The following test case compiles via GCC with no errors or warnings, but
generates a type warning with sparse:
void f(void);
void f(void)
{
const int *pc;
typeof(*pc) *pc2 = pc;
}
Sparse says:
typeof-const.c:5:24: warning: incorrect type in initializer (different modifiers)
typeof-const.c:5:24: expected int *pc2
typeof-const.c:5:24: got int const *pc
Since pc has type "const int *", "typeof(*pc) *" should also have type
"const int *", not "int *".
The actual use case for which this came up occurred in the kernel when
using the equivalent of:
typeof(*p) __attribute__((address_space(0),force)) *
to generate the same type as p but in address space 0 rather than
whatever address space p had. That worked fine for non-const pointers,
but const pointers lost their constness, resulting in constness
warnings.
The following patch adds a test case for this; please apply once sparse
handles this case correctly:
---------->8----------
From: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Subject: [PATCH] validation: Add new test case for typeof(*ptr) preserving const
If ptr has type "const foo *", then "typeof(*ptr) *" should also have
type "const foo *", not "foo *". Add a test to ensure that.
Signed-off-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
---
validation/typeof-const.c | 9 +++++++++
1 file changed, 9 insertions(+)
create mode 100644 validation/typeof-const.c
diff --git a/validation/typeof-const.c b/validation/typeof-const.c
new file mode 100644
index 0000000..d02d39a
--- /dev/null
+++ b/validation/typeof-const.c
@@ -0,0 +1,9 @@
+void f(void);
+void f(void)
+{
+ const int *pc;
+ typeof(*pc) *pc2 = pc;
+}
+/*
+ * check-name: typeof-const.c
+ */
--
1.8.4.rc3
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