byLent now takes a var input

Author: timotheecour

lib/std/decls.nim

@@ -22,7 +22,7 @@ template byaddr*(lhs, typ, ex) =
     let tmp: ptr typ = addr(ex)
   template lhs: untyped = tmp[]
 
-proc byLent*[T](a: T): lent T {.inline.} =
+proc byLent*[T](a: var T): lent T {.inline.} =
   ## Transforms `a` into a let param without copying; this is useful for overload
   ## resolution
   runnableExamples:

tests/js/taddr.nim

@@ -78,29 +78,39 @@ doAssert(someGlobalPtr[] == 5)
 someGlobalPtr[] = 10
 doAssert(someGlobal == 10)
 
-from std/decls import byLent
-
 block:
   # issue #14576
   # lots of these used to give: Error: internal error: genAddr: 2
+  proc byLentAny[T](a: T): lent T = a
+  proc byLentVar[T](a: var T): lent T = a # see also decls.byLent
   proc byPtr[T](a: T): ptr T = a.unsafeAddr
 
   block:
     let a = (10,11)
-    let (x,y) = byLent(a)
+    let (x,y) = byLentAny(a)
+    doAssert (x,y) == a
+  block:
+    var a = (10,11)
+    let (x,y) = byLentAny(a)
     doAssert (x,y) == a
 
   block:
     let a = 10
-    doAssert byLent(a) == 10
-    let a2 = byLent(a)
+    doAssert byLentAny(a) == 10
+    let a2 = byLentAny(a)
     doAssert a2 == 10
 
   block:
     let a = [11,12]
-    doAssert byLent(a) == [11,12]
+    doAssert byLentAny(a) == [11,12]
     let a2 = (11,)
-    doAssert byLent(a2) == (11,)
+    doAssert byLentAny(a2) == (11,)
+
+  block:
+    var a = [11,12]
+    doAssert byLentVar(a) == [11,12]
+    var a2 = (11,)
+    doAssert byLentVar(a2) == (11,)
 
   block:
     when defined(c) and defined(release):
@@ -114,9 +124,9 @@ block:
       doAssert byPtr(a3)[] == 14
 
   block:
-    proc byLent2[T](a: seq[T]): lent T = a[1]
+    proc byLentElem[T](a: seq[T]): lent T = a[1]
     var a = @[20,21,22]
-    doAssert byLent2(a) == 21
+    doAssert byLentElem(a) == 21
 
   block: # sanity checks
     proc bar[T](a: var T): var T = a