https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116646
Bug ID: 116646
Summary: Compilation of code inside if constexpr with failed
condition.
Product: gcc
Version: 12.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: cas43 at cs dot stanford.edu
Target Milestone: ---
When compiling the following code (g++ -std=c++20 file.cpp):
static const int y=0;
void f() {if constexpr(y<0){static_assert(y<0);}}
I expect no errors, but I get the following diagnostic with gcc version 12.3.0
(Ubuntu 12.3.0-1ubuntu1~22.04):
a.cpp: In function ‘void f()’:
a.cpp:2:44: error: static assertion failed
2 | void f() {if constexpr(y<0){static_assert(y<0);}}
| ~^~
a.cpp:2:44: note: the comparison reduces to ‘(0 < 0)’
I get similar diagnostics with every compiler I have ready access to:
gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04)
gcc version 10.5.0 (Ubuntu 10.5.0-1ubuntu1~22.04)
Ubuntu clang version 15.0.7
Ubuntu clang version 14.0.0-1ubuntu1.1
Ubuntu clang version 13.0.1-2ubuntu2.2
Ubuntu clang version 12.0.1-19ubuntu3
Ubuntu clang version 11.1.0-6
This suggests a mistake in my own code, but I don't see it. My understanding
is that the "if constexpr" should fail and prevent compilation within its body.
Declaring y as "static constexpr" still fails. The static_assert can be
replaced with other types of errors, such as a call to a function call that
fails to match.
