app-admin/lnav: Backport to build with gcc-11

This commit partially[0] backports a patch from upstream[1][2] to
allow lnav to build with gcc-11.

This patch was tested with gcc-10.2.0-r5 and gcc-11.1.0.

[0] Only the changes to m4/ax_cxx_compile_stdcxx.m4 were necessary
    to address the gcc-11 fix.
[1] https://github.com/tstack/lnav/issues/864
[2] https://github.com/tstack/lnav/commit/8f7b08c9c5d1b30ca2b91dbfdb13f4dfa5326f95

Closes: https://bugs.gentoo.org/786456
Package-Manager: Portage-3.0.18, Repoman-3.0.2
Signed-off-by: Randy Barlow <randy@electronsweatshop.com>
Closes: https://github.com/gentoo/gentoo/pull/20975
Signed-off-by: Sam James <sam@gentoo.org>

2 files changed, 564 insertions, 0 deletions

diff --git a/app-admin/lnav/files/lnav-0.9.0-bug786456.patch b/app-admin/lnav/files/lnav-0.9.0-bug786456.patch
new file mode 100644
index 000000000000..e77dd17854e5
--- /dev/null
+++ b/app-admin/lnav/files/lnav-0.9.0-bug786456.patch
@@ -0,0 +1,561 @@
+From e6d2e2d2b95c27cc85397d4af9528111c5304d02 Mon Sep 17 00:00:00 2001
+From: Timothy Stack <timothyshanestack@gmail.com>
+Date: Sun, 30 May 2021 13:33:05 -0700
+Subject: [PATCH] [logfile] add notes for automatic decisions and fix compile
+ errors
+
+Fixes #864
+
+Signed-off-by: Randy Barlow <randy@electronsweatshop.com>
+---
+ m4/ax_cxx_compile_stdcxx.m4 | 462 +++++++++++++++++++++++++++++++++---
+ src/base/result.h           |   1 +
+ src/logfile.hh              |  13 +
+ src/optional.hpp            |  45 +++-
+ src/pcrepp/pcrepp.hh        |   1 +
+ 5 files changed, 482 insertions(+), 40 deletions(-)
+
+diff --git a/m4/ax_cxx_compile_stdcxx.m4 b/m4/ax_cxx_compile_stdcxx.m4
+index 2c18e49c..9413da62 100644
+--- a/m4/ax_cxx_compile_stdcxx.m4
++++ b/m4/ax_cxx_compile_stdcxx.m4
+@@ -1,5 +1,5 @@
+ # ===========================================================================
+-#   http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
++#  https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
+ # ===========================================================================
+ #
+ # SYNOPSIS
+@@ -16,7 +16,7 @@
+ #   The second argument, if specified, indicates whether you insist on an
+ #   extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
+ #   -std=c++11).  If neither is specified, you get whatever works, with
+-#   preference for an extended mode.
++#   preference for no added switch, and then for an extended mode.
+ #
+ #   The third argument, if specified 'mandatory' or if left unspecified,
+ #   indicates that baseline support for the specified C++ standard is
+@@ -33,21 +33,24 @@
+ #   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
+ #   Copyright (c) 2015 Paul Norman <penorman@mac.com>
+ #   Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
++#   Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com>
++#   Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com>
++#   Copyright (c) 2020 Jason Merrill <jason@redhat.com>
+ #
+ #   Copying and distribution of this file, with or without modification, are
+ #   permitted in any medium without royalty provided the copyright notice
+ #   and this notice are preserved.  This file is offered as-is, without any
+ #   warranty.
+ 
+-#serial 4
++#serial 12
+ 
+ dnl  This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
+ dnl  (serial version number 13).
+ 
+ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
+-  m4_if([$1], [11], [],
+-        [$1], [14], [],
+-        [$1], [17], [m4_fatal([support for C++17 not yet implemented in AX_CXX_COMPILE_STDCXX])],
++  m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"],
++        [$1], [14], [ax_cxx_compile_alternatives="14 1y"],
++        [$1], [17], [ax_cxx_compile_alternatives="17 1z"],
+         [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
+   m4_if([$2], [], [],
+         [$2], [ext], [],
+@@ -59,18 +62,21 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
+         [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
+   AC_LANG_PUSH([C++])dnl
+   ac_success=no
+-  AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
+-  ax_cv_cxx_compile_cxx$1,
+-  [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
+-    [ax_cv_cxx_compile_cxx$1=yes],
+-    [ax_cv_cxx_compile_cxx$1=no])])
+-  if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
+-    ac_success=yes
+-  fi
++
++  m4_if([$2], [], [dnl
++    AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
++		   ax_cv_cxx_compile_cxx$1,
++      [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
++        [ax_cv_cxx_compile_cxx$1=yes],
++        [ax_cv_cxx_compile_cxx$1=no])])
++    if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
++      ac_success=yes
++    fi])
+ 
