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* [Bug c++/96557] New: Diagnostics: Can you tell me why it's not a constant expression?
@ 2020-08-10 16:25 barry.revzin at gmail dot com
2020-08-10 16:40 ` [Bug c++/96557] " mpolacek at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: barry.revzin at gmail dot com @ 2020-08-10 16:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96557
Bug ID: 96557
Summary: Diagnostics: Can you tell me why it's not a constant
expression?
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: barry.revzin at gmail dot com
Target Milestone: ---
Consider:
struct X {
char storage[100] = {};
char const* head = storage;
};
void f() {
constexpr X x = {};
}
gcc correctly rejects this with:
error: 'X{"", ((const char*)(& x.X::storage))}' is not a constant expression
7 | constexpr X x = {};
| ^
It'd be great if the error here actually indicated _why_ it's not a constant
expression (or how to fix it). clang does a little bit better:
<source>:7:17: error: constexpr variable 'x' must be initialized by a constant
expression
constexpr X x = {};
^ ~~
<source>:7:17: note: pointer to subobject of 'x' is not a constant expression
<source>:7:17: note: declared here
But ideally we get some message about specifically 'head' pointing to 'storage'
and a fixup suggesting making the variable x static.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug c++/96557] Diagnostics: Can you tell me why it's not a constant expression?
2020-08-10 16:25 [Bug c++/96557] New: Diagnostics: Can you tell me why it's not a constant expression? barry.revzin at gmail dot com
@ 2020-08-10 16:40 ` mpolacek at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2020-08-10 16:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96557
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Keywords| |diagnostic
CC| |mpolacek at gcc dot gnu.org
Last reconfirmed| |2020-08-10
--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
That would be great to have.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-08-10 16:25 [Bug c++/96557] New: Diagnostics: Can you tell me why it's not a constant expression? barry.revzin at gmail dot com
2020-08-10 16:40 ` [Bug c++/96557] " mpolacek at gcc dot gnu.org
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