Exception analysis: report on toplevel bindings of the form let () = ... and let _ = ....

Author: cristianoc

Changes.md

@@ -1,6 +1,7 @@
 # master
 - Exception analysis: add support for inner modules.
 - Exception analysis: correctly hide location of caught exceptions when other instances of the same exception are reported.
+- Exception analysis: report on toplevel bindings of the form `let () = ...` and `let _ = ...`.
 
 # 2.9.0
 - Model `exit(...)` as raising a fictional exception called `exit`.

examples/deadcode/src/exception.txt

@@ -91,8 +91,20 @@
   File "./Exn.res", line 179, characters 4-23
   redundantAnnotation raises nothing and is annotated with redundant @raises Invalid_argument
 
+  Exception Analysis
+  File "./Exn.res", line 181, characters 4-6
+  _x might raise A (Exn.res:181:9) and is not annotated with @raises A
+
+  Exception Analysis
+  File "./Exn.res", line 183, characters 4-5
+  _ might raise A (Exn.res:183:8) and is not annotated with @raises A
+
+  Exception Analysis
+  File "./Exn.res", line 185, characters 4-6
+  () might raise A (Exn.res:185:9) and is not annotated with @raises A
+
   Exception Analysis
   File "./ExnA.res", line 1, characters 4-7
   bar might raise Not_found (ExnA.res:1:16) and is not annotated with @raises Not_found
 
-  Analysis reported 24 issues (Exception Analysis:24)
+  Analysis reported 27 issues (Exception Analysis:27)

examples/deadcode/src/exception/Exn.bs.js

@@ -173,7 +173,13 @@ let redundant4 = () => {
 }
 
 @raises(exit)
-let exits = () => exit(1);
+let exits = () => exit(1)
 
 @raises(Invalid_argument)
-let redundantAnnotation = () => ()
+let redundantAnnotation = () => ()
+
+let _x = raise(A)
+
+let _ = raise(A)
+
+let () = raise(A)

examples/deadcode/src/exception/Exn.res

@@ -586,6 +586,10 @@ let traverseAst = {
       res;
     };
     switch (vb.vb_pat.pat_desc) {
+    | Tpat_any when isToplevel && !vb.vb_loc.loc_ghost => processBinding("_")
+    | Tpat_construct({txt: Longident.Lident("()")}, _, _)
+        when isToplevel && !vb.vb_loc.loc_ghost =>
+      processBinding("()")
     | Tpat_var(id, {loc: {loc_ghost}})
         when (isFunction || isToplevel) && !loc_ghost && !vb.vb_loc.loc_ghost =>
       processBinding(id |> Ident.name)