[Bug c++/87207] New: ODR issue with static functions and lambda templates

[blastrock at free dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87207

            Bug ID: 87207
           Summary: ODR issue with static functions and lambda templates
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: blastrock at free dot fr
  Target Milestone: ---

Created attachment 44652
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44652&action=edit
Small reproduction test case

I have a library that instantiates a chain of class templates and lambda
templates. I have two files with a static function that has the same name, but
by being static they should not interfere with each other.

It seems that gcc generates and exports a symbol depending on this static
function, and the linker only keeps one instance of it, making the other
instantiation wrong.

I have prepared a small reproduction test case. The String class is initialized
to 0 and asserts that it still contains 0 in its destructor. Moreover, it
prints the addresses where it is constructed and destroyed.

When compiling this project with any GCC version from Ubuntu (tested on Ubuntu
18.04, with GCC 6, 7 and 8), it will crash. I couldn't reproduce the issue on
Debian. I tried adding the stack-protector and fortify flags that are enabled
by default on Ubuntu but couldn't reproduce the bug on Debian.

The output is:

new 0x7ffcb217a6a8
new 0x7ffcb217a648
delete 0x7ffcb217a660
terminate called after throwing an instance of 'int'
Aborted (core dumped)

Removing the `async_resumable` instantiation from bunny.cpp (which is code that
is never called) will make main.cpp work.

The test case is attached.