Merge: bugfix: is optional attributes was evaluated too much

`is optional` attribute must not be evaluated on the allocation, but only if `null` is given in the `new`.

Since the use of `is optional` did not spread, no one seems to have been bitten yet.

Pull-Request: #2053
Reviewed-by: Lucas Bajolet <[email protected]>

src/compiler/abstract_compiler.nit

@@ -3162,7 +3162,7 @@ redef class AAttrPropdef
 
 	fun init_expr(v: AbstractCompilerVisitor, recv: RuntimeVariable)
 	do
-		if has_value and not is_lazy and not n_expr isa ANullExpr then evaluate_expr(v, recv)
+		if has_value and not is_lazy and not is_optional and not n_expr isa ANullExpr then evaluate_expr(v, recv)
 	end
 
 	# Evaluate, store and return the default value of the attribute

src/interpreter/naive_interpreter.nit

@@ -1514,7 +1514,7 @@ redef class AAttrPropdef
 	# Evaluate and set the default value of the attribute in `recv`
 	private fun init_expr(v: NaiveInterpreter, recv: Instance)
 	do
-		if is_lazy then return
+		if is_lazy or is_optional then return
 		if has_value then
 			var f = v.new_frame(self, mreadpropdef.as(not null), [recv])
 			evaluate_expr(v, recv, f)

tests/base_is_optional.nit

@@ -0,0 +1,68 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import core::kernel
+
+fun foo(i: Int): Int
+do
+	'f'.output
+	i.output
+	return i
+end
+
+class A
+	# needed on the new
+	var i: Int
+
+	# initialized by the allocation
+	var j: Int = foo(2)
+
+	# optional in the new, default value evaluated if `null` is given
+	var k: Int = foo(3) is optional
+
+	# the `init` will initialize it
+	var l: Int is noautoinit
+	init do l = foo(4)
+
+	# initialized if needed on the first `read`
+	var m: Int = foo(5) is lazy
+
+	fun set
+	do
+		i = 10
+		j = 20
+		k = 30
+		l = 40
+		m = 50
+	end
+
+	fun test
+	do
+		#alt1#set
+		i.output
+		j.output
+		k.output
+		l.output
+		m.output
+		'\n'.output
+	end
+end
+
+var a
+a = new A(foo(100))
+a.test
+a = new A(foo(100), null)
+a.test
+a = new A(foo(100), foo(300))
+a.test

tests/sav/base_is_optional.res

@@ -0,0 +1,33 @@
+f2
+f100
+f3
+f4
+100
+2
+3
+4
+f5
+5
+
+f2
+f100
+f3
+f4
+100
+2
+3
+4
+f5
+5
+
+f2
+f100
+f300
+f4
+100
+2
+300
+4
+f5
+5
+

tests/sav/base_is_optional_alt1.res

@@ -0,0 +1,30 @@
+f2
+f100
+f3
+f4
+10
+20
+30
+40
+50
+
+f2
+f100
+f3
+f4
+10
+20
+30
+40
+50
+
+f2
+f100
+f300
+f4
+10
+20
+30
+40
+50
+