Add Detail::getEnv wrapper that compiles under UWP

Under UWP it will always return nullptr, so UWP will essentially
behave as if the environment was just empty.

src/CMakeLists.txt

@@ -78,6 +78,7 @@ set(INTERNAL_HEADERS
     ${SOURCES_DIR}/internal/catch_exception_translator_registry.hpp
     ${SOURCES_DIR}/internal/catch_fatal_condition_handler.hpp
     ${SOURCES_DIR}/internal/catch_floating_point_helpers.hpp
+    ${SOURCES_DIR}/internal/catch_getenv.hpp
     ${SOURCES_DIR}/internal/catch_istream.hpp
     ${SOURCES_DIR}/internal/catch_unique_name.hpp
     ${SOURCES_DIR}/internal/catch_sharding.hpp
@@ -184,6 +185,7 @@ set(IMPL_SOURCES
     ${SOURCES_DIR}/internal/catch_exception_translator_registry.cpp
     ${SOURCES_DIR}/internal/catch_fatal_condition_handler.cpp
     ${SOURCES_DIR}/internal/catch_floating_point_helpers.cpp
+    ${SOURCES_DIR}/internal/catch_getenv.cpp
     ${SOURCES_DIR}/internal/catch_istream.cpp
     ${SOURCES_DIR}/internal/catch_parse_numbers.cpp
     ${SOURCES_DIR}/interfaces/catch_interfaces_generatortracker.cpp

src/catch2/catch_all.hpp

@@ -68,6 +68,7 @@
 #include <catch2/internal/catch_exception_translator_registry.hpp>
 #include <catch2/internal/catch_fatal_condition_handler.hpp>
 #include <catch2/internal/catch_floating_point_helpers.hpp>
+#include <catch2/internal/catch_getenv.hpp>
 #include <catch2/internal/catch_istream.hpp>
 #include <catch2/internal/catch_lazy_expr.hpp>
 #include <catch2/internal/catch_leak_detector.hpp>

src/catch2/internal/catch_getenv.cpp

@@ -0,0 +1,36 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE_1_0.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+#include <catch2/internal/catch_getenv.hpp>
+#include <catch2/internal/catch_platform.hpp>
+
+#include <cstdlib>
+
+namespace Catch {
+    namespace Detail {
+
+#if defined( CATCH_PLATFORM_WINDOWS_UWP )
+        char const* getEnv( char const* ) { return nullptr; }
+#else
+
+        char const* getEnv( char const* varName ) {
+#    if defined( _MSC_VER )
+#        pragma warning( push )
+#        pragma warning( disable : 4996 ) // use getenv_s instead of getenv
+#    endif
+
+            return std::getenv( varName );
+
+#    if defined( _MSC_VER )
+#        pragma warning( pop )
+#    endif
+#endif
+    }
+
+} // namespace Detail
+} // namespace Catch

src/catch2/internal/catch_getenv.hpp

@@ -0,0 +1,20 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE_1_0.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+#ifndef CATCH_GETENV_HPP_INCLUDED
+#define CATCH_GETENV_HPP_INCLUDED
+
+namespace Catch {
+namespace Detail {
+
+    //! Wrapper over `std::getenv` that compiles on UWP (and always returns nullptr there)
+    char const* getEnv(char const* varName);
+
+}
+}
+
+#endif // CATCH_GETENV_HPP_INCLUDED

src/catch2/meson.build

@@ -90,6 +90,7 @@ internal_headers = [
   'internal/catch_exception_translator_registry.hpp',
   'internal/catch_fatal_condition_handler.hpp',
   'internal/catch_floating_point_helpers.hpp',
+  'internal/catch_getenv.hpp',
   'internal/catch_istream.hpp',
   'internal/catch_lazy_expr.hpp',
   'internal/catch_leak_detector.hpp',
@@ -202,6 +203,7 @@ internal_sources = files(
   'internal/catch_exception_translator_registry.cpp',
   'internal/catch_fatal_condition_handler.cpp',
   'internal/catch_floating_point_helpers.cpp',
+  'internal/catch_getenv.cpp',
   'internal/catch_istream.cpp',
   'internal/catch_lazy_expr.cpp',
   'internal/catch_leak_detector.cpp',