Save-and-restore errno more carefully in libstdc++

* doc/xml/manual/diagnostics.xml: Document use of errno. * doc/html/*: Regenerate. * config/locale/generic/c_locale.cc (_Save_errno): New helper. (__convert_to_v): Use _Save_errno. * include/ext/string_conversions.h (__stoa): Only restore errno when it isn't set to non-zero. From-SVN: r228328
author: Jonathan Wakely <jwakely@redhat.com> 2015-10-01 12:23:39 +0100
committer: Jonathan Wakely <redi@gcc.gnu.org> 2015-10-01 12:23:39 +0100
commit: f14decafae0d1771e16498e693e7bf2f7058e88e (patch)
tree: a019470ff02af16e5d85abeda9ad9e5dc945f92f
parent: aabef2de2f99d4a67840480eddf224ca1b43320e (diff)
download: gcc-f14decafae0d1771e16498e693e7bf2f7058e88e.zip
gcc-f14decafae0d1771e16498e693e7bf2f7058e88e.tar.gz
gcc-f14decafae0d1771e16498e693e7bf2f7058e88e.tar.bz2
8 files changed, 70 insertions, 17 deletions
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index cc22cfa..4199ede 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,12 @@
+2015-10-01  Jonathan Wakely  <jwakely@redhat.com>
+
+	* doc/xml/manual/diagnostics.xml: Document use of errno.
+	* doc/html/*: Regenerate.
+	* config/locale/generic/c_locale.cc (_Save_errno): New helper.
+	(__convert_to_v): Use _Save_errno.
+	* include/ext/string_conversions.h (__stoa): Only restore errno when
+	it isn't set to non-zero.
+
 2015-09-30  François Dumont  <fdumont@gcc.gnu.org>
 	    Jonathan Wakely  <jwakely@redhat.com>
 
diff --git a/libstdc++-v3/config/locale/generic/c_locale.cc b/libstdc++-v3/config/locale/generic/c_locale.cc
index 6da5f22..8dfea6b 100644
--- a/libstdc++-v3/config/locale/generic/c_locale.cc
+++ b/libstdc++-v3/config/locale/generic/c_locale.cc
@@ -44,6 +44,16 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+  namespace
+  {
+    struct _Save_errno
+    {
+      _Save_errno() : _M_errno(errno) { errno = 0; }
+      ~_Save_errno() { if (errno == 0) errno = _M_errno; }
+      int _M_errno;
+    };
+  }
+
   template<>
     void
     __convert_to_v(const char* __s, float& __v, ios_base::iostate& __err,
@@ -59,7 +69,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       bool __overflow = false;
 
 #if !__FLT_HAS_INFINITY__
-      errno = 0;
+      const _Save_errno __save_errno;
 #endif
 
 #ifdef _GLIBCXX_HAVE_STRTOF
@@ -123,7 +133,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       char* __sanity;
 
 #if !__DBL_HAS_INFINITY__
-      errno = 0;
+      const _Save_errno __save_errno;
 #endif
 
       __v = strtod(__s, &__sanity);
@@ -167,7 +177,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       setlocale(LC_ALL, "C");
 
 #if !__LDBL_HAS_INFINITY__
-      errno = 0;
+      const _Save_errno __save_errno;
 #endif
 
 #if defined(_GLIBCXX_HAVE_STRTOLD) && !defined(_GLIBCXX_HAVE_BROKEN_STRTOLD)
diff --git a/libstdc++-v3/doc/html/manual/concept_checking.html b/libstdc++-v3/doc/html/manual/concept_checking.html
index df7f22f..a01957d 100644
--- a/libstdc++-v3/doc/html/manual/concept_checking.html
+++ b/libstdc++-v3/doc/html/manual/concept_checking.html
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Concept Checking</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="diagnostics.html" title="Chapter 5.  Diagnostics" /><link rel="prev" href="diagnostics.html" title="Chapter 5.  Diagnostics" /><link rel="next" href="utilities.html" title="Chapter 6.  Utilities" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Concept Checking</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="diagnostics.html">Prev</a> </td><th width="60%" align="center">Chapter 5. 
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Concept Checking</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="diagnostics.html" title="Chapter 5.  Diagnostics" /><link rel="prev" href="errno.html" title="Use of errno by the library" /><link rel="next" href="utilities.html" title="Chapter 6.  Utilities" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Concept Checking</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="errno.html">Prev</a> </td><th width="60%" align="center">Chapter 5. 
   Diagnostics
   
 </th><td width="20%" align="right"> <a accesskey="n" href="utilities.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="std.diagnostics.concept_checking"></a>Concept Checking</h2></div></div></div><p>
@@ -41,10 +41,7 @@
    for example template argument types may need to be complete when used in
    a template definition, rather than at the point of instantiation.
    There are no plans to address these shortcomings.
- </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="diagnostics.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="diagnostics.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="utilities.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 5. 
-  Diagnostics
-  
- </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 6. 
+ </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="errno.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="diagnostics.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="utilities.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Use of errno by the library </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 6. 
   Utilities
   
