Require C++14 or newer (#4784) (#4786)

configure.ac

@@ -354,7 +354,7 @@ AC_SUBST(CFG_CXXFLAGS_PROFILE)
 # Macros work such that first option that passes is the one we take
 # Currently enable c++17/c++14 due to packaged SystemC dependency
 # c++17 is the newest that Verilator is regularly tested to support
-# c++11 is the oldest that Verilator supports
+# c++14 is the oldest that Verilator supports
 # gnu is required for Cygwin to compile verilated.h successfully
 #_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=gnu++20)
 #_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=c++20)
@@ -362,8 +362,6 @@ _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=gnu++17)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=c++17)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=gnu++14)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=c++14)
-_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=gnu++11)
-_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=c++11)
 AC_SUBST(CFG_CXXFLAGS_STD_NEWEST)
 
 # Flags for compiling Verilator internals including parser, and Verilated files
@@ -521,14 +519,14 @@ _MY_LDLIBS_CHECK_IFELSE(
    fi])
 AC_SUBST(CFG_LIBS)
 
-# Need C++11 at least
-#Alternative: AX_CXX_COMPILE_STDCXX([11])
+# Need C++14 at least
+#Alternative: AX_CXX_COMPILE_STDCXX([14])
 AC_DEFUN([_MY_CXX_CHECK_CXX_VER],
-   [# _MY_CXX_CHECK_CXX_VER(flag) -- Check if compiler runs C++11
+   [# _MY_CXX_CHECK_CXX_VER(flag) -- Check if compiler runs C++14
     # Set $_my_result
     AC_LINK_IFELSE(
      [AC_LANG_PROGRAM([#include <thread>
-#if (__cplusplus < 201103L)
+#if (__cplusplus < 201402L)
 # error "Too old"
 #endif
     ], [[ ]])],
@@ -544,13 +542,13 @@ AC_DEFUN([_MY_CXX_CHECK_CXX_VER],
 # Add $CFG_CXXFLAGS_STD only if can't compile correctly otherwise,
 # as adding std= when not needed can cause errors with the C++ std library.
 CFG_CXXFLAGS_STD=$CFG_CXXFLAGS_STD_NEWEST
-AC_MSG_CHECKING(whether $CXX supports C++11)
+AC_MSG_CHECKING(whether $CXX supports C++14)
 _MY_CXX_CHECK_CXX_VER()
 AC_MSG_RESULT($_my_result)
 if test "$_my_result" = "no" ; then
    CXXFLAGS="$CXXFLAGS $CFG_CXXFLAGS_STD"
    CFG_CXX_FLAGS_CMAKE="$CFG_CXX_FLAGS_CMAKE $CFG_CXXFLAGS_STD"
-   AC_MSG_CHECKING(whether $CXX supports C++11 with $CFG_CXXFLAGS_STD)
+   AC_MSG_CHECKING(whether $CXX supports C++14 with $CFG_CXXFLAGS_STD)
    _MY_CXX_CHECK_CXX_VER()
    AC_MSG_RESULT($_my_result)
 else
@@ -560,9 +558,9 @@ else
 fi
 if test "$_my_result" = "no" ; then
    AC_MSG_NOTICE([[]])
-   AC_MSG_ERROR([[the $CXX compiler appears to not support C++11.
+   AC_MSG_ERROR([[the $CXX compiler appears to not support C++14.
 
-Verilator requires a C++11 or newer compiler.]])
+Verilator requires a C++14 or newer compiler.]])
 
 fi
 AC_SUBST(CFG_CXXFLAGS_STD)

docs/CONTRIBUTORS

@@ -144,6 +144,7 @@ Piotr Binkowski
 Qingyao Sun
 Quentin Corradi
 Rafal Kapuscik
+Rasfunk
 Raynard Qiao
 Richard Myers
 Risto Pejašinović

docs/guide/deprecations.rst

@@ -8,11 +8,8 @@ The following deprecated items are scheduled for future removal:
 
 C++11 compiler support
   Verilator currently requires a C++20 or newer compiler for timing, and a
-  C++11 or newer compiler for no-timing.
-
-  Verilator will require C++14 or newer compilers for both compiling
-  Verilator and compiling Verilated models with --no-timing no sooner than
-  January 2023.
+  C++14 or newer compiler for both compiling Verilator and compiling
+  Verilated models with --no-timing.
 
   Verilator will require C++20 or newer compilers for both compiling
   Verilator and compiling all Verilated models no sooner than January 2025.

docs/internals.rst

@@ -1035,11 +1035,11 @@ Coding Conventions
 ==================
 
 
-Compiler Version and C++11
+Compiler Version and C++14
 --------------------------
 
-Verilator requires C11. Verilator does not require any newer versions, but
-is maintained to build successfully with C14/C17/C20.
+Verilator requires C14. Verilator does not require any newer versions, but
+is maintained to build successfully with C17/C20.
 
 
 Indentation and Naming Style

include/verilatedos.h

@@ -258,11 +258,11 @@
 #endif
 
 //=========================================================================
-// C++-2011
+// C++-2014
 
-#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__) || defined(VL_CPPCHECK) || defined(_MSC_VER)
+#if __cplusplus >= 201402L || defined(__GXX_EXPERIMENTAL_CXX0X__) || defined(VL_CPPCHECK) || defined(_MSC_VER)
 #else
-# error "Verilator requires a C++11 or newer compiler"
+# error "Verilator requires a C++14 or newer compiler"
 #endif
 
 #ifndef VL_NO_LEGACY