Showcase stack overflow bug with polyvariants (#851)

* showcase stack overflow bug with polyvariants

* Mark where the stack overflow happens.

* try something

* changelog

* remove debug

---------

Co-authored-by: Cristiano Calcagno <cristianoc@users.noreply.github.com>

Author: zth

CHANGELOG.md

@@ -21,6 +21,7 @@
 - Proper default for `"uncurried"` in V11 projects. https://github.com/rescript-lang/rescript-vscode/pull/867
 - Treat `result` type as a proper built in type. https://github.com/rescript-lang/rescript-vscode/pull/860
 - Fix infinite loop when resolving inferred completions when several values in scope has the same name. https://github.com/rescript-lang/rescript-vscode/pull/869
+- Fix crash when trying to print recursive polymorphic variants without a concrete definition. https://github.com/rescript-lang/rescript-vscode/pull/851
 
 #### :nail_care: Polish
 

analysis/src/PrintType.ml

@@ -1,5 +1,6 @@
 let printExpr ?(lineWidth = 60) typ =
   Printtyp.reset_names ();
+  Printtyp.reset_and_mark_loops typ;
   Res_doc.toString ~width:lineWidth
     (Res_outcome_printer.printOutTypeDoc (Printtyp.tree_of_typexp false typ))
 

analysis/tests/src/PolyRec.res

@@ -0,0 +1,14 @@
+let rec sum = x =>
+  switch x {
+  | #Leaf => 0
+  | #Node(value, left, right) => value + left->sum + right->sum
+  }
+
+let myTree = #Node(
+  1,
+  #Node(2, #Node(4, #Leaf, #Leaf), #Node(6, #Leaf, #Leaf)),
+  #Node(3, #Node(5, #Leaf, #Leaf), #Node(7, #Leaf, #Leaf)),
+)
+
+let () = myTree->sum->Js.log
+//        ^hov

analysis/tests/src/expected/CompletionPattern.res.txt

@@ -129,7 +129,7 @@ Path f
     "label": "optThird",
     "kind": 5,
     "tags": [],
-    "detail": "optThird: option<[#second(someRecord) | #first]>\n\nsomeRecord",
+    "detail": "optThird: option<[#first | #second(someRecord)]>\n\nsomeRecord",
     "documentation": null
   }, {
     "label": "nest",
@@ -150,7 +150,7 @@ Path f
     "label": "optThird",
     "kind": 5,
     "tags": [],
-    "detail": "optThird: option<[#second(someRecord) | #first]>\n\nsomeRecord",
+    "detail": "optThird: option<[#first | #second(someRecord)]>\n\nsomeRecord",
     "documentation": null
   }, {
     "label": "nest",
@@ -189,7 +189,7 @@ Path z
     "label": "optThird",
     "kind": 5,
     "tags": [],
-    "detail": "optThird: option<[#second(someRecord) | #first]>\n\nsomeRecord",
+    "detail": "optThird: option<[#first | #second(someRecord)]>\n\nsomeRecord",
     "documentation": null
   }]
 
@@ -267,7 +267,7 @@ Path f
     "label": "optThird",
     "kind": 5,
     "tags": [],
-    "detail": "optThird: option<[#second(someRecord) | #first]>\n\nsomeRecord",
+    "detail": "optThird: option<[#first | #second(someRecord)]>\n\nsomeRecord",
     "documentation": null
   }, {
     "label": "nest",
@@ -360,7 +360,7 @@ Path z
     "label": "optThird",
     "kind": 5,
     "tags": [],
-    "detail": "optThird: option<[#second(someRecord) | #first]>\n\nsomeRecord",
+    "detail": "optThird: option<[#first | #second(someRecord)]>\n\nsomeRecord",
     "documentation": null
   }, {
     "label": "nest",
@@ -451,7 +451,7 @@ Path b
     "label": "optThird",
     "kind": 5,
     "tags": [],
-    "detail": "optThird: option<[#second(someRecord) | #first]>\n\nsomeRecord",
+    "detail": "optThird: option<[#first | #second(someRecord)]>\n\nsomeRecord",
     "documentation": null
   }, {
     "label": "nest",

analysis/tests/src/expected/Hover.res.txt

@@ -77,10 +77,10 @@ Hover src/Hover.res 106:21
 {"contents": {"kind": "markdown", "value": "```rescript\nint\n```"}}
 
 Hover src/Hover.res 116:16
-{"contents": {"kind": "markdown", "value": "```rescript\nAA.cond<[< #str(string)]> => AA.cond<[< #str(string)]>\n```\n\n---\n\n```\n \n```\n```rescript\ntype AA.cond<'a> = 'a\n  constraint 'a = [< #str(string)]\n```\nGo to: [Type definition](command:rescript-vscode.go_to_location?%5B%22Hover.res%22%2C110%2C2%5D)\n"}}
+{"contents": {"kind": "markdown", "value": "```rescript\nAA.cond<([< #str(string)] as 'a)> => AA.cond<'a>\n```\n\n---\n\n```\n \n```\n```rescript\ntype AA.cond<'a> = 'a\n  constraint 'a = [< #str(string)]\n```\nGo to: [Type definition](command:rescript-vscode.go_to_location?%5B%22Hover.res%22%2C110%2C2%5D)\n"}}
 
 Hover src/Hover.res 119:25
-{"contents": {"kind": "markdown", "value": "```rescript\nAA.cond<[< #str(string)]> => AA.cond<[< #str(string)]>\n```\n\n---\n\n```\n \n```\n```rescript\ntype AA.cond<'a> = 'a\n  constraint 'a = [< #str(string)]\n```\nGo to: [Type definition](command:rescript-vscode.go_to_location?%5B%22Hover.res%22%2C110%2C2%5D)\n"}}
+{"contents": {"kind": "markdown", "value": "```rescript\nAA.cond<([< #str(string)] as 'a)> => AA.cond<'a>\n```\n\n---\n\n```\n \n```\n```rescript\ntype AA.cond<'a> = 'a\n  constraint 'a = [< #str(string)]\n```\nGo to: [Type definition](command:rescript-vscode.go_to_location?%5B%22Hover.res%22%2C110%2C2%5D)\n"}}
 
 Hover src/Hover.res 122:3
 Nothing at that position. Now trying to use completion.

analysis/tests/src/expected/PolyRec.res.txt

@@ -0,0 +1,3 @@
+Hover src/PolyRec.res 12:10
+{"contents": {"kind": "markdown", "value": "```rescript\n([#Leaf | #Node(int, 'a, 'a)] as 'a)\n```"}}
+