destruct: Removal of residual patterns (#1737)

fixes #1560 from xvw/1560-destruct-should-not-produce-remanent-cases
ocaml · Feb 26, 2024 · 3488e07 · 3488e07
2 parents 7017cc2 + af62e12
commit 3488e07
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diff --git a/CHANGES.md b/CHANGES.md
@@ -1,3 +1,9 @@
+merlin NEXT_VERSION
+==================
+
+  + merlin binary
+    - destruct: Removal of residual patterns (#1737, fixes #1560)
+
 merlin 4.14
 ===========
 Thu Feb 22 14:00:42 CET 2024

diff --git a/src/analysis/destruct.ml b/src/analysis/destruct.ml
@@ -584,10 +584,7 @@ let rec node config source selected_node parents =
                   subst_patt patt ~by top_patt
                 )
               in
-              let patterns =
-                List.rev_append rev_before
-                  (List.append new_branches after)
-              in
+              let patterns = after @ rev_before @ new_branches in
               let unused = Parmatch.return_unused patterns in
               let new_branches =
                 List.fold_left unused ~init:new_branches ~f:(fun branches u ->

diff --git a/tests/test-dirs/destruct/issue1560.t b/tests/test-dirs/destruct/issue1560.t
@@ -0,0 +1,162 @@
+  $ $MERLIN single case-analysis -start 2:29 -end 2:29 \
+  > -filename main.ml <<EOF
+  > type t = A of int | B | C
+  > let f = function A x -> x | _ -> 1
+  > EOF
+  {
+    "class": "return",
+    "value": [
+      {
+        "start": {
+          "line": 2,
+          "col": 28
+        },
+        "end": {
+          "line": 2,
+          "col": 29
+        }
+      },
+      "B | C"
+    ],
+    "notifications": []
+  }
+
+  $ $MERLIN single case-analysis -start 2:18 -end 2:18 \
+  > -filename main.ml <<EOF
+  > type t = A of int | B | C
+  > let f = function A x -> x
+  > EOF
+  {
+    "class": "return",
+    "value": [
+      {
+        "start": {
+          "line": 2,
+          "col": 25
+        },
+        "end": {
+          "line": 2,
+          "col": 25
+        }
+      },
+      "
+  | B | C -> _"
+    ],
+    "notifications": []
+  }
+
+
+  $ $MERLIN single case-analysis -start 2:29 -end 2:29 \
+  > -filename main.ml <<EOF
+  > type t = A of int | B | C
+  > let f = function A 0 -> 0 | _ -> 1
+  > EOF
+  {
+    "class": "return",
+    "value": [
+      {
+        "start": {
+          "line": 2,
+          "col": 28
+        },
+        "end": {
+          "line": 2,
+          "col": 29
+        }
+      },
+      "A _ | B | C"
+    ],
+    "notifications": []
+  }
+
+  $ $MERLIN single case-analysis -start 2:29 -end 2:29 \
+  > -filename main.ml <<EOF
+  > type t = A of int | B | C
+  > let f = function A x -> x | _ -> 1 | C -> 2
+  > EOF
+  {
+    "class": "return",
+    "value": [
+      {
+        "start": {
+          "line": 2,
+          "col": 28
+        },
+        "end": {
+          "line": 2,
+          "col": 29
+        }
+      },
+      "B"
+    ],
+    "notifications": []
+  }
+
+  $ $MERLIN single case-analysis -start 2:38 -end 2:38 \
+  > -filename main.ml <<EOF
+  > type t = A of int | B | C
+  > let f = function A x -> x | C -> 2 | _ -> 1
+  > EOF
+  {
+    "class": "return",
+    "value": [
+      {
+        "start": {
+          "line": 2,
+          "col": 37
+        },
+        "end": {
+          "line": 2,
+          "col": 38
+        }
+      },
+      "B"
+    ],
+    "notifications": []
+  }
+
+  $ $MERLIN single case-analysis -start 2:47 -end 2:47 \
+  > -filename main.ml <<EOF
+  > type t = A of int | B | C | D
+  > let f = function A x -> x | B -> 2 | D -> 1 | _ -> 3
+  > EOF
+  {
+    "class": "return",
+    "value": [
+      {
+        "start": {
+          "line": 2,
+          "col": 46
+        },
+        "end": {
+          "line": 2,
+          "col": 47
+        }
+      },
+      "C"
+    ],
+    "notifications": []
+  }
+
+  $ $MERLIN single case-analysis -start 2:47 -end 2:47 \
+  > -filename main.ml <<EOF
+  > type t = A of int | B | C | D
+  > let f = function A 2 -> 2 | B -> 2 | D -> 1 | _ -> 3
+  > EOF
+  {
+    "class": "return",
+    "value": [
+      {
+        "start": {
+          "line": 2,
+          "col": 46
+        },
+        "end": {
+          "line": 2,
+          "col": 47
+        }
+      },
+      "A _ | C"
+    ],
+    "notifications": []
+  }