ICU-21107 Update ICU4C minimum standard version from C++11 to C++17

.github/workflows/icu4c.yml

@@ -130,17 +130,17 @@ jobs:
           make check;
 
   # Out of source build with gcc 10, c++14, and extra warnings; executes icuinfo.
-  gcc-10-stdlib14:
+  gcc-10-stdlib17:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
 
-      - name: ICU4C with gcc 10 and c++14 and extra warnings.
+      - name: ICU4C with gcc 10 and c++17 and extra warnings.
         env:
           PREFIX: /tmp/icu-prefix
           CC: gcc-10
           CXX: g++-10
-          CXXFLAGS: -std=c++14 -Wextra
+          CXXFLAGS: -std=c++17 -Wextra
         run: |
           mkdir build;
           cd build;

docs/userguide/icu4c/build.md

@@ -200,7 +200,7 @@ The value of `v140` corresponds to the Visual Studio 2015 compiler tool set, whe
 
 In order to build the non-UWP projects with Visual Studio 2015 you will need to modify the file called `Build.Windows.ProjectConfiguration.props` to change the value of the `PlatformToolset` property. Note however that Visual Studio 2017 is required for building the UWP projects.
 
-> :point_right: **Note**: Using older versions of the MSVC compiler is generally not recommended due to the improved support for the C++11 standard in newer versions of the compiler.
+> :point_right: **Note**: Using older versions of the MSVC compiler is generally not recommended due to the improved support for the C++17 standard in newer versions of the compiler.
 
 ### Re-targeting the Windows 10 SDK for the UWP projects
 

icu4c/build_qnx/build-hooks

@@ -15,7 +15,7 @@ function hook_preconfigure {
 
 		CFLAGS="$CFLAGS -fPIC"
 		CPPFLAGS="$CPPFLAGS -fPIC"
-		CXXFLAGS="$CXXFLAGS -std=gnu++11"
+		CXXFLAGS="$CXXFLAGS -std=gnu++17"
 	else
 # prefix is the base path where architecture independent files are installed in the target filesystem
 		configure_opts="${configure_opts} --prefix=/"

icu4c/source/Doxyfile.in

@@ -2084,7 +2084,7 @@ PREDEFINED             = U_EXPORT2= \
                          U_DEFINE_LOCAL_OPEN_POINTER()= \
                          U_IN_DOXYGEN=1 \
                          U_CHAR16_IS_TYPEDEF=0 \
-                         U_CPLUSPLUS_VERSION=11 \
+                         U_CPLUSPLUS_VERSION=17 \
                          U_WCHAR_IS_UTF16
 
 # If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then this

icu4c/source/common/unicode/platform.h

@@ -507,6 +507,8 @@
     /* Otherwise use the predefined value. */
 #elif !defined(__cplusplus)
 #   define U_CPLUSPLUS_VERSION 0
+#elif __cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
+#   define U_CPLUSPLUS_VERSION 17
 #elif __cplusplus >= 201402L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201402L)
 #   define U_CPLUSPLUS_VERSION 14
 #elif __cplusplus >= 201103L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201103L)

icu4c/source/config/mh-solaris

@@ -5,8 +5,8 @@
 ## Copyright (c) 1999-2010, International Business Machines Corporation and
 ## others. All Rights Reserved.
 
-## Flags for ICU 59+
-CXXFLAGS += -std=c++11
+## Flags for ICU 75+
+CXXFLAGS += -std=c++17
 CFLAGS   += -std=c11
 
 ## Flags for position independent code

icu4c/source/configure

@@ -3515,8 +3515,8 @@ ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
 ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
-# Make sure that we try clang++ first, which provides C++11 support.
-# The g++ compiler is less likely to support C++11.
+# Make sure that we try clang++ first, which provides C++17 support.
+# The g++ compiler is less likely to support C++17.
 ac_ext=cpp
 ac_cpp='$CXXCPP $CPPFLAGS'
 ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -6128,13 +6128,13 @@ $as_echo "no" >&6; }
 fi
 
