From 3e47725c08b42515d17d77b3a6c9cc3029e5681c Mon Sep 17 00:00:00 2001
From: metagn <metagngn@gmail.com>
Date: Sat, 9 Nov 2024 14:33:23 +0300
Subject: [PATCH] gensym anonymous proc symbols (#24422)

fixes #14067, fixes #15004, fixes #19019

Anonymous procs are [added to
scope](https://github.com/nim-lang/Nim/blob/8091d76306c23b866af00d384b9b6f929ef8ed23/compiler/semstmts.nim#L2466)
with the name `:anonymous`. This means that if they have the same
signature in a scope, they can consider each other as redefinitions. To
prevent this, mark their symbols as `sfGenSym` so they do not get added
to scope or cause any name conflicts. The commented out `and not isAnon`
check wouldn't work because `isAnon` would not be true if the proc is
being resemmed, in which case the name field in the proc AST would have
the symbol of the anonymous proc rather than being empty.

There is a separate problem of default values in generic/normal procs
not opening new scopes which is partially responsible for #19019.
---
 compiler/semstmts.nim         |  1 +
 tests/proc/tanonprocresem.nim | 41 +++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)
 create mode 100644 tests/proc/tanonprocresem.nim

diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index 60778d25d687..8061f316df04 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -2359,6 +2359,7 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
   of nkEmpty:
     s = newSym(kind, c.cache.idAnon, c.idgen, c.getCurrOwner, n.info)
     s.flags.incl sfUsed
+    s.flags.incl sfGenSym
     n[namePos] = newSymNode(s)
   of nkSym:
     s = n[namePos].sym
diff --git a/tests/proc/tanonprocresem.nim b/tests/proc/tanonprocresem.nim
new file mode 100644
index 000000000000..320d01a78291
--- /dev/null
+++ b/tests/proc/tanonprocresem.nim
@@ -0,0 +1,41 @@
+block: # issue #19019
+  proc start(draw:proc=(proc()=echo "default"), init:proc=(proc()=echo "default"), reshape:proc=(proc()=echo "default"))=discard
+  start()
+
+block: # issue #14067
+  type
+    Result[T, E] = object
+
+    DataProc = proc(val: openArray[byte])
+    GetProc = proc (onData: DataProc): Result[bool, cstring]
+
+  func get[T, E](self: Result[T, E]): T =
+    discard
+
+  template `[]`[T, E](self: Result[T, E]): T =
+    self.get()
+
+  proc testKVStore() =
+    var v: seq[byte]
+    var p: GetProc
+
+    discard p(proc(data: openArray[byte]) =
+        v = @data
+      )[]
+
+  if false: testKVStore()
+
+import std/macros
+
+block: # issue #15004
+  macro fn(fun:untyped):untyped =
+    newTree(nnkTupleConstr, newLit"first", fun)
+
+  macro fn(key:string, fun:untyped):untyped =
+    newTree(nnkTupleConstr, newLit"second", fun)
+
+  let c = fn(proc(count:int):string =
+    return "x = " & $count
+  )
+  doAssert c[0] == "first"
+  doAssert c[1](123) == "x = 123"