From 3237e0c780ee3d064f12d5e26f70434f847c37c5 Mon Sep 17 00:00:00 2001
From: hlaaftana <atadorukaydin@gmail.com>
Date: Thu, 16 Aug 2018 20:22:48 +0300
Subject: [PATCH 1/2] Fix #8610 and #8654

---
 compiler/semstmts.nim     | 3 +++
 compiler/types.nim        | 4 ++--
 tests/errmsgs/t8610.nim   | 8 ++++++++
 tests/errmsgs/t8654_1.nim | 8 ++++++++
 tests/errmsgs/t8654_2.nim | 7 +++++++
 5 files changed, 28 insertions(+), 2 deletions(-)
 create mode 100644 tests/errmsgs/t8610.nim
 create mode 100644 tests/errmsgs/t8654_1.nim
 create mode 100644 tests/errmsgs/t8654_2.nim

diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index 170ac799ef16..dfc68337253f 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -409,6 +409,9 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
     var typ: PType
     if a.sons[length-2].kind != nkEmpty:
       typ = semTypeNode(c, a.sons[length-2], nil)
+      if typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
+        localError(c.config, a.sons[length-2].info, "'typedesc' metatype is not valid here")
+        continue
     else:
       typ = nil
     var def: PNode = c.graph.emptyNode
diff --git a/compiler/types.nim b/compiler/types.nim
index 80624502c5a4..c4631c6b67f3 100644
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -1183,8 +1183,8 @@ proc typeAllowedAux(marker: var IntSet, typ: PType, kind: TSymKind,
     if result.isNil and t.sons[0] != nil:
       result = typeAllowedAux(marker, t.sons[0], skResult, flags)
   of tyTypeDesc:
-    # XXX: This is still a horrible idea...
-    result = nil
+    # Could be inside a macro, so var and let are allowed here and checked later
+    if kind notin {skParam, skResult, skVar, skLet}: result = t
   of tyExpr, tyStmt, tyStatic:
     if kind notin {skParam, skResult}: result = t
   of tyVoid:
diff --git a/tests/errmsgs/t8610.nim b/tests/errmsgs/t8610.nim
new file mode 100644
index 000000000000..1200e59a6427
--- /dev/null
+++ b/tests/errmsgs/t8610.nim
@@ -0,0 +1,8 @@
+discard """
+  errormsg: "invalid type for const: type int"
+  line: 6
+"""
+
+const Foo=int
+echo Foo is int # true
+echo int is Foo # Error: type expected
diff --git a/tests/errmsgs/t8654_1.nim b/tests/errmsgs/t8654_1.nim
new file mode 100644
index 000000000000..ed7d7b21fdeb
--- /dev/null
+++ b/tests/errmsgs/t8654_1.nim
@@ -0,0 +1,8 @@
+discard """
+  errormsg: "'typedesc' metatype is not valid here"
+  line: 6
+"""
+
+var a: typedesc
+a = typedesc[int]
+echo a is typedesc[int]
diff --git a/tests/errmsgs/t8654_2.nim b/tests/errmsgs/t8654_2.nim
new file mode 100644
index 000000000000..82642e95b931
--- /dev/null
+++ b/tests/errmsgs/t8654_2.nim
@@ -0,0 +1,7 @@
+discard """
+  errormsg: "invalid type for const: typedesc"
+  line: 6
+"""
+
+const a: typedesc = typedesc[int]
+echo a is typedesc[int]

From d97905fdfe2e57d2ee7d7554088548ab903b7a69 Mon Sep 17 00:00:00 2001
From: hlaaftana <atadorukaydin@gmail.com>
Date: Thu, 16 Aug 2018 22:13:10 +0300
Subject: [PATCH 2/2] Improved const typedesc error message

---
 compiler/semstmts.nim     | 3 +++
 tests/errmsgs/t8610.nim   | 2 +-
 tests/errmsgs/t8654_2.nim | 2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index dfc68337253f..895a151b31c4 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -542,6 +542,9 @@ proc semConst(c: PContext, n: PNode): PNode =
     if typ == nil:
       localError(c.config, a.sons[2].info, errConstExprExpected)
       continue
+    if typ.kind == tyTypeDesc:
+      localError(c.config, a.info, "cannot have typedesc as const value, " &
+        "use 'type $1 = $2' instead", [$a.sons[0], typeToString(def.typ.skipTypes({tyTypeDesc}))])
     if typeAllowed(typ, skConst) != nil and def.kind != nkNilLit:
       localError(c.config, a.info, "invalid type for const: " & typeToString(typ))
       continue
diff --git a/tests/errmsgs/t8610.nim b/tests/errmsgs/t8610.nim
index 1200e59a6427..b6ed1637d176 100644
--- a/tests/errmsgs/t8610.nim
+++ b/tests/errmsgs/t8610.nim
@@ -1,5 +1,5 @@
 discard """
-  errormsg: "invalid type for const: type int"
+  errormsg: "cannot have typedesc as const value, use 'type Foo = int' instead"
   line: 6
 """
 
diff --git a/tests/errmsgs/t8654_2.nim b/tests/errmsgs/t8654_2.nim
index 82642e95b931..7f80d96afc9e 100644
--- a/tests/errmsgs/t8654_2.nim
+++ b/tests/errmsgs/t8654_2.nim
@@ -1,5 +1,5 @@
 discard """
-  errormsg: "invalid type for const: typedesc"
+  errormsg: "cannot have typedesc as const value, use 'type a = int' instead"
   line: 6
 """