rebase, add test for #15650, will try removing finishOperand after

compiler/semexprs.nim

@@ -141,9 +141,9 @@ proc resolveSymChoice(c: PContext, n: var PNode, flags: TExprFlags = {}, expecte
   if isSymChoice(n) and efAllowSymChoice notin flags:
     # some contexts might want sym choices preserved for later disambiguation
     # in general though they are ambiguous
-    let first = n[0].sym
+    let first = n[0]
     if nfPreferredSym in first.flags:
-      n = n[0]
+      n = first
 
 proc semSymChoice(c: PContext, n: PNode, flags: TExprFlags = {}, expectedType: PType = nil): PNode =
   result = n

tests/template/tbaddeprecated.nim

@@ -0,0 +1,13 @@
+# issue #15650
+
+{.warningAsError[Deprecated]: on.}
+
+proc bar() {.deprecated.} = discard
+
+template foo() =
+  when false:
+    bar()
+  else:
+    discard
+
+foo()