[flow][tests] Do not aggressively invalidate refinements in loops for…

… const-like variables

Summary:
This diff fixed the issue shown in the previous diff. The problem is that we see the Val has changed, because inside the loop we have a latent refinement (from `if (f(v)`) being applied to it.

While in general it seems to hard to avoid these bad interactions, I think we can at least avoid it for const-like variables. For const-like variables, we should be able to always keep the outer refinements.

Changelog: [fix] Flow will no longer invalidate refinements made before the loop for const-like variables within a loop ([example](https://flow.org/try/#1N4Igxg9gdgZglgcxALlAIwIZoKYBsD6uEEAztvhgE6UYCe+JADpdhgCYowa5kA0I2KAFcAtiRQAXSkOz9sADwxgJ+NPTbYuQ3BMnTZA+Y2yU4IwRO4A6SFBIrGVDGM7c+h46fNRLuKxJIGWh8MeT0ZfhYlCStpHzNsFBAMIQkIEQwJODAQfiEyfBE4eWw2fDgofDBMsAALfAA3KjgsXGxxZC4eAw0G-GhcWn9aY3wWZldu-g1mbGqJUoBaCRHEzrcDEgBrbAk62kXhXFxJ923d-cPRHEpTgyEoMDaqZdW7vKgoOfaSKgOKpqmDA+d4gB5fMA-P6LCCMLLQbiLOoYCqgh6-GDYRYIXYLSgkRZkCR4jpddwPfJLZjpOBkO4AX34kA0SQ0Tyo2AABDAHso4NBuQAKBrITn2UxQBAASlFaGIzygAG4ADpQVU8x7wqCchb2YWi8UVBCcgA+nKOuClnOAqs5nLgME5ws5AF4XebtJbrba7ZyWBIhJQlT76T6AO61OBtJ1SGRWm3a30Op0wYVS+OcgD0mc5swa-Pyg05JkoEEovHNEDDnIgW1FUGgV2Ofs0FWw3gk9pInJ2cJ9vpbAaDKsTdtDifH49yIAaJhI-KgSQy9hMIHpQA))

Reviewed By: jbrown215

Differential Revision: D68224844

fbshipit-source-id: 27db5bc4555ab4ce1d120997e8764f5d53b04a78

src/analysis/env_builder/name_resolver.ml

@@ -3382,7 +3382,7 @@ module Make (Context : C) (FlowAPIUtils : F with type cx = Context.t) :
                 let {
                   PartialEnvSnapshot.env_val = post_env_val;
                   heap_refinements = post_env_heap_refinements;
-                  def_loc = _;
+                  def_loc;
                 } =
                   match post_env_v with
                   | Some v -> v
@@ -3418,7 +3418,22 @@ module Make (Context : C) (FlowAPIUtils : F with type cx = Context.t) :
                     post_env_heap_refinements
                     acc
                 in
-                if Val.id_of_val pre_env_val = Val.id_of_val post_env_val then
+                let is_definitely_const_like =
+                  match def_loc with
+                  | None -> false
+                  | Some loc ->
+                    not
+                      (Invalidation_api.should_invalidate
+                         ~all:true
+                         invalidation_caches
+                         prepass_info
+                         prepass_values
+                         loc
+                      )
+                in
+                if
+                  is_definitely_const_like || Val.id_of_val pre_env_val = Val.id_of_val post_env_val
+                then
                   (acc, None)
                 else
                   (RefinementKey.lookup_of_name name :: acc, None)

tests/refinements/loop_incorrect_invalidation_regression_test.js

@@ -6,7 +6,7 @@
       return;
     }
     while (true) {
-      if (f(v)) { // spurious error
+      if (f(v)) { // ok: non-null refinement is kept
         return;
       }
     }

tests/refinements/refinements.exp

@@ -7701,19 +7701,16 @@ References:
 
 Error -------------------------------------------------------------- loop_incorrect_invalidation_regression_test.js:9:13
 
-Cannot call `f` with `v` bound to `v` because null [1] is incompatible with string [2]. [incompatible-call]
+Refined at [1]
 
    loop_incorrect_invalidation_regression_test.js:9:13
-   9|       if (f(v)) { // spurious error
+   9|       if (f(v)) { // ok: non-null refinement is kept
                   ^
 
 References:
-   loop_incorrect_invalidation_regression_test.js:4:29
-   4|   function test(v: string | null) {
-                                  ^^^^ [1]
-   loop_incorrect_invalidation_regression_test.js:2:25
-   2|   declare function f(v: string): boolean;
-                              ^^^^^^ [2]
+   loop_incorrect_invalidation_regression_test.js:5:9
+   5|     if (v == null) {
+              ^^^^^^^^^ [1]
 
 
 Error --------------------------------------------------------------------------------------------- maybe_react.js:18:19