fixes #15280 [backport:1.2] (#15281)

* fixes #15280 [backport:1.2]

* make tests green again

* adapt tests

(cherry picked from commit 3f00a738db)

compiler/sem.nim

@@ -183,7 +183,7 @@ proc endsInNoReturn(n: PNode): bool =
   var it = n
   while it.kind in {nkStmtList, nkStmtListExpr} and it.len > 0:
     it = it.lastSon
-  result = it.kind in nkLastBlockStmts or
+  result = it.kind in (nkLastBlockStmts-{nkReturnStmt}) or
     it.kind in nkCallKinds and it[0].kind == nkSym and sfNoReturn in it[0].sym.flags
 
 proc commonType*(x: PType, y: PNode): PType =

tests/casestmt/tcasestmt.nim

@@ -258,7 +258,7 @@ func foo(input: string): int =
   try:
     parseInt(input)
   except:
-    return
+    0
 
 func foo2(b, input: string): int =
   case b:

tests/semreject/tmixing_return_and_exprs.nim

@@ -0,0 +1,44 @@
+discard """
+  errormsg: "expression 'len(src) shl 1' is of type 'int' and has to be used (or discarded)"
+  line: 19
+"""
+
+# bug #15280
+
+type
+  HexFlags* {.pure.} = enum
+    LowerCase,  ## Produce lowercase hexadecimal characters
+    PadOdd,     ## Pads odd strings
+    SkipSpaces, ## Skips all the whitespace characters inside of string
+    SkipPrefix  ## Skips `0x` and `x` prefixes at the begining of string
+
+
+proc bytesToHex*(src: openarray[byte], dst: var openarray[char],
+                 flags: set[HexFlags]): int =
+  if len(dst) == 0:
+    (len(src) shl 1)
+  else:
+    var halflast = false
+    let dstlen = len(dst)
+    var srclen = len(src)
+
+    if dstlen < (srclen shl 1):
+      if (dstlen and 1) == 1:
+        srclen = (dstlen - 1) shr 1
+        halflast = true
+      else:
+        srclen = (dstlen shr 1)
+
+    let lowercase = (HexFlags.LowerCase in flags)
+
+    var k = 0
+    for i in 0 ..< srclen:
+      let x = int(src[i])
+      inc(k, 2)
+
+    if halflast:
+      let x = int(src[srclen])
+      inc(k)
+
+    return k
+