 </td></tr></table></div></body></html>
 \ No newline at end of file
diff --git a/libstdc++-v3/doc/html/manual/diagnostics.html b/libstdc++-v3/doc/html/manual/diagnostics.html
index 30002b7..a90d5df 100644
--- a/libstdc++-v3/doc/html/manual/diagnostics.html
+++ b/libstdc++-v3/doc/html/manual/diagnostics.html
@@ -1,13 +1,13 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 5.  Diagnostics</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="std_contents.html" title="Part II.  Standard Contents" /><link rel="prev" href="termination.html" title="Termination" /><link rel="next" href="concept_checking.html" title="Concept Checking" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 5. 
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 5.  Diagnostics</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="std_contents.html" title="Part II.  Standard Contents" /><link rel="prev" href="termination.html" title="Termination" /><link rel="next" href="errno.html" title="Use of errno by the library" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 5. 
   Diagnostics
   
 </th></tr><tr><td width="20%" align="left"><a accesskey="p" href="termination.html">Prev</a> </td><th width="60%" align="center">Part II. 
     Standard Contents
-  </th><td width="20%" align="right"> <a accesskey="n" href="concept_checking.html">Next</a></td></tr></table><hr /></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="std.diagnostics"></a>Chapter 5. 
+  </th><td width="20%" align="right"> <a accesskey="n" href="errno.html">Next</a></td></tr></table><hr /></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="std.diagnostics"></a>Chapter 5. 
   Diagnostics
   <a id="id-1.3.4.3.1.1.1" class="indexterm"></a>
-</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions">Exceptions</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.api">API Reference</a></span></dt><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.data">Adding Data to <code class="classname">exception</code></a></span></dt></dl></dd><dt><span class="section"><a href="concept_checking.html">Concept Checking</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="std.diagnostics.exceptions"></a>Exceptions</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="std.diagnostics.exceptions.api"></a>API Reference</h3></div></div></div><p>
+</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions">Exceptions</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.api">API Reference</a></span></dt><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.data">Adding Data to <code class="classname">exception</code></a></span></dt></dl></dd><dt><span class="section"><a href="errno.html">Use of errno by the library</a></span></dt><dt><span class="section"><a href="concept_checking.html">Concept Checking</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="std.diagnostics.exceptions"></a>Exceptions</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="std.diagnostics.exceptions.api"></a>API Reference</h3></div></div></div><p>
       All exception objects are defined in one of the standard header
       files: <code class="filename">exception</code>,
       <code class="filename">stdexcept</code>, <code class="filename">new</code>, and
@@ -39,4 +39,4 @@
        int    e;
        DBID   id;     // some user-defined type
    };
-   </pre></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="termination.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="std_contents.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="concept_checking.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Termination </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Concept Checking</td></tr></table></div></body></html>
-\ No newline at end of file
+   </pre></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="termination.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="std_contents.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="errno.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Termination </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Use of errno by the library</td></tr></table></div></body></html>
+\ No newline at end of file
diff --git a/libstdc++-v3/doc/html/manual/index.html b/libstdc++-v3/doc/html/manual/index.html
index d48e49b..fbe657e 100644
--- a/libstdc++-v3/doc/html/manual/index.html
+++ b/libstdc++-v3/doc/html/manual/index.html
@@ -12,7 +12,7 @@
 </a></span></dt><dd><dl><dt><span class="section"><a href="support.html#std.support.types">Types</a></span></dt><dd><dl><dt><span class="section"><a href="support.html#std.support.types.fundamental">Fundamental Types</a></span></dt><dt><span class="section"><a href="support.html#std.support.types.numeric_limits">Numeric Properties</a></span></dt><dt><span class="section"><a href="support.html#std.support.types.null">NULL</a></span></dt></dl></dd><dt><span class="section"><a href="dynamic_memory.html">Dynamic Memory</a></span></dt><dt><span class="section"><a href="termination.html">Termination</a></span></dt><dd><dl><dt><span class="section"><a href="termination.html#support.termination.handlers">Termination Handlers</a></span></dt><dt><span class="section"><a href="termination.html#support.termination.verbose">Verbose Terminate Handler</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="diagnostics.html">5. 
   Diagnostics
   
-</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions">Exceptions</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.api">API Reference</a></span></dt><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.data">Adding Data to <code class="classname">exception</code></a></span></dt></dl></dd><dt><span class="section"><a href="concept_checking.html">Concept Checking</a></span></dt></dl></dd><dt><span class="chapter"><a href="utilities.html">6. 
+</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions">Exceptions</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.api">API Reference</a></span></dt><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.data">Adding Data to <code class="classname">exception</code></a></span></dt></dl></dd><dt><span class="section"><a href="errno.html">Use of errno by the library</a></span></dt><dt><span class="section"><a href="concept_checking.html">Concept Checking</a></span></dt></dl></dd><dt><span class="chapter"><a href="utilities.html">6. 
   Utilities
   
