Fixed issues with unsigned to signed conversion.

Added format.h to VS2022 project.
Added format.h to syntax check CMakeLists.txt

include/etl/format.h

@@ -914,17 +914,17 @@ namespace etl
     {
       if (value <= 9)
       {
-        *it = '0' + value;
+        *it = static_cast<char_type>('0' + static_cast<typename etl::make_unsigned<T>::type>(value));
       }
       else
       {
         if (spec.type.has_value() && is_uppercase(spec.type.value()))
         {
-          *it = 'A' + (value - 10);
+          *it = static_cast<char_type>('A' + static_cast<typename etl::make_unsigned<T>::type>(value - 10));
         }
         else
         {
-          *it = 'a' + (value - 10);
+          *it = static_cast<char_type>('a' + static_cast<typename etl::make_unsigned<T>::type>(value - 10));
         }
       }
       ++it;
@@ -955,7 +955,7 @@ namespace etl
     {
       using UnsignedT = typename etl::make_unsigned<T>::type;
 
-      UnsignedT unsigned_value = static_cast<UnsignedT>(value < 0 ? -value : value);
+      UnsignedT unsigned_value = etl::absolute_unsigned(value);
 
       size_t base = base_from_spec<default_base>(spec);
       UnsignedT highest_digit = get_highest_digit<UnsignedT>(unsigned_value, base);
@@ -2195,10 +2195,7 @@ namespace etl
       {
         private_format::output<OutputIt>(fmt_context, c);
       }
-    };
+    }
-
-    // plain strings need it, back insert iterators don't:
-    //*fmt_context.out() = '\0';
 
     return fmt_context.out();
   }

test/syntax_check/CMakeLists.txt

@@ -198,6 +198,7 @@ target_sources(tests PRIVATE
 		flat_multiset.h.t.cpp
 		flat_set.h.t.cpp
 		fnv_1.h.t.cpp
+		format.h.t.cpp
 		format_spec.h.t.cpp
 		forward_list.h.t.cpp
 		frame_check_sequence.h.t.cpp

test/syntax_check/format.h.t.cpp

@@ -0,0 +1,29 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2025 John Wellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+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 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
+SOFTWARE.
+******************************************************************************/
+
+#include <etl/format.h>

test/test_format.cpp

@@ -80,8 +80,8 @@ namespace
       CHECK_EQUAL("1 2", test_format(s, "{} {}", 1, 2));
       CHECK_EQUAL("-123", test_format(s, "{}", -123));
       CHECK_EQUAL("-314748364", test_format(s, "{}", (int)-314748364));
-      CHECK_EQUAL("2147483647", test_format(s, "{}", (int)2147483647));
+      CHECK_EQUAL("2147483647", test_format(s, "{}", INT32_MAX));
-      CHECK_EQUAL("-2147483648", test_format(s, "{}", (int)-2147483648));
+      CHECK_EQUAL("-2147483648", test_format(s, "{}", INT32_MIN));
       CHECK_EQUAL("0", test_format(s, "{}", 0));
       CHECK_EQUAL("-1", test_format(s, "{}", -1));
     }

test/vs2022/etl.vcxproj

@@ -3465,6 +3465,7 @@
     <ClInclude Include="..\..\include\etl\buffer_descriptors.h" />
     <ClInclude Include="..\..\include\etl\byte.h" />
     <ClInclude Include="..\..\include\etl\byte_stream.h" />
+    <ClInclude Include="..\..\include\etl\callback.h" />
     <ClInclude Include="..\..\include\etl\callback_timer.h" />
     <ClInclude Include="..\..\include\etl\callback_timer_atomic.h" />
     <ClInclude Include="..\..\include\etl\callback_timer_deferred_locked.h" />
@@ -6750,6 +6751,26 @@
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++20 - Force C++03|Win32'">true</ExcludedFromBuild>
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++20 - Force C++03 - No virtual messages|Win32'">true</ExcludedFromBuild>
     </ClCompile>
+    <ClCompile Include="..\syntax_check\format.h.t.cpp">
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++20|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++20 - No virtual imessage|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++ 20 - No Tests|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++23 - No STL|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++23|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++20 - No STL|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++14|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release MSVC C++20 - No STL - Optimised -O2|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release MSVC C++20 - No STL - Optimised -O2 - Sanitiser|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++20 - Force C++03 - No virtual messages|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++17|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++17 - No STL|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release MSVC C++20 - Optimised O2|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++20 - No virtual messages|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++14 - No STL|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++20 - Force C++03|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug Clang C++20|Win32'">true</ExcludedFromBuild>
+      <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug Clang C++20 - Optimised -O2|Win32'">true</ExcludedFromBuild>
+    </ClCompile>
     <ClCompile Include="..\syntax_check\format_spec.h.t.cpp">
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug MSVC C++20|Win32'">true</ExcludedFromBuild>
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Debug Clang C++20|Win32'">true</ExcludedFromBuild>
@@ -10298,6 +10319,7 @@
     <ClCompile Include="..\test_delegate_observable.cpp" />
     <ClCompile Include="..\test_etl_assert.cpp" />
     <ClCompile Include="..\test_expected.cpp" />
+    <ClCompile Include="..\test_format.cpp" />
     <ClCompile Include="..\test_function_traits.cpp" />
     <ClCompile Include="..\test_hfsm_recurse_to_inner_state_on_start.cpp" />
     <ClCompile Include="..\test_hfsm_transition_on_enter.cpp" />

test/vs2022/etl.vcxproj.filters

@@ -1527,6 +1527,9 @@
     <ClInclude Include="..\..\include\etl\crc64_iso.h">
       <Filter>ETL\Maths\CRC</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\include\etl\callback.h">
+      <Filter>ETL\Utilities</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\test_string_char.cpp">
@@ -3737,6 +3740,12 @@
     <ClCompile Include="..\test_signal.cpp">
       <Filter>Tests\Callbacks &amp; Delegates</Filter>
     </ClCompile>
+    <ClCompile Include="..\syntax_check\format.h.t.cpp">
+      <Filter>Tests\Syntax Checks\Source</Filter>
+    </ClCompile>
+    <ClCompile Include="..\test_format.cpp">
+      <Filter>Tests\Strings</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <None Include="..\..\library.properties">