From d0b60f1fe3f82facec7f99f39b8bf188be3661a0 Mon Sep 17 00:00:00 2001
From: LemonBoy <LemonBoy@users.noreply.github.com>
Date: Sun, 8 Jul 2018 22:07:45 +0200
Subject: [PATCH] Generate dynlib strings as a single rope (#8247)

In order not to trip the optimization in genInfixCall we have to do so.
The same trick is also used in setExternName.

Fixes #8241
---
 compiler/cgen.nim   | 4 +++-
 tests/cpp/t8241.nim | 7 +++++++
 2 files changed, 10 insertions(+), 1 deletion(-)
 create mode 100644 tests/cpp/t8241.nim

diff --git a/compiler/cgen.nim b/compiler/cgen.nim
index a57192f9cd..32891c62ca 100644
--- a/compiler/cgen.nim
+++ b/compiler/cgen.nim
@@ -574,11 +574,13 @@ proc loadDynamicLib(m: BModule, lib: PLib) =
   if lib.name == nil: internalError(m.config, "loadDynamicLib")
 
 proc mangleDynLibProc(sym: PSym): Rope =
+  # we have to build this as a single rope in order not to trip the
+  # optimization in genInfixCall
   if sfCompilerProc in sym.flags:
     # NOTE: sym.loc.r is the external name!
     result = rope(sym.name.s)
   else:
-    result = "Dl_$1_" % [rope(sym.id)]
+    result = rope(strutils.`%`("Dl_$1_", $sym.id))
 
 proc symInDynamicLib(m: BModule, sym: PSym) =
   var lib = sym.annex
diff --git a/tests/cpp/t8241.nim b/tests/cpp/t8241.nim
new file mode 100644
index 0000000000..8e98fda10a
--- /dev/null
+++ b/tests/cpp/t8241.nim
@@ -0,0 +1,7 @@
+discard """
+  targets: "cpp"
+  action: "compile"
+"""
+
+proc foo(): cstring {.importcpp: "", dynlib: "".}
+echo foo()