 </a></span></dt><dd><dl><dt><span class="section"><a href="utilities.html#std.util.functors">Functors</a></span></dt><dt><span class="section"><a href="pairs.html">Pairs</a></span></dt><dt><span class="section"><a href="memory.html">Memory</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#std.util.memory.allocator">Allocators</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#allocator.req">Requirements</a></span></dt><dt><span class="section"><a href="memory.html#allocator.design_issues">Design Issues</a></span></dt><dt><span class="section"><a href="memory.html#allocator.impl">Implementation</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#allocator.interface">Interface Design</a></span></dt><dt><span class="section"><a href="memory.html#allocator.default">Selecting Default Allocation Policy</a></span></dt><dt><span class="section"><a href="memory.html#allocator.caching">Disabling Memory Caching</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#allocator.using">Using a Specific Allocator</a></span></dt><dt><span class="section"><a href="memory.html#allocator.custom">Custom Allocators</a></span></dt><dt><span class="section"><a href="memory.html#allocator.ext">Extension Allocators</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#std.util.memory.auto_ptr">auto_ptr</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#auto_ptr.limitations">Limitations</a></span></dt><dt><span class="section"><a href="memory.html#auto_ptr.using">Use in Containers</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#std.util.memory.shared_ptr">shared_ptr</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#shared_ptr.req">Requirements</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.design_issues">Design Issues</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.impl">Implementation</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#shared_ptr.hier">Class Hierarchy</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.thread">Thread Safety</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.policy">Selecting Lock Policy</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.rel">Related functions and classes</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#shared_ptr.using">Use</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#shared_ptr.examples">Examples</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.issues">Unresolved Issues</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#shared_ptr.ack">Acknowledgments</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="traits.html">Traits</a></span></dt></dl></dd><dt><span class="chapter"><a href="strings.html">7. 
diff --git a/libstdc++-v3/doc/html/manual/std_contents.html b/libstdc++-v3/doc/html/manual/std_contents.html
index db4e46e..c7c6114 100644
--- a/libstdc++-v3/doc/html/manual/std_contents.html
+++ b/libstdc++-v3/doc/html/manual/std_contents.html
@@ -9,7 +9,7 @@
 </a></span></dt><dd><dl><dt><span class="section"><a href="support.html#std.support.types">Types</a></span></dt><dd><dl><dt><span class="section"><a href="support.html#std.support.types.fundamental">Fundamental Types</a></span></dt><dt><span class="section"><a href="support.html#std.support.types.numeric_limits">Numeric Properties</a></span></dt><dt><span class="section"><a href="support.html#std.support.types.null">NULL</a></span></dt></dl></dd><dt><span class="section"><a href="dynamic_memory.html">Dynamic Memory</a></span></dt><dt><span class="section"><a href="termination.html">Termination</a></span></dt><dd><dl><dt><span class="section"><a href="termination.html#support.termination.handlers">Termination Handlers</a></span></dt><dt><span class="section"><a href="termination.html#support.termination.verbose">Verbose Terminate Handler</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="diagnostics.html">5. 
   Diagnostics
   
-</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions">Exceptions</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.api">API Reference</a></span></dt><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.data">Adding Data to <code class="classname">exception</code></a></span></dt></dl></dd><dt><span class="section"><a href="concept_checking.html">Concept Checking</a></span></dt></dl></dd><dt><span class="chapter"><a href="utilities.html">6. 
+</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions">Exceptions</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.api">API Reference</a></span></dt><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.data">Adding Data to <code class="classname">exception</code></a></span></dt></dl></dd><dt><span class="section"><a href="errno.html">Use of errno by the library</a></span></dt><dt><span class="section"><a href="concept_checking.html">Concept Checking</a></span></dt></dl></dd><dt><span class="chapter"><a href="utilities.html">6. 
   Utilities
   
