1 files changed, 27 insertions, 5 deletions
diff --git a/compiler/semcall.nim b/compiler/semcall.nim
index 71a9197b7..61d6113dc 100644
--- a/compiler/semcall.nim
+++ b/compiler/semcall.nim
@@ -224,6 +224,7 @@ const
   errButExpected = "but expected one of: "
   errUndeclaredField = "undeclared field: '$1'"
   errUndeclaredRoutine = "attempting to call undeclared routine: '$1'"
+  errBadRoutine = "attempting to call routine: '$1'$2"
   errAmbiguousCallXYZ = "ambiguous call; both $1 and $2 match for: $3"
 
 proc notFoundError*(c: PContext, n: PNode, errors: CandidateErrors) =
@@ -262,6 +263,30 @@ proc bracketNotFoundError(c: PContext; n: PNode) =
   else:
     notFoundError(c, n, errors)
 
+proc getMsgDiagnostic(c: PContext, flags: TExprFlags, n, f: PNode): string =
+  if c.compilesContextId > 0:
+    # we avoid running more diagnostic when inside a `compiles(expr)`, to
+    # errors while running diagnostic (see test D20180828T234921), and
+    # also avoid slowdowns in evaluating `compiles(expr)`.
+    discard
+  else:
+    var o: TOverloadIter
+    var sym = initOverloadIter(o, c, f)
+    while sym != nil:
+      proc toHumanStr(kind: TSymKind): string =
+        result = $kind
+        assert result.startsWith "sk"
+        result = result[2..^1].toLowerAscii
+      result &= "\n  found '$1' of kind '$2'" % [getSymRepr(c.config, sym), sym.kind.toHumanStr]
+      sym = nextOverloadIter(o, c, n)
+
+  let ident = considerQuotedIdent(c, f, n).s
+  if nfDotField in n.flags and nfExplicitCall notin n.flags:
+    result = errUndeclaredField % ident & result
+  else:
+    if result.len == 0: result = errUndeclaredRoutine % ident
+    else: result = errBadRoutine % [ident, result]
+
 proc resolveOverloads(c: PContext, n, orig: PNode,
                       filter: TSymKinds, flags: TExprFlags,
                       errors: var CandidateErrors,
@@ -330,11 +355,8 @@ proc resolveOverloads(c: PContext, n, orig: PNode,
       pickBest(callOp)
 
     if overloadsState == csEmpty and result.state == csEmpty:
-      if efNoUndeclared notin flags:
-        if nfDotField in n.flags and nfExplicitCall notin n.flags:
-          localError(c.config, n.info, errUndeclaredField % considerQuotedIdent(c, f, n).s)
-        else:
-          localError(c.config, n.info, errUndeclaredRoutine % considerQuotedIdent(c, f, n).s)
+      if efNoUndeclared notin flags: # for tests/pragmas/tcustom_pragma.nim
+        localError(c.config, n.info, getMsgDiagnostic(c, flags, n, f))
       return
     elif result.state != csMatch:
       if nfExprCall in n.flags: