Add UnsignedChar API + implement for gcc

src/_premake_init.lua

@@ -1336,6 +1336,12 @@
 		}
 	}
 
+	api.register {
+		name = "unsignedchar",
+		scope = "config",
+		kind = "boolean",
+	}
+
 -----------------------------------------------------------------------------
 --
 -- Field name aliases for backward compatibility

src/tools/gcc.lua

@@ -96,6 +96,10 @@
 		},
 		symbols = {
 			On = "-g"
+		},
+		unsignedchar = {
+			On = "-funsigned-char",
+			Off = "-fno-unsigned-char"
 		}
 	}
 

tests/tools/test_gcc.lua

@@ -788,3 +788,23 @@
 		test.contains({ "-std=gnu++17" }, gcc.getcxxflags(cfg))
 		test.contains({ }, gcc.getcflags(cfg))
 	end
+
+--
+-- Test unsigned-char flags.
+--
+
+	function suite.sharedflags_onUnsignedChar()
+		unsignedchar "On"
+
+		prepare()
+		test.contains({ "-funsigned-char" }, gcc.getcxxflags(cfg))
+		test.contains({ "-funsigned-char" }, gcc.getcflags(cfg))
+	end
+
+	function suite.sharedflags_onNoUnsignedChar()
+		unsignedchar "Off"
+
+		prepare()
+		test.contains({ "-fno-unsigned-char" }, gcc.getcxxflags(cfg))
+		test.contains({ "-fno-unsigned-char" }, gcc.getcflags(cfg))
+	end