From 19105d2c90d71e260cd661236f9c7130af89dcf0 Mon Sep 17 00:00:00 2001
From: Michael Hatherly <michaelhatherly@gmail.com>
Date: Wed, 9 Sep 2015 15:08:51 +0200
Subject: [PATCH] Improve invalid doc expression error message.

Display the unexpanded form of the expression instead of its expansion.
---
 base/docs/Docs.jl | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/base/docs/Docs.jl b/base/docs/Docs.jl
index e5d74059d14f6..5df6a695e7c0d 100644
--- a/base/docs/Docs.jl
+++ b/base/docs/Docs.jl
@@ -521,6 +521,12 @@ __doc__!(meta, def) = false
 fexpr(ex) = isexpr(ex, :function, :stagedfunction, :(=)) && isexpr(ex.args[1], :call)
 
 function docm(meta, def, define = true)
+
+    err = (
+        "invalid doc expression:", def, isexpr(def, :macrocall) ?
+        "'$(def.args[1])' is not documentable. See 'help?> Docs.@__doc__' for details." : ""
+    )
+
     def′ = unblock(def)
 
     isexpr(def′, :quote) && isexpr(def′.args[1], :macrocall) &&
@@ -545,7 +551,7 @@ function docm(meta, def, define = true)
     isvar(def′)                ? objdoc(meta, def′) :
     isexpr(def′, :tuple)       ? multidoc(meta, def′.args) :
     __doc__!(meta, def′)       ? esc(def′) :
-    isa(def′, Expr)            ? error("invalid doc expression $def′") :
+    isa(def′, Expr)            ? error(strip(join(err, "\n\n"))) :
     objdoc(meta, def′)
 end