 if [ "$GXX" = yes ]; then
-    # if CXXFLAGS does not have a "-std=" setting, set it now to -std=c++11,
+    # if CXXFLAGS does not have a "-std=" setting, set it now to -std=c++17,
     # and check that the compiler still works.
     if ! echo "$CXXFLAGS" | grep '\-std=' >/dev/null 2>&1; then
         OLD_CXXFLAGS="${CXXFLAGS}"
-        CXXFLAGS="$CXXFLAGS -std=c++11"
-        { $as_echo "$as_me:${as_lineno-$LINENO}: checking if we have a C++11 compiler" >&5
-$as_echo_n "checking if we have a C++11 compiler... " >&6; }
+        CXXFLAGS="$CXXFLAGS -std=c++17"
+        { $as_echo "$as_me:${as_lineno-$LINENO}: checking if we have a C++17 compiler" >&5
+$as_echo_n "checking if we have a C++17 compiler... " >&6; }
         cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -6147,17 +6147,17 @@ main ()
 }
 _ACEOF
 if ac_fn_cxx_try_compile "$LINENO"; then :
-  cxx11_okay=yes
+  cxx17_okay=yes
 else
-  cxx11_okay=no
+  cxx17_okay=no
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-        { $as_echo "$as_me:${as_lineno-$LINENO}: result: $cxx11_okay" >&5
-$as_echo "$cxx11_okay" >&6; }
-        if [ $cxx11_okay = yes ]; then
-            { $as_echo "$as_me:${as_lineno-$LINENO}: Adding CXXFLAGS option -std=c++11" >&5
-$as_echo "$as_me: Adding CXXFLAGS option -std=c++11" >&6;}
-            UCONFIG_CXXFLAGS="${UCONFIG_CXXFLAGS} -std=c++11"
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: $cxx17_okay" >&5
+$as_echo "$cxx17_okay" >&6; }
+        if [ $cxx17_okay = yes ]; then
+            { $as_echo "$as_me:${as_lineno-$LINENO}: Adding CXXFLAGS option -std=c++17" >&5
+$as_echo "$as_me: Adding CXXFLAGS option -std=c++17" >&6;}
+            UCONFIG_CXXFLAGS="${UCONFIG_CXXFLAGS} -std=c++17"
         else
             CXXFLAGS="$OLD_CXXFLAGS"
         fi

icu4c/source/configure.ac

@@ -148,8 +148,8 @@ AC_SUBST(ENABLE_RELEASE)
 
 # Checks for compilers
 AC_PROG_CC([clang gcc cc c99 c89 xlc_r xlc cl.exe icc])
-# Make sure that we try clang++ first, which provides C++11 support.
-# The g++ compiler is less likely to support C++11.
+# Make sure that we try clang++ first, which provides C++17 support.
+# The g++ compiler is less likely to support C++17.
 AC_PROG_CXX([clang++ g++ c++ gpp xlC_r xlC aCC CC cxx cc++ cl.exe icc FCC KCC RCC])
 
 # pkg-config is needed for harfbuzz support
@@ -513,17 +513,17 @@ else
 fi
 
 if [[ "$GXX" = yes ]]; then
-    # if CXXFLAGS does not have a "-std=" setting, set it now to -std=c++11,
+    # if CXXFLAGS does not have a "-std=" setting, set it now to -std=c++17,
     # and check that the compiler still works.
     if ! echo "$CXXFLAGS" | grep '\-std=' >/dev/null 2>&1; then
         OLD_CXXFLAGS="${CXXFLAGS}"
-        CXXFLAGS="$CXXFLAGS -std=c++11"
-        AC_MSG_CHECKING([[if we have a C++11 compiler]])
-        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]],[[]])],[cxx11_okay=yes],[cxx11_okay=no])
-        AC_MSG_RESULT($cxx11_okay)
-        if [[ $cxx11_okay = yes ]]; then
-            AC_MSG_NOTICE([Adding CXXFLAGS option -std=c++11])
-            UCONFIG_CXXFLAGS="${UCONFIG_CXXFLAGS} -std=c++11"
+        CXXFLAGS="$CXXFLAGS -std=c++17"
+        AC_MSG_CHECKING([[if we have a C++17 compiler]])
+        AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]],[[]])],[cxx17_okay=yes],[cxx17_okay=no])
+        AC_MSG_RESULT($cxx17_okay)
+        if [[ $cxx17_okay = yes ]]; then
+            AC_MSG_NOTICE([Adding CXXFLAGS option -std=c++17])
+            UCONFIG_CXXFLAGS="${UCONFIG_CXXFLAGS} -std=c++17"
         else
             CXXFLAGS="$OLD_CXXFLAGS"
         fi

icu4c/source/test/depstest/dependencies.txt

@@ -125,6 +125,7 @@ group: cplusplus
     # even when no code actually uses it.
     # ICU must not _use_ the global operator delete.
     "operator delete(void*)"
+    "operator delete(void*, unsigned long)"
     # ICU also must not use the global operator new.
     # "operator new[](unsigned long)"
 

