Public bug reported:
BACKGROUND
Simple code involving coroutines results in internal compiler errors in
the version of gcc provided by this package. I am filing a bug report
here because gcc version 10.1 does not produce these errors, and these
errors are only present in the compiler version provided by the gcc-10
package.
On my system, this version is:
g++-10 (Ubuntu 10-20200411-0ubuntu1) 10.0.1 20200411 (experimental)
[master revision
bb87d5cc77d:75961caccb7:f883c46b4877f637e0fa5025b4d6b5c9040ec566]
REPRODUCING THE BUG
In order to reproduce the bug, create a file main.cpp and compile as:
g++-10 -std=c++20 -fcoroutines main.cpp
Compiling this file will produce an internal compiler error. Here, g++-10
invokes the g++ compiler provided by this package. This file should contain the
following code (code inside ticks):
```
#include <coroutine>
#include <exception>
// Compiler version resulting in bug: gcc 10.0.1 20200411 (experimental)
// Compile with:
// g++-10 -std=c++20 -fcoroutines main.cpp
struct promise {
std::suspend_never initial_suspend() { return {}; }
std::suspend_never final_suspend() { return {}; }
void return_void() {}
bool get_return_object() { return true; }
static bool get_return_object_on_allocation_failure() { return false; }
[[noreturn]] void unhandled_exception() { std::terminate(); }
};
struct result {
bool success;
result(bool success) : success(success) {}
using promise_type = promise;
};
result foo() {
co_return;
}
int main() {
foo();
}
```
Under the version of gcc provided by this package, the output of
compilation is:
during RTL pass: expand
main.cpp: In function ‘result foo()’:
main.cpp:25:1: internal compiler error: in expand_expr_addr_expr_1, at
expr.c:8070
25 | }
| ^
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-10/README.Bugs> for instructions.
Internal compiler errors such as these were fixed in gcc 10.1. Here is a
link to Compiler Explorer demonstrating that it compiles fine under
10.1: https://godbolt.org/z/dMrY8r
There are many similar code examples that result in internal compiler
errors, and I believe the occurrence of these errors will be frustrating
for anyone attempting to use C++20 features such as coroutines. In
addition, some code examples (such as the one above) only produce a
compiler error when there's no optimization flag, but compile fine with
optimization enabled. This is extremely unexpected behavior.
** Affects: gcc-10 (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1887338
Title:
The gcc provided by gcc-10 package produces internal compiler errors
not present in gcc version 10.1
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