[gcc r13-4098] libstdc++: Fix stream initialization with static library [PR107701]

[gcc r13-4098] libstdc++: Fix stream initialization with static library [PR107701]

[Patrick Palka]

https://gcc.gnu.org/g:ec59848074ba8c4310cbadb603822bfaeff03a32

commit r13-4098-gec59848074ba8c4310cbadb603822bfaeff03a32
Author: Patrick Palka <ppalka@redhat.com>
Date:   Wed Nov 16 08:53:51 2022 -0500

    libstdc++: Fix stream initialization with static library [PR107701]
    
    When linking with a static library, the linker seems to discard a
    constituent .o object (including its global initializers) if nothing
    defined in the object is referenced by the program (unless e.g.
    --whole-archive is used).  This behavior breaks iostream with static
    libstdc++.a (on systems that support init priorities) because we define
    the global initializer for the standard stream objects in a separate TU
    (ios_init.cc) from the stream object definitions (globals_io.cc).
    
    This patch fixes this by moving the stream initialization object into
    the same TU that defines the stream objects, so that any use of the
    streams prevents the linker from discarding this global initializer.
    
            PR libstdc++/107701
    
    libstdc++-v3/ChangeLog:
    
            * include/std/iostream (__ioinit): Adjust comment.
            * src/c++98/globals_io.cc: Include "io_base_init.h" here
            instead of ...
            * src/c++98/ios_init.cc: ... here.
            * src/c++98/ios_base_init.h (__ioinit): More comments.
            * testsuite/17_intro/static.cc: dg-do run instead of just link.

Diff:
---
 libstdc++-v3/include/std/iostream         | 2 +-
 libstdc++-v3/src/c++98/globals_io.cc      | 2 ++
 libstdc++-v3/src/c++98/ios_base_init.h    | 1 +
 libstdc++-v3/src/c++98/ios_init.cc        | 2 --
 libstdc++-v3/testsuite/17_intro/static.cc | 2 +-
 5 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/include/std/iostream b/libstdc++-v3/include/std/iostream
index ff78e1cfb87..0c62e9aeb7f 100644
--- a/libstdc++-v3/include/std/iostream
+++ b/libstdc++-v3/include/std/iostream
@@ -74,7 +74,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   // For construction of filebuffers for cout, cin, cerr, clog et. al.
   // When the init_priority attribute is usable, we do this initialization
-  // in the compiled library instead (src/c++98/ios_init.cc).
+  // in the compiled library instead (src/c++98/globals_io.cc).
 #if !__has_attribute(__init_priority__)
   static ios_base::Init __ioinit;
 #endif
diff --git a/libstdc++-v3/src/c++98/globals_io.cc b/libstdc++-v3/src/c++98/globals_io.cc
index 04fecb22aeb..bfd808b5bbd 100644
--- a/libstdc++-v3/src/c++98/globals_io.cc
+++ b/libstdc++-v3/src/c++98/globals_io.cc
@@ -69,6 +69,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   fake_wostream wclog;
 #endif
 
+#include "ios_base_init.h"
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
 
diff --git a/libstdc++-v3/src/c++98/ios_base_init.h b/libstdc++-v3/src/c++98/ios_base_init.h
index 1c71038f4a1..b600ec3298e 100644
--- a/libstdc++-v3/src/c++98/ios_base_init.h
+++ b/libstdc++-v3/src/c++98/ios_base_init.h
@@ -7,6 +7,7 @@
 // sufficiently early (so that it happens before any other global
 // constructor when statically linking with libstdc++.a), instead of
 // doing so in (each TU that includes) <iostream>.
+// This needs to be done in the same TU that defines the stream objects.
 #if __has_attribute(init_priority)
 static ios_base::Init __ioinit __attribute__((init_priority(90)));
 #endif
diff --git a/libstdc++-v3/src/c++98/ios_init.cc b/libstdc++-v3/src/c++98/ios_init.cc
index 4016fcab785..1b5132f1c2d 100644
--- a/libstdc++-v3/src/c++98/ios_init.cc
+++ b/libstdc++-v3/src/c++98/ios_init.cc
@@ -75,8 +75,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   extern wostream wclog;
 #endif
 
-#include "ios_base_init.h"
-
   ios_base::Init::Init()
   {
     if (__gnu_cxx::__exchange_and_add_dispatch(&_S_refcount, 1) == 0)
diff --git a/libstdc++-v3/testsuite/17_intro/static.cc b/libstdc++-v3/testsuite/17_intro/static.cc
index ffa7ecb7077..a0d6ed081f8 100644
--- a/libstdc++-v3/testsuite/17_intro/static.cc
+++ b/libstdc++-v3/testsuite/17_intro/static.cc
@@ -1,4 +1,4 @@
-// { dg-do link { target c++11 } }
+// { dg-do run { target c++11 } }
 // { dg-require-static-libstdcxx }
 // { dg-options "-static-libstdc++" }