icu4c/source/test/hdrtst/testinternalheaders.sh

@@ -17,7 +17,7 @@ for file in `ls common/*.h`; do
     echo $file
     echo '#include "'$file'"' > ht_temp.cpp ;
     echo 'void noop() {}' >> ht_temp.cpp ;
-    $CXX -c -std=c++11 -I common -DU_COMMON_IMPLEMENTATION -O0 ht_temp.cpp ;
+    $CXX -c -std=c++17 -I common -DU_COMMON_IMPLEMENTATION -O0 ht_temp.cpp ;
     if [ $? != 0 ] ; then
         ERROR_EXIT=1
     fi
@@ -27,7 +27,7 @@ for file in `ls i18n/*.h`; do
     echo $file
     echo '#include "'$file'"' > ht_temp.cpp ;
     echo 'void noop() {}' >> ht_temp.cpp ;
-    $CXX -c -std=c++11 -I common -I i18n -DU_I18N_IMPLEMENTATION -O0 ht_temp.cpp ;
+    $CXX -c -std=c++17 -I common -I i18n -DU_I18N_IMPLEMENTATION -O0 ht_temp.cpp ;
     if [ $? != 0 ] ; then
         ERROR_EXIT=1
     fi
@@ -37,7 +37,7 @@ for file in `ls io/*.h`; do
     echo $file
     echo '#include "'$file'"' > ht_temp.cpp ;
     echo 'void noop() {}' >> ht_temp.cpp ;
-    $CXX -c -std=c++11 -I common -I i18n -I io -DU_IO_IMPLEMENTATION -O0 ht_temp.cpp ;
+    $CXX -c -std=c++17 -I common -I i18n -I io -DU_IO_IMPLEMENTATION -O0 ht_temp.cpp ;
     if [ $? != 0 ] ; then
         ERROR_EXIT=1
     fi
@@ -61,7 +61,7 @@ for file in `ls tools/toolutil/*.h`; do
     echo $file
     echo '#include "'$file'"' > ht_temp.cpp ;
     echo 'void noop() {}' >> ht_temp.cpp ;
-    $CXX -c -std=c++11 -I common -I i18n -I io -I tools/toolutil -O0 ht_temp.cpp ;
+    $CXX -c -std=c++17 -I common -I i18n -I io -I tools/toolutil -O0 ht_temp.cpp ;
     if [ $? != 0 ] ; then
         ERROR_EXIT=1
     fi
@@ -78,7 +78,7 @@ for tool in escapesrc genccode gencmn gencolusb gennorm2 genren gentest icupkg i
         echo $file
         echo '#include "'$file'"' > ht_temp.cpp ;
         echo 'void noop() {}' >> ht_temp.cpp ;
-        $CXX -c -std=c++11 -I common -I i18n -I io -I tools/toolutil -I tools/$tool -O0 ht_temp.cpp ;
+        $CXX -c -std=c++17 -I common -I i18n -I io -I tools/toolutil -I tools/$tool -O0 ht_temp.cpp ;
         if [ $? != 0 ] ; then
             ERROR_EXIT=1
         fi
@@ -91,7 +91,7 @@ for file in `ls tools/ctestfw/unicode/*.h`; do
     echo $file
     echo '#include "'$file'"' > ht_temp.cpp ;
     echo 'void noop() {}' >> ht_temp.cpp ;
-    $CXX -c -std=c++11 -I common -I i18n -I io -I tools/toolutil -I tools/ctestfw -O0 ht_temp.cpp ;
+    $CXX -c -std=c++17 -I common -I i18n -I io -I tools/toolutil -I tools/ctestfw -O0 ht_temp.cpp ;
     if [ $? != 0 ] ; then
         ERROR_EXIT=1
     fi
@@ -113,7 +113,7 @@ for test in intltest iotest testmap thaitest fuzzer; do
         echo $file
         echo '#include "'$file'"' > ht_temp.cpp ;
         echo 'void noop() {}' >> ht_temp.cpp ;
-        $CXX -c -std=c++11 -I common -I i18n -I io -I tools/toolutil -I tools/ctestfw -I test/$test -O0 ht_temp.cpp ;
+        $CXX -c -std=c++17 -I common -I i18n -I io -I tools/toolutil -I tools/ctestfw -I test/$test -O0 ht_temp.cpp ;
         if [ $? != 0 ] ; then
             ERROR_EXIT=1
         fi

tools/unicode/c/CMakeLists.txt

@@ -7,7 +7,7 @@
 # created by: Markus W. Scherer
 cmake_minimum_required(VERSION 2.6)
 project(ICU_UNI_TOOLS)
-set(CMAKE_CXX_FLAGS "-std=c++11 -fsanitize=bounds")
+set(CMAKE_CXX_FLAGS "-std=c++17 -fsanitize=bounds")
 set(CMAKE_LD_FLAGS "-fsanitize=bounds")
 # This requires an icudefs.txt file with contents like the following:
 # Location (--prefix) of where ICU was installed.

tools/unicode/c/genregexcasing/Makefile

@@ -13,4 +13,4 @@ data: genregexcasing
 	LD_LIBRARY_PATH=$(ICU_BUILD)/lib:$(ICU_BUILD)/stubdata ICU_DATA=$(ICU_BUILD)/data/out ./genregexcasing
 
 genregexcasing: genregexcasing.cpp
-	clang++ genregexcasing.cpp -std=c++0x -g -I $(ICU_HOME)/common -I $(ICU_HOME)/i18n -I $(ICU_HOME)/io -L$(ICU_BUILD)/lib -L$(ICU_BUILD)/stubdata -licuuc -licui18n -licudata -o genregexcasing 
+	clang++ genregexcasing.cpp -std=c++17 -g -I $(ICU_HOME)/common -I $(ICU_HOME)/i18n -I $(ICU_HOME)/io -L$(ICU_BUILD)/lib -L$(ICU_BUILD)/stubdata -licuuc -licui18n -licudata -o genregexcasing