownLength bool
 		for _, arg := range args {
 			arg, marks := arg.Unmark()
 			retMarks = cty.NewValueMarks(retMarks, marks)
 
+			// Continue processing after we find an argument with unknown
+			// length to ensure that we cover all the marks
 			if !arg.Length().IsKnown() {
-				return cty.UnknownVal(retType).Mark(marks), nil
+				hasUnknownLength = true
+				continue
 			}
 
 			// Because of our type checking function, we are guaranteed that
@@ -962,6 +966,10 @@ var SetProductFunc = function.New(&function.Spec{
 			total *= arg.LengthInt()
 		}
 
+		if hasUnknownLength {
+			return cty.UnknownVal(retType).WithMarks(retMarks), nil
+		}
+
 		if total == 0 {
 			// If any of the arguments was an empty collection then our result
 			// is also an empty collection, which we'll short-circuit here.

cty/function/stdlib/collection_test.go

@@ -2324,6 +2324,36 @@ func TestSetproduct(t *testing.T) {
 			}).Mark("b"),
 			``,
 		},
+		{
+			// Empty lists with marks should propagate the marks
+			[]cty.Value{
+				cty.ListValEmpty(cty.String).Mark("a"),
+				cty.ListValEmpty(cty.Bool).Mark("b"),
+			},
+			cty.ListValEmpty(cty.Tuple([]cty.Type{cty.String, cty.Bool})).WithMarks(cty.NewValueMarks("a", "b")),
+			``,
+		},
+		{
+			// Empty sets with marks should propagate the marks
+			[]cty.Value{
+				cty.SetValEmpty(cty.String).Mark("a"),
+				cty.SetValEmpty(cty.Bool).Mark("b"),
+			},
+			cty.SetValEmpty(cty.Tuple([]cty.Type{cty.String, cty.Bool})).WithMarks(cty.NewValueMarks("a", "b")),
+			``,
+		},
+		{
+			// Arguments which are sets with partially unknown values results
+			// in unknown length (since the unknown values may already be
+			// present in the set). This gives an unknown result preserving all
+			// marks
+			[]cty.Value{
+				cty.SetVal([]cty.Value{cty.StringVal("x"), cty.UnknownVal(cty.String)}).Mark("a"),
+				cty.SetVal([]cty.Value{cty.True, cty.False}).Mark("b"),
+			},
+			cty.UnknownVal(cty.Set(cty.Tuple([]cty.Type{cty.String, cty.Bool}))).WithMarks(cty.NewValueMarks("a", "b")),
+			``,
+		},
 	}
 
 	for _, test := range tests {