Make 'Unreachable statement' a warning

src/semantize/flow.nit

@@ -305,7 +305,7 @@ redef class ABlockExpr
 				v.enter_visit(e)
 			else if not v.current_flow_context.is_already_unreachable then
 				v.current_flow_context.is_already_unreachable = true
-				v.toolcontext.error(e.hot_location, "Error: unreachable statement.")
+				v.toolcontext.warning(e.hot_location, "unreachable", "Warning: unreachable statement.")
 			end
 		end
 	end

src/semantize/local_var_init.nit

@@ -59,17 +59,17 @@ private class LocalVarInitVisitor
 		assert variable != null
 		if not maybe_unset_vars.has(variable) then return
 
-		var flow = node.after_flow_context.as(not null)
-		flow.set_vars.add(variable)
+		var flow = node.after_flow_context
+		if flow != null then flow.set_vars.add(variable)
 	end
 
 	fun check_is_set(node: AExpr, variable: nullable Variable)
 	do
 		assert variable != null
 		if not maybe_unset_vars.has(variable) then return
 
-		var flow = node.after_flow_context.as(not null)
-		if not flow.is_variable_set(variable) then
+		var flow = node.after_flow_context
+		if flow != null and not flow.is_variable_set(variable) then
 			self.toolcontext.error(node.hot_location, "Error: possibly unset variable `{variable}`.")
 			# Remove the variable to avoid repeating errors
 			self.maybe_unset_vars.remove(variable)

src/semantize/typing.nit

@@ -634,9 +634,7 @@ private class TypeVisitor
 	fun set_variable(node: AExpr, variable: Variable, mtype: nullable MType)
 	do
 		var flow = node.after_flow_context
-		assert flow != null
-
-		flow.set_var(self, variable, mtype)
+		if flow != null then flow.set_var(self, variable, mtype)
 	end
 
 	# Find the exact representable most specific common super-type in `col`.

tests/base_control_flow3.nit

@@ -0,0 +1,49 @@
+# 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 kernel
+
+var a
+a = null
+a = 1
+
+a.output
+return
+# Below this line the code is unreachable
+
+var b
+b = null
+b = 1
+a.output
+b.output
+a = b
+b = a
+
+if a == b then
+	a = b
+	b = a
+else
+	a = null
+	b = null
+end
+a.output
+b.output
+var c = a.as(not null)
+var d = b.as(Int)
+var e
+e.output
+
+#alt1#(b+1).output # Error
+b = 1
+#alt1#(b+1).output # Still error

tests/sav/base_control_flow2_alt1.res

@@ -1,4 +1,4 @@
-alt/base_control_flow2_alt1.nit:24,2: Error: unreachable statement.
+alt/base_control_flow2_alt1.nit:24,2: Warning: unreachable statement.
 alt/base_control_flow2_alt1.nit:21,1--25,3: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt1.nit:39,1--43,3: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt1.nit:47,2--51,4: Warning: use `loop` instead of `while true do`.

tests/sav/base_control_flow2_alt2.res

@@ -1,5 +1,5 @@
 alt/base_control_flow2_alt2.nit:21,1--25,3: Warning: use `loop` instead of `while true do`.
-alt/base_control_flow2_alt2.nit:30,2: Error: unreachable statement.
+alt/base_control_flow2_alt2.nit:30,2: Warning: unreachable statement.
 alt/base_control_flow2_alt2.nit:39,1--43,3: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt2.nit:47,2--51,4: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt2.nit:45,1--55,3: Warning: use `loop` instead of `while true do`.

tests/sav/base_control_flow2_alt3.res

@@ -1,5 +1,5 @@
 alt/base_control_flow2_alt3.nit:21,1--25,3: Warning: use `loop` instead of `while true do`.
-alt/base_control_flow2_alt3.nit:42,2: Error: unreachable statement.
+alt/base_control_flow2_alt3.nit:42,2: Warning: unreachable statement.
 alt/base_control_flow2_alt3.nit:39,1--43,3: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt3.nit:47,2--51,4: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt3.nit:45,1--55,3: Warning: use `loop` instead of `while true do`.

tests/sav/base_control_flow2_alt4.res

@@ -1,5 +1,5 @@
 alt/base_control_flow2_alt4.nit:21,1--25,3: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt4.nit:39,1--43,3: Warning: use `loop` instead of `while true do`.
-alt/base_control_flow2_alt4.nit:50,3: Error: unreachable statement.
+alt/base_control_flow2_alt4.nit:50,3: Warning: unreachable statement.
 alt/base_control_flow2_alt4.nit:47,2--51,4: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt4.nit:45,1--55,3: Warning: use `loop` instead of `while true do`.

tests/sav/base_control_flow2_alt5.res

@@ -1,5 +1,5 @@
 alt/base_control_flow2_alt5.nit:21,1--25,3: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt5.nit:39,1--43,3: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt5.nit:47,2--51,4: Warning: use `loop` instead of `while true do`.
-alt/base_control_flow2_alt5.nit:54,2: Error: unreachable statement.
+alt/base_control_flow2_alt5.nit:54,2: Warning: unreachable statement.
 alt/base_control_flow2_alt5.nit:45,1--55,3: Warning: use `loop` instead of `while true do`.

