https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104514
Bug ID: 104514
Summary: add feature to create a pointer to a fixed address as
constexpr
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: goswin-v-b at web dot de
Target Milestone: ---
In the embedded and micro controller world memory mapped registers are very
common. They can be declared as external object and fudged in using linker
scripts, which prevents a lot of optimizations. Or they can be declared as
pointers, in the most reduced form like this:
int *p = (int*)0x12345678;
My problem now is that this isn't a constexpr and can't be used in any
constexpr code:
foo.cc:1:20: error: ‘reinterpret_cast’ from integer to pointer
1 | constexpr int *p = (int*)0x12345678;
| ^~~~~~~~~~~~~~~~
While this is the right thing in general there should be a way to allow this
special case. A way to tell the compiler that an object exists at a fixed
address and still be a constexpr.
