https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121647
Bug ID: 121647
Summary: template for: can't contain case labels for
surrounding switch
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ivan.lazaric.gcc at gmail dot com
Target Milestone: ---
https://godbolt.org/z/9Tj9enaxK
Code:
```
template<auto> void blah();
void use(int x){
switch (x){
template for (constexpr int y : {1,2,3}){
case y: { blah<y>(); break; }
}
default: break;
}
}
```
Compiled with flags: -std=c++26 -O3
(though -O3 shouldn't matter)
This fails to compile with error:
```
<source>: In function 'void use(int)':
<source>:8:18: error: jump to case label
8 | case y: { blah<y>(); break; }
| ^
<source>:7:9: note: enters 'template for' statement
7 | template for (constexpr int y : {1,2,3}){
| ^~~~~~~~
<source>:7:37: warning: statement will never be executed [-Wswitch-unreachable]
7 | template for (constexpr int y : {1,2,3}){
| ^
```
What I expected:
I expected the code to compile, and be functionally equivalent to:
```
template<auto> void blah();
void use(int x){
switch (x){
case 1: { blah<1>(); break; }
case 2: { blah<2>(); break; }
case 3: { blah<3>(); break; }
default: break;
}
}
```
Whether or not the standard supports my expectations I am unsure
Just noting same code compiles with the experimental clang implementation:
https://godbolt.org/z/snfG7qqKh
