xgupta added a comment.
In D155457#4511652 <https://reviews.llvm.org/D155457#4511652>, @aaron.ballman
wrote:
> In the x86 compilation: `sizeof(std::size_t) < sizeof(uint64_t)` is true, so
> we test the other expression; because `Size` is greater than `__SIZE_MAX__`
> the function returns false and the second static assertion fails as expected.
> In the x64 compilation: `sizeof(std::size_t) < sizeof(uint64_t)` is false
> (first static assertion fails) so we shouldn't even be evaluating the RHS of
> the `&&` to see if it's tautological because it can't contribute to the
> expression result, right?
Yes, I agree with both statements but what is odd in current behavior?
It seems to me uint64_t is unsigned long in <cstdint>, not unsigned long long
so the new test added in this patch (with `typedef unsigned long uint64_t`) is
now passing.
Behavior when the patch is applied-
$ ./bin/clang++ -Wall -fsyntax-only test.cpp -m64 -Wtype-limits
test.cpp:8:11: warning: result of comparison 'uint64_t' (aka 'unsigned long
long') > 18446744073709551615 is always false
[-Wtautological-type-limit-compare]
8 | Size > static_cast<uint64_t>(__SIZE_MAX__)) // no-warning
| ~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test.cpp:13:15: error: static assertion failed due to requirement
'sizeof(unsigned long) < sizeof(unsigned long long)':
13 | static_assert(sizeof(std::size_t) < sizeof(uint64_t), "");
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test.cpp:13:35: note: expression evaluates to '8 < 8'
13 | static_assert(sizeof(std::size_t) < sizeof(uint64_t), "");
| ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
1 warning and 1 error generated.
$ ./bin/clang++ -Wall -fsyntax-only test1.cpp -m64 -Wtype-limits
test1.cpp:12:15: error: static assertion failed due to requirement
'sizeof(unsigned long) < sizeof(unsigned long)':
12 | static_assert(sizeof(std::size_t) < sizeof(uint64_t), "");
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test1.cpp:12:35: note: expression evaluates to '8 < 8'
12 | static_assert(sizeof(std::size_t) < sizeof(uint64_t), "");
| ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
1 error generated.
where test.cpp using wrapper and test1.cpp is using standard headers.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D155457/new/
https://reviews.llvm.org/D155457
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