2022-02-04 19:45:03

by Ian Abbott

Subject: [PATCH] typecheck.h: Force a compilation error if typecheck(type,x) fails

Calling the `typecheck(type,x)` macro emits a compiler warning if the
type of `x` is incompatible with type `type`. Change it to force a
compilation error instead.

Signed-off-by: Ian Abbott <[email protected]>
---
include/linux/typecheck.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/typecheck.h b/include/linux/typecheck.h
index 46b15e2aaefb..c9125304f6ba 100644
--- a/include/linux/typecheck.h
+++ b/include/linux/typecheck.h
@@ -2,14 +2,15 @@
#ifndef TYPECHECK_H_INCLUDED
#define TYPECHECK_H_INCLUDED

+#include <linux/compiler_types.h>
+#include <linux/build_bug.h>
+
/*
* Check at compile time that something is of a particular type.
* Always evaluates to 1 so you may use it easily in comparisons.
*/
#define typecheck(type,x) \
-({ type __dummy; \
- typeof(x) __dummy2; \
- (void)(&__dummy == &__dummy2); \
+({ BUILD_BUG_ON(!__same_type(type, (x))); \
1; \
})

--
2.34.1

2022-06-24 11:15:41

by Ian Abbott

Subject: [RESEND PATCH] typecheck.h: Force a compilation error if typecheck(type,x) fails

Calling the `typecheck(type,x)` macro emits a compiler warning if the
type of `x` is incompatible with type `type`. Change it to force a
compilation error instead.

Signed-off-by: Ian Abbott <[email protected]>
---
include/linux/typecheck.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/typecheck.h b/include/linux/typecheck.h
index 46b15e2aaefb..c9125304f6ba 100644
--- a/include/linux/typecheck.h
+++ b/include/linux/typecheck.h
@@ -2,14 +2,15 @@
#ifndef TYPECHECK_H_INCLUDED
#define TYPECHECK_H_INCLUDED

+#include <linux/compiler_types.h>
+#include <linux/build_bug.h>
+
/*
* Check at compile time that something is of a particular type.
* Always evaluates to 1 so you may use it easily in comparisons.
*/
#define typecheck(type,x) \
-({ type __dummy; \
- typeof(x) __dummy2; \
- (void)(&__dummy == &__dummy2); \
+({ BUILD_BUG_ON(!__same_type(type, (x))); \
1; \
})

--
2.35.1