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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/104019] Testsuite
 17_intro/headers/c++2020/stdc++_multiple_inclusion.cc failures
Date: Mon, 24 Jan 2022 12:23:02 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104019

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |---

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The warning is correct, because with -fno-exceptions the try-block expands =
to:

  if (__in.good())
    if (true)  // expanded from __try
      {
        // ...
      }
    if (false) // expanded from __catch(__cxxabiv1::__forced_unwind&)
      {
        // ...
      }
    if (false) // expanded from __catch(...)
      {
        // ...
      }

And as the warning says, the if (false) condition is indented as though par=
t of
the outer if-statement.

The code is actually fine, but it would break if we ever added an else to t=
he
outer if:

  if (__in.good())
    __try
      {
        // ...
      }
    __catch(__cxxabiv1::__forced_unwind&)
      {
        // ...
      }
    __catch(...)
      {
        // ...
      }
  else  // uh-oh, binds to the last __catch


It's probably safest to add braces around the try-block.=