Stop useless suggestion of unsafeAddr (#10598)

Fixes #10594

compiler/semexprs.nim

@@ -15,7 +15,7 @@ const
   errXExpectsTypeOrValue = "'$1' expects a type or value"
   errVarForOutParamNeededX = "for a 'var' type a variable needs to be passed; but '$1' is immutable"
   errXStackEscape = "address of '$1' may not escape its stack frame"
-  errExprHasNoAddress = "expression has no address; maybe use 'unsafeAddr'"
+  errExprHasNoAddress = "expression has no address"
   errCannotInterpretNodeX = "cannot evaluate '$1'"
   errNamedExprExpected = "named expression expected"
   errNamedExprNotAllowed = "named expression not allowed here"

compiler/semmagic.nim

@@ -16,7 +16,12 @@ proc semAddr(c: PContext; n: PNode; isUnsafeAddr=false): PNode =
   if x.kind == nkSym:
     x.sym.flags.incl(sfAddrTaken)
   if isAssignable(c, x, isUnsafeAddr) notin {arLValue, arLocalLValue}:
-    localError(c.config, n.info, errExprHasNoAddress)
+    # Do not suggest the use of unsafeAddr if this expression already is a
+    # unsafeAddr
+    if isUnsafeAddr:
+      localError(c.config, n.info, errExprHasNoAddress)
+    else:
+      localError(c.config, n.info, errExprHasNoAddress & "; maybe use 'unsafeAddr'")
   result.add x
   result.typ = makePtrType(c, x.typ)
 

tests/errmsgs/t10594.nim

@@ -0,0 +1,7 @@
+discard """
+  errormsg: "expression has no address"
+  line: 7
+"""
+
+template foo(v: varargs[int]) = unsafeAddr v 
+foo(1, 2)