+   m4_if([$2], [noext], [], [dnl
+   if test x$ac_success = xno; then
+-    for switch in -std=gnu++$1 -std=gnu++0x; do
++    for alternative in ${ax_cxx_compile_alternatives}; do
++      switch="-std=gnu++${alternative}"
+       cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
+       AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
+                      $cachevar,
+@@ -96,22 +102,27 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
+     dnl HP's aCC needs +std=c++11 according to:
+     dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
+     dnl Cray's crayCC needs "-h std=c++11"
+-    for switch in -std=c++$1 -std=c++0x +std=c++$1 "-h std=c++$1"; do
+-      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
+-      AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
+-                     $cachevar,
+-        [ac_save_CXX="$CXX"
+-         CXX="$CXX $switch"
+-         AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
+-          [eval $cachevar=yes],
+-          [eval $cachevar=no])
+-         CXX="$ac_save_CXX"])
+-      if eval test x\$$cachevar = xyes; then
+-        CXX="$CXX $switch"
+-        if test -n "$CXXCPP" ; then
+-          CXXCPP="$CXXCPP $switch"
++    for alternative in ${ax_cxx_compile_alternatives}; do
++      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
++        cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
++        AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
++                       $cachevar,
++          [ac_save_CXX="$CXX"
++           CXX="$CXX $switch"
++           AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
++            [eval $cachevar=yes],
++            [eval $cachevar=no])
++           CXX="$ac_save_CXX"])
++        if eval test x\$$cachevar = xyes; then
++          CXX="$CXX $switch"
++          if test -n "$CXXCPP" ; then
++            CXXCPP="$CXXCPP $switch"
++          fi
++          ac_success=yes
++          break
+         fi
+-        ac_success=yes
++      done
++      if test x$ac_success = xyes; then
+         break
+       fi
+     done
+@@ -148,6 +159,11 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
+   _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
+ )
+ 
++m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17],
++  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
++  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
++  _AX_CXX_COMPILE_STDCXX_testbody_new_in_17
++)
+ 
+ dnl  Tests for new features in C++11
+ 
+@@ -185,11 +201,13 @@ namespace cxx11
+ 
+     struct Base
+     {
++      virtual ~Base() {}
+       virtual void f() {}
+     };
+ 
+     struct Derived : public Base
+     {
++      virtual ~Derived() override {}
+       virtual void f() override {}
+     };
+ 
+@@ -518,7 +536,7 @@ namespace cxx14
+ 
+   }
+ 
+-  namespace test_digit_seperators
++  namespace test_digit_separators
+   {
+ 
+     constexpr auto ten_million = 100'000'000;
+@@ -560,3 +578,385 @@ namespace cxx14
+ #endif  // __cplusplus >= 201402L
+ 
+ ]])
++
++
++dnl  Tests for new features in C++17
++
++m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[
++
++// If the compiler admits that it is not ready for C++17, why torture it?
++// Hopefully, this will speed up the test.
++
++#ifndef __cplusplus
++
++#error "This is not a C++ compiler"
++
++#elif __cplusplus < 201703L
++
++#error "This is not a C++17 compiler"
++
++#else
++
++#include <initializer_list>
++#include <utility>
++#include <type_traits>
++
++namespace cxx17
++{
++
++  namespace test_constexpr_lambdas
++  {
++
++    constexpr int foo = [](){return 42;}();
++
++  }
++
++  namespace test::nested_namespace::definitions
++  {
++
++  }
++
++  namespace test_fold_expression
++  {
++
++    template<typename... Args>
++    int multiply(Args... args)
++    {
++      return (args * ... * 1);
++    }
++
++    template<typename... Args>
++    bool all(Args... args)
++    {
++      return (args && ...);
++    }
++
++  }
++
++  namespace test_extended_static_assert
++  {
++
++    static_assert (true);
++
++  }
++
++  namespace test_auto_brace_init_list
++  {
++
++    auto foo = {5};
++    auto bar {5};
++
++    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
++    static_assert(std::is_same<int, decltype(bar)>::value);
++  }
++
++  namespace test_typename_in_template_template_parameter
++  {
++
++    template<template<typename> typename X> struct D;
++
++  }
++
++  namespace test_fallthrough_nodiscard_maybe_unused_attributes
++  {
++
++    int f1()
++    {
++      return 42;
++    }
++
++    [[nodiscard]] int f2()
++    {
++      [[maybe_unused]] auto unused = f1();
++
++      switch (f1())
++      {
++      case 17:
++        f1();
