fixes #22389; fixes #19840; don't fold paths containing addr (#23807)

fixes #22389;
fixes #19840

(cherry picked from commit 5c5e7a9b6e)
(cherry picked from commit 00e39185f1d59597d17b69bbccf8879e3427f928)

compiler/semfold.nim

@@ -688,10 +688,7 @@ proc getConstExpr(m: PSym, n: PNode; idgen: IdGenerator; g: ModuleGraph): PNode
     except DivByZeroDefect:
       localError(g.config, n.info, "division by zero")
   of nkAddr:
-    var a = getConstExpr(m, n[0], idgen, g)
-    if a != nil:
-      result = n
-      n[0] = a
+    result = nil # don't fold paths containing nkAddr
   of nkBracket, nkCurly:
     result = copyNode(n)
     for son in n.items:

compiler/transf.nim

@@ -53,6 +53,7 @@ type
     isIntroducingNewLocalVars: bool  # true if we are in `introducingNewLocalVars` (don't transform yields)
     contSyms, breakSyms: seq[PSym]  # to transform 'continue' and 'break'
     deferDetected, tooEarly: bool
+    inAddr: bool
     graph: ModuleGraph
     idgen: IdGenerator
 
@@ -1038,7 +1039,10 @@ proc transform(c: PTransf, n: PNode): PNode =
   of nkHiddenAddr:
     result = transformAddrDeref(c, n, {nkHiddenDeref})
   of nkAddr:
+    let oldInAddr = c.inAddr
+    c.inAddr = true
     result = transformAddrDeref(c, n, {nkDerefExpr, nkHiddenDeref})
+    c.inAddr = oldInAddr
   of nkDerefExpr:
     result = transformAddrDeref(c, n, {nkAddr, nkHiddenAddr})
   of nkHiddenDeref:
@@ -1118,7 +1122,7 @@ proc transform(c: PTransf, n: PNode): PNode =
   let exprIsPointerCast = n.kind in {nkCast, nkConv, nkHiddenStdConv} and
                           n.typ != nil and
                           n.typ.kind == tyPointer
-  if not exprIsPointerCast:
+  if not exprIsPointerCast and not c.inAddr:
     var cnst = getConstExpr(c.module, result, c.idgen, c.graph)
     # we inline constants if they are not complex constants:
     if cnst != nil and not dontInlineConstant(n, cnst):

tests/vm/tconsttable.nim

@@ -17,3 +17,18 @@ x = "ah"
 echo foo[x]
 x = "possible."
 echo foo[x]
+
+block: # bug #19840
+  const testBytes = [byte 0xD8, 0x08, 0xDF, 0x45, 0x00, 0x3D, 0x00, 0x52, 0x00, 0x61]
+  var tempStr = "__________________"
+
+  tempStr.prepareMutation
+  copyMem(addr tempStr[0], addr testBytes[0], testBytes.len)
+
+block: # bug #22389
+  func foo(): ptr UncheckedArray[byte] =
+    const bar = [77.byte]
+    cast[ptr UncheckedArray[byte]](addr bar[0])
+
+  doAssert foo()[0] == 77
+