In ASSERT and friends, use all the expressions we are passed even if !DEBUG

Otherwise we may get unused variable warnings. GHC should optimise them
all out for us.

1 files changed, 7 insertions, 5 deletions

diff --git a/compiler/HsVersions.h b/compiler/HsVersions.h
index 0c41fa521e..fb47f7cba5 100644
--- a/compiler/HsVersions.h
+++ b/compiler/HsVersions.h
@@ -43,11 +43,13 @@ name = Util.global (value) :: IORef (ty); \
 #define ASSERTM(mbool) do { bool <- mbool; ASSERT(bool) return () }
 #define ASSERTM2(mbool,msg) do { bool <- mbool; ASSERT2(bool,msg) return () }
 #else
-#define ASSERT(e)      if False then error "ASSERT"  else
-#define ASSERT2(e,msg) if False then error "ASSERT2" else
-#define ASSERTM(e)
-#define ASSERTM2(e,msg)
-#define WARN(e,msg)    if False then error "WARN"    else
+-- We have to actually use all the variables we are given or we may get
+-- unused variable warnings when DEBUG is off.
+#define ASSERT(e)      if False && (not (e)) then panic "ASSERT" else
+#define ASSERT2(e,msg) if False && (not (e)) then pprPanic "ASSERT2" (msg) else
+#define ASSERTM(e)       do { let { _mbool = (e) } }
+#define ASSERTM2(e,msg)  do { let { _mbool = (e) }; when False (panic "ASSERTM2") }
+#define WARN(e,msg)    if False && (e) then pprPanic "WARN" msg else
 #endif
 
 -- This #ifndef lets us switch off the "import FastString"