 </a></span></dt><dd><dl><dt><span class="section"><a href="utilities.html#std.util.functors">Functors</a></span></dt><dt><span class="section"><a href="pairs.html">Pairs</a></span></dt><dt><span class="section"><a href="memory.html">Memory</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#std.util.memory.allocator">Allocators</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#allocator.req">Requirements</a></span></dt><dt><span class="section"><a href="memory.html#allocator.design_issues">Design Issues</a></span></dt><dt><span class="section"><a href="memory.html#allocator.impl">Implementation</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#allocator.interface">Interface Design</a></span></dt><dt><span class="section"><a href="memory.html#allocator.default">Selecting Default Allocation Policy</a></span></dt><dt><span class="section"><a href="memory.html#allocator.caching">Disabling Memory Caching</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#allocator.using">Using a Specific Allocator</a></span></dt><dt><span class="section"><a href="memory.html#allocator.custom">Custom Allocators</a></span></dt><dt><span class="section"><a href="memory.html#allocator.ext">Extension Allocators</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#std.util.memory.auto_ptr">auto_ptr</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#auto_ptr.limitations">Limitations</a></span></dt><dt><span class="section"><a href="memory.html#auto_ptr.using">Use in Containers</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#std.util.memory.shared_ptr">shared_ptr</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#shared_ptr.req">Requirements</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.design_issues">Design Issues</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.impl">Implementation</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#shared_ptr.hier">Class Hierarchy</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.thread">Thread Safety</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.policy">Selecting Lock Policy</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.rel">Related functions and classes</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#shared_ptr.using">Use</a></span></dt><dd><dl><dt><span class="section"><a href="memory.html#shared_ptr.examples">Examples</a></span></dt><dt><span class="section"><a href="memory.html#shared_ptr.issues">Unresolved Issues</a></span></dt></dl></dd><dt><span class="section"><a href="memory.html#shared_ptr.ack">Acknowledgments</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="traits.html">Traits</a></span></dt></dl></dd><dt><span class="chapter"><a href="strings.html">7. 
diff --git a/libstdc++-v3/doc/xml/manual/diagnostics.xml b/libstdc++-v3/doc/xml/manual/diagnostics.xml
index 88ed2e2..67620e2 100644
--- a/libstdc++-v3/doc/xml/manual/diagnostics.xml
+++ b/libstdc++-v3/doc/xml/manual/diagnostics.xml
@@ -71,6 +71,39 @@
   </section>
 </section>
 
+<section xml:id="std.diagnostics.errno" xreflabel="errno"><info><title>Use of errno by the library</title></info>
+  <?dbhtml filename="errno.html"?>
+
+  <para>
+    The C and POSIX standards guarantee that <varname>errno</varname>
+    is never set to zero by any library function.
+    The C++ standard has less to say about when <varname>errno</varname>
+    is or isn't set, but libstdc++ follows the same rule and never sets
+    it to zero.
+  </para>
+
+  <para>
+    On the other hand, there are few guarantees about when the C++ library
+    sets <varname>errno</varname> on error, beyond what is specified for
+    functions that come from the C library.
+    For example, when <function>std::stoi</function> throws an exception of
+    type <classname>std::out_of_range</classname>, <varname>errno</varname>
+    may or may not have been set to <constant>ERANGE</constant>.
+  </para>
+
+  <para>
+    Parts of the C++ library may be implemented in terms of C library
+    functions, which may result in <varname>errno</varname> being set
+    with no explicit call to a C function. For example, on a target where
+    <function>operator new</function> uses <function>malloc</function>
+    a failed memory allocation with <function>operator new</function> might
+    set <varname>errno</varname> to <constant>ENOMEM</constant>.
+    Which C++ library functions can set <varname>errno</varname> in this way
+    is unspecified because it may vary between platforms and between releases.
+  </para>
+
+</section>
+
 <section xml:id="std.diagnostics.concept_checking" xreflabel="Concept Checking"><info><title>Concept Checking</title></info>
   <?dbhtml filename="concept_checking.html"?>
   
diff --git a/libstdc++-v3/include/ext/string_conversions.h b/libstdc++-v3/include/ext/string_conversions.h
index 58387a2..7f37e69 100644
--- a/libstdc++-v3/include/ext/string_conversions.h
+++ b/libstdc++-v3/include/ext/string_conversions.h
@@ -58,8 +58,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _Ret __ret;
 
       _CharT* __endptr;
-      const int __saved_errno = errno;
-      errno = 0;
+
+      struct _Save_errno {
+	_Save_errno() : _M_errno(errno) { errno = 0; }
+	~_Save_errno() { if (errno == 0) errno = _M_errno; }
+	int _M_errno;
+      } const __save_errno;
+
       const _TRet __tmp = __convf(__str, &__endptr, __base...);
 
       if (__endptr == __str)
@@ -71,7 +76,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	std::__throw_out_of_range(__name);
       else
 	__ret = __tmp;
-      errno = __saved_errno;
 
       if (__idx)
 	*__idx = __endptr - __str;
author	Jonathan Wakely <jwakely@redhat.com>	2015-10-01 12:23:39 +0100
committer	Jonathan Wakely <redi@gcc.gnu.org>	2015-10-01 12:23:39 +0100
commit	f14decafae0d1771e16498e693e7bf2f7058e88e (patch)
tree	a019470ff02af16e5d85abeda9ad9e5dc945f92f
parent	aabef2de2f99d4a67840480eddf224ca1b43320e (diff)
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