++        [[fallthrough]];
++      case 42:
++        f1();
++      }
++      return f1();
++    }
++
++  }
++
++  namespace test_extended_aggregate_initialization
++  {
++
++    struct base1
++    {
++      int b1, b2 = 42;
++    };
++
++    struct base2
++    {
++      base2() {
++        b3 = 42;
++      }
++      int b3;
++    };
++
++    struct derived : base1, base2
++    {
++        int d;
++    };
++
++    derived d1 {{1, 2}, {}, 4};  // full initialization
++    derived d2 {{}, {}, 4};      // value-initialized bases
++
++  }
++
++  namespace test_general_range_based_for_loop
++  {
++
++    struct iter
++    {
++      int i;
++
++      int& operator* ()
++      {
++        return i;
++      }
++
++      const int& operator* () const
++      {
++        return i;
++      }
++
++      iter& operator++()
++      {
++        ++i;
++        return *this;
++      }
++    };
++
++    struct sentinel
++    {
++      int i;
++    };
++
++    bool operator== (const iter& i, const sentinel& s)
++    {
++      return i.i == s.i;
++    }
++
++    bool operator!= (const iter& i, const sentinel& s)
++    {
++      return !(i == s);
++    }
++
++    struct range
++    {
++      iter begin() const
++      {
++        return {0};
++      }
++
++      sentinel end() const
++      {
++        return {5};
++      }
++    };
++
++    void f()
++    {
++      range r {};
++
++      for (auto i : r)
++      {
++        [[maybe_unused]] auto v = i;
++      }
++    }
++
++  }
++
++  namespace test_lambda_capture_asterisk_this_by_value
++  {
++
++    struct t
++    {
++      int i;
++      int foo()
++      {
++        return [*this]()
++        {
++          return i;
++        }();
++      }
++    };
++
++  }
++
++  namespace test_enum_class_construction
++  {
++
++    enum class byte : unsigned char
++    {};
++
++    byte foo {42};
++
++  }
++
++  namespace test_constexpr_if
++  {
++
++    template <bool cond>
++    int f ()
++    {
++      if constexpr(cond)
++      {
++        return 13;
++      }
++      else
++      {
++        return 42;
++      }
++    }
++
++  }
++
++  namespace test_selection_statement_with_initializer
++  {
++
++    int f()
++    {
++      return 13;
++    }
++
++    int f2()
++    {
++      if (auto i = f(); i > 0)
++      {
++        return 3;
++      }
++
++      switch (auto i = f(); i + 4)
++      {
++      case 17:
++        return 2;
++
++      default:
++        return 1;
++      }
++    }
++
++  }
++
++  namespace test_template_argument_deduction_for_class_templates
++  {
++
++    template <typename T1, typename T2>
++    struct pair
++    {
++      pair (T1 p1, T2 p2)
++        : m1 {p1},
++          m2 {p2}
++      {}
++
++      T1 m1;
++      T2 m2;
++    };
++
++    void f()
++    {
++      [[maybe_unused]] auto p = pair{13, 42u};
++    }
++
++  }
++
++  namespace test_non_type_auto_template_parameters
++  {
++
++    template <auto n>
++    struct B
++    {};
++
++    B<5> b1;
++    B<'a'> b2;
++
++  }
++
++  namespace test_structured_bindings
++  {
++
++    int arr[2] = { 1, 2 };
++    std::pair<int, int> pr = { 1, 2 };
++
++    auto f1() -> int(&)[2]
++    {
++      return arr;
++    }
++
++    auto f2() -> std::pair<int, int>&
++    {
++      return pr;
++    }
++
++    struct S
++    {
++      int x1 : 2;
++      volatile double y1;
++    };
++
++    S f3()
++    {
++      return {};
++    }
++
++    auto [ x1, y1 ] = f1();
++    auto& [ xr1, yr1 ] = f1();
++    auto [ x2, y2 ] = f2();
++    auto& [ xr2, yr2 ] = f2();
++    const auto [ x3, y3 ] = f3();
++
++  }
++
++  namespace test_exception_spec_type_system
++  {
++
++    struct Good {};
++    struct Bad {};
++
++    void g1() noexcept;
++    void g2();
++
++    template<typename T>
++    Bad
++    f(T*, T*);
++
++    template<typename T1, typename T2>
++    Good
++    f(T1*, T2*);
++
++    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
++
++  }
++
++  namespace test_inline_variables
++  {
++
++    template<class T> void f(T)
++    {}
++
++    template<class T> inline T g(T)
++    {
++      return T{};
++    }
++
++    template<> inline void f<>(int)
++    {}
++
++    template<> int g<>(int)
++    {
++      return 5;
++    }
++
++  }
++
++}  // namespace cxx17
++
++#endif  // __cplusplus < 201703L
++
++]])
diff --git a/app-admin/lnav/lnav-0.9.0-r1.ebuild b/app-admin/lnav/lnav-0.9.0-r1.ebuild
index dbadbc3f2934..3a59325f4267 100644
--- a/app-admin/lnav/lnav-0.9.0-r1.ebuild
+++ b/app-admin/lnav/lnav-0.9.0-r1.ebuild
@@ -35,6 +35,9 @@ PATCHES=(
 	# Fix a segfault when using right arrow
 	# bug 792582
 	"${FILESDIR}"/${PN}-0.9.0-bug792582.patch
+	# Fix a build failure on gcc
+	# bug 786456
+	"${FILESDIR}"/${PN}-0.9.0-bug786456.patch
 )
 
 src_prepare() {