From 7ebb2baa6c0d3e0717bb79f746cf36a6095d31d7 Mon Sep 17 00:00:00 2001
From: Neelesh Chandola <neelesh.chandola@outlook.com>
Date: Mon, 9 Dec 2019 13:49:40 +0530
Subject: [PATCH] Assigning template to var/let/const gives a proper error
 (#12851)

* Assigning template to var/let/const gives a proper error

* Fix style
---
 compiler/semstmts.nim      | 14 +++++++++-----
 tests/errmsgs/t10489_a.nim |  2 +-
 tests/errmsgs/t10489_b.nim |  2 +-
 tests/errmsgs/t12844.nim   | 13 +++++++++++++
 4 files changed, 24 insertions(+), 7 deletions(-)
 create mode 100644 tests/errmsgs/t12844.nim

diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index 3abee2faf7..e8a5ae0387 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -36,7 +36,7 @@ const
   errRecursiveDependencyX = "recursive dependency: '$1'"
   errRecursiveDependencyIteratorX = "recursion is not supported in iterators: '$1'"
   errPragmaOnlyInHeaderOfProcX = "pragmas are only allowed in the header of a proc; redefinition of $1"
-  errCannotAssignMacroSymbol = "cannot assign macro symbol to $1 here. Forgot to invoke the macro with '()'?"
+  errCannotAssignMacroSymbol = "cannot assign $1 '$2' to '$3'. Did you mean to call the $1 with '()'?"
   errInvalidTypeDescAssign = "'typedesc' metatype is not valid here; typed '=' instead of ':'?"
 
 proc semDiscard(c: PContext, n: PNode): PNode =
@@ -449,8 +449,10 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
     if a[^1].kind != nkEmpty:
       def = semExprWithType(c, a[^1], {efAllowDestructor})
       if def.typ.kind == tyProc and def.kind == nkSym:
-        if def.sym.kind == skMacro:
-          localError(c.config, def.info, errCannotAssignMacroSymbol % "variable")
+        if def.sym.kind in {skMacro, skTemplate}:
+          localError(c.config, def.info, errCannotAssignMacroSymbol % [
+                          if def.sym.kind == skMacro: "macro" else: "template",
+                          def.sym.name.s, a[0].ident.s])
           def.typ = errorType(c)
       elif def.typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
         # prevent the all too common 'var x = int' bug:
@@ -590,8 +592,10 @@ proc semConst(c: PContext, n: PNode): PNode =
     # don't evaluate here since the type compatibility check below may add a converter
     var def = semExprWithType(c, a[^1])
     if def.typ.kind == tyProc and def.kind == nkSym:
-      if def.sym.kind == skMacro:
-        localError(c.config, def.info, errCannotAssignMacroSymbol % "constant")
+      if def.sym.kind in {skMacro, skTemplate}:
+        localError(c.config, def.info, errCannotAssignMacroSymbol % [
+          if def.sym.kind == skMacro: "macro" else: "template",
+          def.sym.name.s, a[0].ident.s])
         def.typ = errorType(c)
     elif def.typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
       # prevent the all too common 'const x = int' bug:
diff --git a/tests/errmsgs/t10489_a.nim b/tests/errmsgs/t10489_a.nim
index 7cfe0176cf..86659f7acd 100644
--- a/tests/errmsgs/t10489_a.nim
+++ b/tests/errmsgs/t10489_a.nim
@@ -1,5 +1,5 @@
 discard """
-errormsg: "cannot assign macro symbol to variable here"
+errormsg: "cannot assign macro 'm' to 'x1'. Did you mean to call the macro with '()'?"
 line: 9
 """
 
diff --git a/tests/errmsgs/t10489_b.nim b/tests/errmsgs/t10489_b.nim
index e690f028a7..1182b45126 100644
--- a/tests/errmsgs/t10489_b.nim
+++ b/tests/errmsgs/t10489_b.nim
@@ -1,5 +1,5 @@
 discard """
-errormsg: "cannot assign macro symbol to constant here"
+errormsg: "cannot assign macro 'm' to 'x2'. Did you mean to call the macro with '()'?"
 line: 9
 """
 
diff --git a/tests/errmsgs/t12844.nim b/tests/errmsgs/t12844.nim
new file mode 100644
index 0000000000..999d26255f
--- /dev/null
+++ b/tests/errmsgs/t12844.nim
@@ -0,0 +1,13 @@
+discard """
+cmd: "nim check $file"
+errormsg: "cannot assign template 'z' to 'y'. Did you mean to call the template with '()'?"
+nimout: '''
+t12844.nim(11, 11) Error: cannot assign template 'z' to 'x'. Did you mean to call the template with '()'?
+t12844.nim(12, 9) Error: cannot assign template 'z' to 'y'. Did you mean to call the template with '()'?'''
+"""
+
+template z*(args: varargs[string, `$`]) =
+  discard
+const x = z
+var y = z
+