SLmetrics/configure.win at development · serkor1/SLmetrics · GitHub

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#!/usr/bin/env sh

## Description:
##
## Script used to generate Makevars.win from Makevars.win.in on Windows
## It checks for available C++ standards in descending order:
##    C++23, then C++20, then C++17.
## If none is available, installation is aborted.

## 0) Create a small program
##    to test for CXXSTD and
##    store as environment
##    variable
cat > test_cpp_version.cpp << 'EOF'
#include <iostream>
int main() {
    std::cout << __cplusplus;
    return 0;
}
EOF

test_cpp_standard() {
    std_flag="$1"
    ${CXX} $std_flag -o test_cpp_version test_cpp_version.cpp 2>/dev/null
    if test $? -eq 0; then
        result=`./test_cpp_version`
        echo $result
        return 0
    else
        return 1
    fi
}

## 1) Locate R Home
##    this is where R is stored
##    often a standard location. And compile
##    program with standard compiler built
##    shipped with R
##
##    NOTE: It may, or may not, be a a good idea
##    to search for it in alternative locations
##    for users using containers, dockers and other
##    stuff that changes essential stuff
R_EXE="${R_HOME}/bin${R_ARCH_BIN}/R"
CXX=`"${R_EXE}" CMD config CXX`
CPP_SUPPORTED="no"

## 2) List all possible
##    CXXSTD
STD_C23=`"${R_EXE}" CMD config CXX23STD`
STD_C20=`"${R_EXE}" CMD config CXX20STD`
STD_C17=`"${R_EXE}" CMD config CXX17STD`

## 3) Check for C++23
##    if not available try C++20, and
##    fall back on C++17 (if not available it will abort)
## 3.1) C++23
if test -n "$STD_C23"; then
    value=`test_cpp_standard "$STD_C23"`
    if test $? -eq 0 && test "$value" -ge 202302; then
         CXXFLAGS=`"${R_EXE}" CMD config CXX23FLAGS`
         CXX_STD="CXX23"
         CPP_SUPPORTED="yes"
    fi
fi

## 3.2) C++20
if test "$CPP_SUPPORTED" = "no" && test -n "$STD_C20"; then
    value=`test_cpp_standard "$STD_C20"`
    if test $? -eq 0 && test "$value" -ge 202002; then
         CXXFLAGS=`"${R_EXE}" CMD config CXX20FLAGS`
         CXX_STD="CXX20"
         CPP_SUPPORTED="yes"
    fi
fi

## 3.3) C++17
if test "$CPP_SUPPORTED" = "no" && test -n "$STD_C17"; then
    value=`test_cpp_standard "$STD_C17"`
    if test $? -eq 0 && test "$value" -ge 201703; then
         CXXFLAGS=`"${R_EXE}" CMD config CXX17FLAGS`
         CXX_STD="CXX17"
         CPP_SUPPORTED="yes"
    fi
fi

## 3.4) Abort installation if no
##      CXXSTD17 compiler is available.
##      or echo the CXXSTD
if test "$CPP_SUPPORTED" = "no"; then
    echo "ERROR: Your C++ compiler does not support C++17 or later."
    rm -f test_cpp_version.cpp test_cpp_version
    exit 1
fi

echo "Using C++ standard: $CXX_STD"

## 4) Extract additional
##    flags
CPPFLAGS=`"${R_EXE}" CMD config CPPFLAGS`

## 5) Create Makevars.win
sed -e "s/@CXX_STD@/$CXX_STD/" < src/Makevars.win.in > src/Makevars.win

exit 0