From 24316d315b561255e328ff0afc71d2a45e0a8b0f Mon Sep 17 00:00:00 2001
From: Devin Lehmacher <lehmacdj@gmail.com>
Date: Tue, 4 Feb 2025 22:41:13 -0500
Subject: [PATCH] Fix handling of void parameters passed to functions

---
 inline-c/src/Language/C/Inline/Context.hs      | 7 +++++++
 inline-c/test/Language/C/Inline/ContextSpec.hs | 4 ++++
 2 files changed, 11 insertions(+)

diff --git a/inline-c/src/Language/C/Inline/Context.hs b/inline-c/src/Language/C/Inline/Context.hs
index 42d12ed..9284477 100644
--- a/inline-c/src/Language/C/Inline/Context.hs
+++ b/inline-c/src/Language/C/Inline/Context.hs
@@ -320,10 +320,17 @@ convertType purity cTypes = runMaybeT . go
         -- We cannot convert standalone prototypes
         mzero
 
+    buildArr :: [TH.Type] -> TH.Type -> TH.Q TH.Type
     buildArr [] hsRetType =
       case purity of
         Pure -> [t| $(return hsRetType) |]
         IO -> [t| IO $(return hsRetType) |]
+    buildArr [TH.TupleT 0] hsRetType =
+      case purity of
+        Pure -> [t| $(return hsRetType) |]
+        IO -> [t| IO $(return hsRetType) |]
+    buildArr (TH.TupleT 0 : hsPars) hsRetType =
+      fail "C function can only have void parameter as the only parameter"
     buildArr (hsPar : hsPars) hsRetType =
       [t| $(return hsPar) -> $(buildArr hsPars hsRetType) |]
 
diff --git a/inline-c/test/Language/C/Inline/ContextSpec.hs b/inline-c/test/Language/C/Inline/ContextSpec.hs
index ef3c5f2..71aa754 100644
--- a/inline-c/test/Language/C/Inline/ContextSpec.hs
+++ b/inline-c/test/Language/C/Inline/ContextSpec.hs
@@ -74,6 +74,10 @@ spec = do
     shouldBeType
       (cty "int (*f)(unsigned char, float)")
       [t| FunPtr (CUChar -> CFloat -> IO CInt) |]
+  Hspec.it "converts void parameter function pointer" $ do
+    shouldBeType 
+      (cty "void (*f)(void)") 
+      [t| FunPtr (IO ()) |]
   Hspec.it "converts complicated function pointers (1)" $ do
     -- pointer to function returning pointer to function returning int
     shouldBeType