Add feature flag and test cases for loop CFA

Analysis/src/TypeInfer.cpp

@@ -40,6 +40,7 @@ LUAU_FASTFLAGVARIABLE(LuauFixCyclicModuleExports, false)
 LUAU_FASTFLAG(LuauOccursIsntAlwaysFailure)
 LUAU_FASTFLAGVARIABLE(LuauTypecheckTypeguards, false)
 LUAU_FASTFLAGVARIABLE(LuauTinyControlFlowAnalysis, false)
+LUAU_FASTFLAGVARIABLE(LuauLoopControlFlowAnalysis, false)
 LUAU_FASTFLAGVARIABLE(LuauAlwaysCommitInferencesOfFunctionCalls, false)
 LUAU_FASTFLAG(LuauParseDeclareClassIndexer)
 LUAU_FASTFLAGVARIABLE(LuauIndexTableIntersectionStringExpr, false)

tests/TypeInfer.cfa.test.cpp

@@ -26,6 +26,46 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return")
     CHECK_EQ("string", toString(requireTypeAtPosition({6, 24})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_break")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}})
+            for _, record in x do
+                if not record.value then
+                    break
+                end
+
+                local foo = record.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({7, 34})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_continue")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}})
+            for _, record in x do
+                if not record.value then
+                    continue
+                end
+
+                local foo = record.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({7, 38})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return_elif_not_y_return")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};
@@ -48,6 +88,56 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return_elif_not_y_return")
     CHECK_EQ("string", toString(requireTypeAtPosition({9, 24})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_break_elif_not_y_break")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                if not recordX.value then
+                    break
+                elseif not recordY.value then
+                    break
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({10, 38})));
+    CHECK_EQ("string", toString(requireTypeAtPosition({11, 38})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_continue_elif_not_y_continue")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                if not recordX.value then
+                    continue
+                elseif not recordY.value then
+                    continue
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({10, 38})));
+    CHECK_EQ("string", toString(requireTypeAtPosition({11, 38})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return_elif_rand_return_elif_not_y_return")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};
@@ -72,6 +162,60 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return_elif_rand_return_elif_not_y_
     CHECK_EQ("string", toString(requireTypeAtPosition({11, 24})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_break_elif_rand_break_elif_not_y_break")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                if not recordX.value then
+                    break
+                elseif math.random() > 0.5 then
+                    break
+                elseif not recordY.value then
+                    break
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({12, 38})));
+    CHECK_EQ("string", toString(requireTypeAtPosition({13, 38})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_continue_elif_rand_continue_elif_not_y_continue")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                if not recordX.value then
+                    continue
+                elseif math.random() > 0.5 then
+                    continue
+                elseif not recordY.value then
+                    continue
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({12, 38})));
+    CHECK_EQ("string", toString(requireTypeAtPosition({13, 38})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return_elif_not_rand_return_elif_not_y_fallthrough")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};
@@ -96,6 +240,60 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return_elif_not_rand_return_elif_no
     CHECK_EQ("string?", toString(requireTypeAtPosition({11, 24})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_break_elif_rand_break_elif_not_y_fallthrough")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                if not recordX.value then
+                    break
+                elseif math.random() > 0.5 then
+                    break
+                elseif not recordY.value then
+                    
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({12, 38})));
+    CHECK_EQ("string?", toString(requireTypeAtPosition({13, 38})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_continue_elif_rand_continue_elif_not_y_fallthrough")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                if not recordX.value then
+                    continue
+                elseif math.random() > 0.5 then
+                    continue
+                elseif not recordY.value then
+                    
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({12, 38})));
+    CHECK_EQ("string?", toString(requireTypeAtPosition({13, 38})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return_elif_not_y_fallthrough_elif_not_z_return")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};
@@ -122,6 +320,66 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return_elif_not_y_fallthrough_elif_
     CHECK_EQ("string?", toString(requireTypeAtPosition({12, 24})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_break_elif_not_y_fallthrough_elif_not_z_break")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}}, z: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                local recordZ = y[i]
+                if not recordX.value then
+                    break
+                elseif not recordY.value then
+                    
+                elseif not recordZ.value then
+                    break
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+                local baz = recordZ.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({13, 38})));
+    CHECK_EQ("string?", toString(requireTypeAtPosition({14, 38})));
+    CHECK_EQ("string?", toString(requireTypeAtPosition({15, 38})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_continue_elif_not_y_fallthrough_elif_not_z_continue")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}}, z: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                local recordZ = y[i]
+                if not recordX.value then
+                    continue
+                elseif not recordY.value then
+                    
+                elseif not recordZ.value then
+                    continue
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+                local baz = recordZ.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({13, 38})));
+    CHECK_EQ("string?", toString(requireTypeAtPosition({14, 38})));
+    CHECK_EQ("string?", toString(requireTypeAtPosition({15, 38})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "do_if_not_x_return")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};
@@ -142,6 +400,50 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "do_if_not_x_return")
     CHECK_EQ("string", toString(requireTypeAtPosition({8, 24})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "for_record_do_if_not_x_break")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}})
+            for _, record in x do
+                do
+                    if not record.value then
+                        break
+                    end
+                end
+
+                local foo = record.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({9, 38})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "for_record_do_if_not_x_continue")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}})
+            for _, record in x do
+                do
+                    if not record.value then
+                        continue
+                    end
+                end
+
+                local foo = record.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({9, 38})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "early_return_in_a_loop_which_isnt_guaranteed_to_run_first")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};
@@ -271,6 +573,60 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_return_if_not_y_return")
     CHECK_EQ("string", toString(requireTypeAtPosition({11, 24})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_break_if_not_y_break")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                if not recordX.value then
+                    break
+                end
+
+                if not recordY.value then
+                    break
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({12, 38})));
+    CHECK_EQ("string", toString(requireTypeAtPosition({13, 38})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "if_not_x_continue_if_not_y_continue")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}}, y: {{value: string?}})
+            for i, recordX in x do
+                local recordY = y[i]
+                if not recordX.value then
+                    continue
+                end
+
+                if not recordY.value then
+                    continue
+                end
+
+                local foo = recordX.value
+                local bar = recordY.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+    CHECK_EQ("string", toString(requireTypeAtPosition({12, 38})));
+    CHECK_EQ("string", toString(requireTypeAtPosition({13, 38})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_does_not_leak_out")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};
@@ -294,6 +650,56 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_does_not_leak_out")
     CHECK_EQ("nil", toString(requireTypeAtPosition({8, 29})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_does_not_leak_out_breaking")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}})
+            for _, record in x do
+                if typeof(record.value) == "string" then
+                    break
+                else
+                    type Foo = number
+                end
+
+                local foo: Foo = record.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_ERROR_COUNT(1, result);
+
+    CHECK_EQ("Unknown type 'Foo'", toString(result.errors[0]));
+
+    CHECK_EQ("nil", toString(requireTypeAtPosition({9, 43})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "type_alias_does_not_leak_out_continuing")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}})
+            for _, record in x do
+                if typeof(record.value) == "string" then
+                    continue
+                else
+                    type Foo = number
+                end
+
+                local foo: Foo = record.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_ERROR_COUNT(1, result);
+
+    CHECK_EQ("Unknown type 'Foo'", toString(result.errors[0]));
+
+    CHECK_EQ("nil", toString(requireTypeAtPosition({9, 43})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "prototyping_and_visiting_alias_has_the_same_scope")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};
@@ -320,6 +726,56 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "prototyping_and_visiting_alias_has_the_same_
     CHECK_EQ("nil", toString(requireTypeAtPosition({8, 29})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "prototyping_and_visiting_alias_has_the_same_scope_breaking")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}})
+            for _, record in x do
+                type Foo = number
+
+                if typeof(record.value) == "string" then
+                    break
+                end
+
+                local foo: Foo = record.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_ERROR_COUNT(1, result);
+
+    CHECK_EQ("Type 'nil' could not be converted into 'number'", toString(result.errors[0]));
+
+    CHECK_EQ("nil", toString(requireTypeAtPosition({9, 43})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "prototyping_and_visiting_alias_has_the_same_scope_continuing")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        local function f(x: {{value: string?}})
+            for _, record in x do
+                type Foo = number
+
+                if typeof(record.value) == "string" then
+                    continue
+                end
+
+                local foo: Foo = record.value
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_ERROR_COUNT(1, result);
+
+    CHECK_EQ("Type 'nil' could not be converted into 'number'", toString(result.errors[0]));
+
+    CHECK_EQ("nil", toString(requireTypeAtPosition({9, 43})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "tagged_unions")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};
@@ -355,6 +811,72 @@ TEST_CASE_FIXTURE(BuiltinsFixture, "tagged_unions")
     CHECK_EQ("Err<E>", toString(requireTypeAtPosition({16, 19})));
 }
 
