From 6b9a139f7f27422bc2d7dc3fad20d589518a93b5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Arne=20D=C3=B6ring?= <arne.doering@gmx.net>
Date: Tue, 19 Feb 2019 12:21:42 +0100
Subject: [PATCH] error message for accidental use of macro (#10490)

* error message for accidental use of macro
---
 compiler/semstmts.nim      | 11 +++++++++--
 tests/errmsgs/t10489_a.nim |  9 +++++++++
 tests/errmsgs/t10489_b.nim |  9 +++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)
 create mode 100644 tests/errmsgs/t10489_a.nim
 create mode 100644 tests/errmsgs/t10489_b.nim

diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index cd570caad..3827da220 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -448,10 +448,14 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
     var def: PNode = c.graph.emptyNode
     if a.sons[length-1].kind != nkEmpty:
       def = semExprWithType(c, a.sons[length-1], {efAllowDestructor})
-      if def.typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
+      if def.typ.kind == tyProc and def.kind == nkSym and def.sym.kind == skMacro:
+        localError(c.config, def.info, "cannot assign macro symbol to variable here. Forgot to invoke the macro with '()'?")
+        def.typ = errorType(c)
+      elif def.typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
         # prevent the all too common 'var x = int' bug:
         localError(c.config, def.info, "'typedesc' metatype is not valid here; typed '=' instead of ':'?")
         def.typ = errorType(c)
+
       if typ != nil:
         if typ.isMetaType:
           def = inferWithMetatype(c, typ, def)
@@ -583,7 +587,10 @@ proc semConst(c: PContext, n: PNode): PNode =
       localError(c.config, a.sons[length-1].info, errConstExprExpected)
       continue
 
-    if def.typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
+    if def.typ.kind == tyProc and def.kind == nkSym and def.sym.kind == skMacro:
+        localError(c.config, def.info, "cannot assign macro symbol to constant here. Forgot to invoke the macro with '()'?")
+        def.typ = errorType(c)
+    elif def.typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
       # prevent the all too common 'const x = int' bug:
       localError(c.config, def.info, "'typedesc' metatype is not valid here; typed '=' instead of ':'?")
       def.typ = errorType(c)
diff --git a/tests/errmsgs/t10489_a.nim b/tests/errmsgs/t10489_a.nim
new file mode 100644
index 000000000..7cfe0176c
--- /dev/null
+++ b/tests/errmsgs/t10489_a.nim
@@ -0,0 +1,9 @@
+discard """
+errormsg: "cannot assign macro symbol to variable here"
+line: 9
+"""
+
+macro m(body: untyped): untyped =
+  body
+
+let x1 = m
diff --git a/tests/errmsgs/t10489_b.nim b/tests/errmsgs/t10489_b.nim
new file mode 100644
index 000000000..e690f028a
--- /dev/null
+++ b/tests/errmsgs/t10489_b.nim
@@ -0,0 +1,9 @@
+discard """
+errormsg: "cannot assign macro symbol to constant here"
+line: 9
+"""
+
+macro m(body: untyped): untyped =
+  body
+
+const x2 = m