From dd8cbf5fca7becf43b5cec07ecf7e579308e2e7a Mon Sep 17 00:00:00 2001
From: Araq <rumpf_a@web.de>
Date: Fri, 17 Feb 2017 17:44:52 +0100
Subject: [PATCH] fixes #5404

---
 compiler/ccgtypes.nim           |  8 +++++++-
 tests/ccgbugs/tmangle_field.nim | 16 ++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 tests/ccgbugs/tmangle_field.nim

diff --git a/compiler/ccgtypes.nim b/compiler/ccgtypes.nim
index e30fe5598b..29d4e23c97 100644
--- a/compiler/ccgtypes.nim
+++ b/compiler/ccgtypes.nim
@@ -24,7 +24,13 @@ proc isKeyword(w: PIdent): bool =
 
 proc mangleField(m: BModule; name: PIdent): string =
   result = mangle(name.s)
-  if isKeyword(name) or m.g.config.cppDefines.contains(result):
+  # fields are tricky to get right and thanks to generic types producing
+  # duplicates we can end up mangling the same field multiple times. However
+  # if we do so, the 'cppDefines' table might be modified in the meantime
+  # meaning we produce inconsistent field names (see bug #5404).
+  # Hence we do not check for ``m.g.config.cppDefines.contains(result)`` here
+  # anymore:
+  if isKeyword(name):
     result.add "_0"
 
 when false:
diff --git a/tests/ccgbugs/tmangle_field.nim b/tests/ccgbugs/tmangle_field.nim
new file mode 100644
index 0000000000..9e4012b8b1
--- /dev/null
+++ b/tests/ccgbugs/tmangle_field.nim
@@ -0,0 +1,16 @@
+discard """
+"""
+
+# bug #5404
+
+import parseopt2
+
+{.emit: """typedef struct {
+    int key;
+} foo;""".}
+
+type foo* {.importc: "foo", nodecl.} = object
+  key* {.importc: "key".}: cint
+
+for kind, key, value in parseopt2.getopt():
+  discard