Changed C++20 to emit C++20 instead of C++Latest in MSVC, Added C11 and C17

modules/vstudio/tests/vc2010/test_compile_settings.lua

@@ -1338,6 +1338,21 @@
 		]]
 	end
 
+	function suite.onLanguage_Cpp20_VS2017()
+		p.action.set("vs2017")
+
+		cppdialect 'C++20'
+		prepare()
+		test.capture [[
+<ClCompile>
+	<PrecompiledHeader>NotUsing</PrecompiledHeader>
+	<WarningLevel>Level3</WarningLevel>
+	<Optimization>Disabled</Optimization>
+	<LanguageStandard>stdcpplatest</LanguageStandard>
+</ClCompile>
+		]]
+	end
+
 	function suite.onLanguage_Cpp20_VS2019()
 		p.action.set("vs2019")
 
@@ -1348,7 +1363,37 @@
 	<PrecompiledHeader>NotUsing</PrecompiledHeader>
 	<WarningLevel>Level3</WarningLevel>
 	<Optimization>Disabled</Optimization>
-	<LanguageStandard>stdcpplatest</LanguageStandard>
+	<LanguageStandard>stdcpp20</LanguageStandard>
+</ClCompile>
+		]]
+	end
+
+	function suite.onLanguage_C11_VS2019()
+		p.action.set("vs2019")
+
+		cdialect 'C11'
+		prepare()
+		test.capture [[
+<ClCompile>
+	<PrecompiledHeader>NotUsing</PrecompiledHeader>
+	<WarningLevel>Level3</WarningLevel>
+	<Optimization>Disabled</Optimization>
+	<LanguageStandard_C>stdc11</LanguageStandard_C>
+</ClCompile>
+		]]
+	end
+
+	function suite.onLanguage_C17_VS2019()
+		p.action.set("vs2019")
+
+		cdialect 'C17'
+		prepare()
+		test.capture [[
+<ClCompile>
+	<PrecompiledHeader>NotUsing</PrecompiledHeader>
+	<WarningLevel>Level3</WarningLevel>
+	<Optimization>Disabled</Optimization>
+	<LanguageStandard_C>stdc17</LanguageStandard_C>
 </ClCompile>
 		]]
 	end

modules/vstudio/vs2010_vcxproj.lua

@@ -389,6 +389,7 @@
 			m.compileAs,
 			m.callingConvention,
 			m.languageStandard,
+			m.languageStandardC,
 			m.conformanceMode,
 			m.structMemberAlignment,
 			m.useFullPaths,
@@ -1477,13 +1478,25 @@
 			elseif (cfg.cppdialect == "C++17") then
 				m.element("LanguageStandard", nil, 'stdcpp17')
 			elseif (cfg.cppdialect == "C++20") then
-				m.element("LanguageStandard", nil, 'stdcpplatest')
+				m.element("LanguageStandard", nil, iif(_ACTION == "vs2017", 'stdcpplatest', 'stdcpp20'))
 			elseif (cfg.cppdialect == "C++latest") then
 				m.element("LanguageStandard", nil, 'stdcpplatest')
 			end
 		end
 	end
 
+
+	function m.languageStandardC(cfg)
+		if _ACTION >= "vs2019" then
+			if (cfg.cdialect == "C11") then
+				m.element("LanguageStandard_C", nil, 'stdc11')
+			elseif (cfg.cdialect == "C17") then
+				m.element("LanguageStandard_C", nil, 'stdc17')
+			end
+		end
+	end
+
+
 	function m.conformanceMode(cfg)
 		if _ACTION >= "vs2017" then
 			if cfg.conformancemode ~= nil then

src/_premake_init.lua

@@ -757,6 +757,7 @@
 			"C90",
 			"C99",
 			"C11",
+			"C17",
 			"gnu89",
 			"gnu90",
 			"gnu99",

website/docs/cdialect.md

@@ -13,6 +13,7 @@ cdialect "value"
 * `C90`: ISO C90
 * `C99`: ISO C99
 * `C11`: ISO C11
+* `C17`: ISO C17
 * `gnu89`: GNU dialect of ISO C89
 * `gnu90`: GNU dialect of ISO C90
 * `gnu99`: GNU dialect of ISO C99