+TEST_CASE_FIXTURE(BuiltinsFixture, "tagged_unions_breaking")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        type Ok<T> = { tag: "ok", value: T }
+        type Err<E> = { tag: "err", error: E }
+        type Result<T, E> = Ok<T> | Err<E>
+
+        local function process<T, E>(results: {Result<T, E>})
+            for _, result in results do
+                if result.tag == "ok" then
+                    local tag = result.tag
+                    local val = result.value
+
+                    break
+                end
+
+                local tag = result.tag
+                local err = result.error
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+
+    CHECK_EQ("\"ok\"", toString(requireTypeAtPosition({8, 39})));
+    CHECK_EQ("T", toString(requireTypeAtPosition({9, 39})));
+
+    CHECK_EQ("\"err\"", toString(requireTypeAtPosition({14, 35})));
+    CHECK_EQ("E", toString(requireTypeAtPosition({15, 35})));
+}
+
+TEST_CASE_FIXTURE(BuiltinsFixture, "tagged_unions_continuing")
+{
+    ScopedFastFlag sff{"LuauLoopControlFlowAnalysis", true};
+
+    CheckResult result = check(R"(
+        type Ok<T> = { tag: "ok", value: T }
+        type Err<E> = { tag: "err", error: E }
+        type Result<T, E> = Ok<T> | Err<E>
+
+        local function process<T, E>(results: {Result<T, E>})
+            for _, result in results do
+                if result.tag == "ok" then
+                    local tag = result.tag
+                    local val = result.value
+
+                    continue
+                end
+
+                local tag = result.tag
+                local err = result.error
+            end
+        end
+    )");
+
+    LUAU_REQUIRE_NO_ERRORS(result);
+
+    CHECK_EQ("\"ok\"", toString(requireTypeAtPosition({8, 39})));
+    CHECK_EQ("T", toString(requireTypeAtPosition({9, 39})));
+
+    CHECK_EQ("\"err\"", toString(requireTypeAtPosition({14, 35})));
+    CHECK_EQ("E", toString(requireTypeAtPosition({15, 35})));
+}
+
 TEST_CASE_FIXTURE(BuiltinsFixture, "do_assert_x")
 {
     ScopedFastFlag sff{"LuauTinyControlFlowAnalysis", true};