This series contains fixes for several problems related
to the base type of enums (maybe better known as the
underlying type). One of the symptoms is invalid warnings
about truncated constants:
"cast truncates bits from constant value (8000000000000000 becomes 0)"
With this series, the rules for an enum's base type become:
1) if all enumerators are of the same restricted type,
then the base type is this restricted type
2) if all the enumerators have an (non-restricted)
integer type, then the base type will be the
smallest integer type at least as big as 'int' and
able to hold all the values of the enum (so, first
int, unsigned int, long, unsigned int, ...).
3) an enumerator without initializer is considered as
being a non-restricted type.
4) non-integer or non-constant initializers are invalid
5) temporary, if the enumerators mix restricted and
non-restricted types, each enumerator keep their
original type and a warning is issued.
Note: This is to keep compatibility with (a few)
such uses in the kernel.
6) otherwise, the enum is invalid.
The differences with GCC are:
a) GCC favor unsigned types for enum's base types
b) irrespectively of a) GCC force to 'int' enumerators
that fit in a int (the justification being to avoid
promotions to unsigned types when comparing such
enumerators with (signed) integers).
So, yes, an enumerator will either have the same type
as the enum base type or 'int' if it fit in an 'int'.
This series is available for review & testing in the Git repository at:
git://github.com/lucvoo/sparse-dev.git fix-enum-type
for you to fetch changes up to 19483120177ae37f3780ca8e9fa7c211717e2ad3:
enum: rewrite bound checking (2018-09-08 00:43:24 +0200)
----------------------------------------------------------------
Luc Van Oostenryck (12):
doc: is_int_type() returns false for SYM_RESTRICTs
enum: add testcase for UB in oversized shift
enum: fix UB when rshifting by full width
enum: add testcase for type of enum members
enum: add testcase for base & enumerator type
enum: fix cast_enum_list()
enum: use the smallest type that fit
enum: use the values to determine the base type
enum: only warn (once) when mixing bitwiseness
enum: warn when mixing different restricted types
enum: warn on bad enums
enum: rewrite bound checking
parse.c | 118 +++++++++++++++++++--------------------
symbol.h | 5 ++
validation/bug-rshift-ub.c | 16 ++++++
validation/enum-base-type.c | 28 ++++++++++
validation/enum-bitwise-bad.c | 20 +++++++
validation/enum-bitwise-mixed.c | 29 ++++++++++
validation/enum-bitwise.c | 19 +++++++
validation/enum-bounds.c | 23 ++++++++
validation/enum-init-constness.c | 9 +++
validation/enum-invalid.c | 11 ++++
validation/enum-min-size.c | 29 ++++++++++
validation/enum-same-type.c | 14 +++++
validation/enum-sign-gcc.c | 63 +++++++++++++++++++++
validation/enum-typecheck.c | 39 +++++++++++++
14 files changed, 362 insertions(+), 61 deletions(-)
create mode 100644 validation/bug-rshift-ub.c
create mode 100644 validation/enum-base-type.c
create mode 100644 validation/enum-bitwise-bad.c
create mode 100644 validation/enum-bitwise-mixed.c
create mode 100644 validation/enum-bitwise.c
create mode 100644 validation/enum-bounds.c
create mode 100644 validation/enum-init-constness.c
create mode 100644 validation/enum-invalid.c
create mode 100644 validation/enum-min-size.c
create mode 100644 validation/enum-same-type.c
create mode 100644 validation/enum-sign-gcc.c
create mode 100644 validation/enum-typecheck.c