tests/sav/base_control_flow2_alt6.res

@@ -2,4 +2,4 @@ alt/base_control_flow2_alt6.nit:21,1--25,3: Warning: use `loop` instead of `whil
 alt/base_control_flow2_alt6.nit:39,1--43,3: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt6.nit:47,2--51,4: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt6.nit:45,1--55,3: Warning: use `loop` instead of `while true do`.
-alt/base_control_flow2_alt6.nit:60,2: Error: unreachable statement.
+alt/base_control_flow2_alt6.nit:60,2: Warning: unreachable statement.

tests/sav/base_control_flow2_alt7.res

@@ -2,4 +2,4 @@ alt/base_control_flow2_alt7.nit:21,1--25,3: Warning: use `loop` instead of `whil
 alt/base_control_flow2_alt7.nit:39,1--43,3: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt7.nit:47,2--51,4: Warning: use `loop` instead of `while true do`.
 alt/base_control_flow2_alt7.nit:45,1--55,3: Warning: use `loop` instead of `while true do`.
-alt/base_control_flow2_alt7.nit:67,2: Error: unreachable statement.
+alt/base_control_flow2_alt7.nit:67,2: Warning: unreachable statement.

tests/sav/base_control_flow3.res

@@ -0,0 +1,2 @@
+base_control_flow3.nit:25,1--5: Warning: unreachable statement.
+1

tests/sav/base_control_flow3_alt1.res

@@ -0,0 +1,3 @@
+alt/base_control_flow3_alt1.nit:25,1--5: Warning: unreachable statement.
+alt/base_control_flow3_alt1.nit:47,3: Error: method `+` does not exists in `nullable Object`.
+alt/base_control_flow3_alt1.nit:49,3: Error: method `+` does not exists in `nullable Object`.

tests/sav/base_control_flow_alt2.res

@@ -1 +1 @@
-alt/base_control_flow_alt2.nit:23,2: Error: unreachable statement.
+alt/base_control_flow_alt2.nit:23,2: Warning: unreachable statement.

tests/sav/base_control_flow_alt3.res

@@ -1 +1 @@
-alt/base_control_flow_alt3.nit:54,2: Error: unreachable statement.
+alt/base_control_flow_alt3.nit:54,2: Warning: unreachable statement.

tests/sav/nit_args9.res

@@ -1,9 +1,6 @@
 test_keep_going.nit:15,11--14: Error: class `Fail` not found in module `test_keep_going`.
 	fun plop: Fail
 	          ^
-test_keep_going.nit:40,2--11: Error: unreachable statement.
-		999.output
-		^
 test_keep_going.nit:26,2--5: Error: method or variable `fail` unknown in `Sys`.
 		fail
 		^
@@ -13,10 +10,13 @@
 test_keep_going.nit:35,5: Type Error: expected `Bool`, got `Int`.
 		if 1 then abort
 		   ^
+test_keep_going.nit:40,2--11: Warning: unreachable statement. (unreachable)
+		999.output
+		^
 test_keep_going.nit:44,18--21: Error: method `fail` does not exists in `Sys`.
 		var a = new Sys.fail
 		                ^
-Errors: 6. Warnings: 0.
+Errors: 5. Warnings: 1.
 1
 2
 3

tests/sav/nitc_args12.res

@@ -1,9 +1,6 @@
 test_keep_going.nit:15,11--14: Error: class `Fail` not found in module `test_keep_going`.
 	fun plop: Fail
 	          ^
-test_keep_going.nit:40,2--11: Error: unreachable statement.
-		999.output
-		^
 test_keep_going.nit:26,2--5: Error: method or variable `fail` unknown in `Sys`.
 		fail
 		^
@@ -13,10 +10,13 @@
 test_keep_going.nit:35,5: Type Error: expected `Bool`, got `Int`.
 		if 1 then abort
 		   ^
+test_keep_going.nit:40,2--11: Warning: unreachable statement. (unreachable)
+		999.output
+		^
 test_keep_going.nit:44,18--21: Error: method `fail` does not exists in `Sys`.
 		var a = new Sys.fail
 		                ^
-Errors: 6. Warnings: 0.
+Errors: 5. Warnings: 1.
 1
 2
 3

tests/sav/syntax_lambda.res

@@ -1 +1,17 @@
-syntax_lambda.nit:36,1--28: Error: unreachable statement.
+syntax_lambda.nit:24,9--18: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:26,9--22: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:28,11--24: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:31,9--33,7: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:36,9--28: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:36,1--28: Warning: unreachable statement.
+syntax_lambda.nit:37,10--26: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:39,9--30: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:41,9--48: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:43,10--29: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:45,5--18: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:46,5--18: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:49,1--51,8: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:55,2--15: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:56,1--14: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:58,9--60,10: no implemented accept_typing for ALambdaExpr
+syntax_lambda.nit:64,1--32: no implemented accept_typing for ALambdaExpr