fixes #16069; [backport:1.2] [backport:1.4] (#16115)

* fixes #16069; refs https://github.com/nim-lang/RFCs/issues/257 [backport:1.2] [backport:1.4]

* make tests green again

compiler/ccgexprs.nim

@@ -881,6 +881,7 @@ proc genFieldCheck(p: BProc, e: PNode, obj: Rope, field: PSym) =
               [rdLoc(test), strLit, raiseInstr(p)])
 
 proc genCheckedRecordField(p: BProc, e: PNode, d: var TLoc) =
+  assert e[0].kind == nkDotExpr
   if optFieldCheck in p.options:
     var a: TLoc
     genRecordFieldAux(p, e[0], d, a)

compiler/semfold.nim

@@ -685,6 +685,7 @@ proc getConstExpr(m: PSym, n: PNode; idgen: IdGenerator; g: ModuleGraph): PNode
   of nkBracketExpr: result = foldArrayAccess(m, n, idgen, g)
   of nkDotExpr: result = foldFieldAccess(m, n, idgen, g)
   of nkCheckedFieldExpr:
+    assert n[0].kind == nkDotExpr
     result = foldFieldAccess(m, n[0], idgen, g)
   of nkStmtListExpr:
     var i = 0

compiler/transf.nim

@@ -1002,6 +1002,11 @@ proc transform(c: PTransf, n: PNode): PNode =
     return n
   of nkExceptBranch:
     result = transformExceptBranch(c, n)
+  of nkCheckedFieldExpr:
+    result = transformSons(c, n)
+    if result[0].kind != nkDotExpr:
+      # simplfied beyond a dot expression --> simplify further.
+      result = result[0]
   else:
     result = transformSons(c, n)
   when false:

compiler/trees.nim

@@ -211,6 +211,6 @@ proc stupidStmtListExpr*(n: PNode): bool =
 proc dontInlineConstant*(orig, cnst: PNode): bool {.inline.} =
   # symbols that expand to a complex constant (array, etc.) should not be
   # inlined, unless it's the empty array:
-  result = orig.kind == nkSym and
+  result = orig.kind != cnst.kind and
            cnst.kind in {nkCurly, nkPar, nkTupleConstr, nkBracket, nkObjConstr} and
            cnst.len > ord(cnst.kind == nkObjConstr)

tests/arc/topt_no_cursor.nim

@@ -46,7 +46,7 @@ var
   lvalue
   lnext
   _
-`=copy`(lresult, [123])
+lresult = @[123]
 _ = (
   let blitTmp = lresult
   blitTmp, ";")

tests/misc/taddr.nim

@@ -102,17 +102,6 @@ block:
     let a2 = (11,)
     doAssert byLent(a2) == (11,)
 
-  block:
-    when (defined(c) or defined(cpp)) and defined(release):
-      discard # probably not a bug since optimizer is free to pass by value, and `unsafeAddr` is used
-    else:
-      var a = @[12]
-      doAssert byPtr(a)[] == @[12]
-      let a2 = [13]
-      doAssert byPtr(a2)[] == [13]
-      let a3 = 14
-      doAssert byPtr(a3)[] == 14
-
   block:
     proc byLent2[T](a: seq[T]): lent T = a[1]
     var a = @[20,21,22]

tests/vm/tconstobj.nim

@@ -3,6 +3,7 @@ discard """
 (name: "hello")
 (-1, 0)
 (FirstName: "James", LastName: "Franco")
+[1, 2, 3]
 '''
 """
 
@@ -75,3 +76,20 @@ static: # issue #11861
 static: # issue #15662
   proc a(T: typedesc) = echo T.type
   a((int, int))
+
+# bug #16069
+type
+  E = enum
+    val1, val2
+  Obj = object
+    case k: E
+    of val1:
+      x: array[3, int]
+    of val2:
+      y: uint32
+
+const
+  foo = [1, 2, 3]
+  arr = Obj(k: val1, x: foo)
+
+echo arr.x