Check C++17 support (#2)

Signed-off-by: Uilian Ries <uilianries@gmail.com>

recipes/libsigcpp/3.0.0/conanfile.py

@@ -1,5 +1,8 @@
 import os
 from conans import ConanFile, CMake, tools
+from conans.errors import ConanInvalidConfiguration
+from conans.tools import Version
+
 
 class LibSigCppConan(ConanFile):
     name = "libsigcpp"
@@ -23,6 +26,26 @@ def _source_subfolder(self):
     def _build_subfolder(self):
         return "build_subfolder"
 
+    @property
+    def _supported_cppstd(self):
+        return ["17", "gnu17", "20", "gnu20"]
+
+    def configure(self):
+        compiler_version = Version(self.settings.compiler.version)
+        if self.settings.compiler.cppstd and \
+           not self.settings.compiler.cppstd in self._supported_cppstd:
+          raise ConanInvalidConfiguration("This library requires c++17 standard or higher."
+                                          " {} required."
+                                          .format(self.settings.compiler.cppstd))
+        if (self.settings.compiler == "gcc" and compiler_version < "7") or \
+           (self.settings.compiler == "Visual Studio" and compiler_version < "15") or \
+           (self.settings.compiler == "clang" and compiler_version < "5") or \
+           (self.settings.compiler == "apple-clang" and compiler_version < "9"):
+          raise ConanInvalidConfiguration("This library requires C++17 or higher support standard."
+                                          " {} {} is not supported."
+                                          .format(self.settings.compiler,
+                                                  self.settings.compiler.version))
+
     def source(self):
         tools.get(**self.conan_data["sources"][self.version])
         extracted_dir = "libsigc++-" + self.version