Guards around usage of std::initializer_list in optional.h (#1186)

* Guards around usage of std::initializer_list in optional.h

In optional.h, ETL_HAS_INITIALIZER_LIST is being used to
guard against cases where std::initializer_list is not available.
But not consistently. This changes fixes it by adding it in the
remaining places.

* Fixed #undef in optional.h

Instead of undefining ETL_OPTIONAL_ENABLE_CONSTEXPR_BOOL_RETURN_CPP14,
ETL_OPTIONAL_ENABLE_CONSTEXPR_BOOL_RETURN_CPP20_STL was undefined twice
(one of the misspelled).

* Fix comment typos

Author: rolandreichweinbmw

include/etl/gcd.h

@@ -21,7 +21,7 @@ copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR Value1 PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

include/etl/lcm.h

@@ -21,7 +21,7 @@ copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR Value1 PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

include/etl/optional.h

@@ -195,6 +195,7 @@ namespace etl
         storage.construct(etl::forward<TArgs>(args)...);
       }
 
+#if ETL_HAS_INITIALIZER_LIST
       //*******************************************
       /// Construct from initializer_list and arguments.
       //*******************************************
@@ -205,6 +206,7 @@ namespace etl
       {
         storage.construct(ilist, etl::forward<TArgs>(args)...);
       }
+#endif
 #endif
 
       //***************************************************************************
@@ -816,6 +818,7 @@ namespace etl
         storage.construct(etl::forward<TArgs>(args)...);
       }
 
+#if ETL_HAS_INITIALIZER_LIST
       //*******************************************
       /// Construct from initializer_list and arguments.
       //*******************************************
@@ -826,6 +829,7 @@ namespace etl
       {
         storage.construct(ilist, etl::forward<TArgs>(args)...);
       }
+#endif
 #endif
 
       //***************************************************************************
@@ -2313,7 +2317,7 @@ ETL_CONSTEXPR20_STL void swap(etl::optional<T>& lhs, etl::optional<T>& rhs)
 #undef ETL_OPTIONAL_ENABLE_CPP14
 #undef ETL_OPTIONAL_ENABLE_CPP20_STL
 
+#undef ETL_OPTIONAL_ENABLE_CONSTEXPR_BOOL_RETURN_CPP14
 #undef ETL_OPTIONAL_ENABLE_CONSTEXPR_BOOL_RETURN_CPP20_STL
-#undef ETL_OPTIONAL_ENABLE_COMSTEXPR_BOOL_RETURN_CPP20_STL
 
 #endif

include/etl/private/chrono/duration.h

@@ -21,7 +21,7 @@ copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR Value1 PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

include/etl/ratio.h

@@ -21,7 +21,7 @@ copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR Value1 PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE