testsuite: Add test for #18527

testsuite/tests/codeGen/should_run/T18527.hs

+{-# LANGUAGE ForeignFunctionInterface #-}
+
+module Main where
+
+import Data.Bits (setBit)
+import Data.Word (Word32)
+import Data.Int (Int64)
+
+main :: IO ()
+main = offending 100 0 1
+
+offending :: Int64 -> Int64 -> Word32 -> IO ()
+offending h i id = do
+    oldMask <- sendMessage h (2245) i 0
+    let newMask = setBit oldMask (fromIntegral id)
+    sendMessage h (2244) i newMask
+    return ()
+
+foreign import ccall "func"
+    sendMessage :: Int64 -> Word32 -> Int64 -> Int64 -> IO Int64

testsuite/tests/codeGen/should_run/T18527.stdout

+ffi call
+ffi call
+

testsuite/tests/codeGen/should_run/T18527FFI.c

+#include <stdio.h>
+#include <stdint.h>
+
+int64_t func(int64_t a, uint32_t b, int64_t c, int64_t d) {
+    printf("ffi call");
+    if (a == 1) {
+        printf(" with corrupted convention\n");
+    }
+    else {
+        printf("\n");
+    }
+    return 0;
+}
+

testsuite/tests/codeGen/should_run/all.T

@@ -205,3 +205,4 @@ test('T16449_2', exit_code(0), compile_and_run, [''])
 test('T16846', [only_ways(['optasm']), exit_code(1)], compile_and_run, [''])
 
 test('T17920', cmm_src, compile_and_run, [''])
+test('T18527', normal, compile_and_run, ['T18527FFI.c'])