Support absolute paths in scripts, to reference a different Windows drive letter.

samples/project/CppConsoleApp/premake4.lua

@@ -5,5 +5,7 @@ project "CppConsoleApp"
 	
 	files    "*.cpp"
 	
+	includedirs { "I:/Code" }
+	
 	libdirs { "../lib" }
 	links   { "CppSharedLib" }

src/base/path.lua

@@ -67,6 +67,20 @@
 	end
 
 
+--
+-- Retrieve the drive letter, if a Windows path.
+--
+
+	function path.getdrive(p)
+		local ch1 = p:sub(1,1)
+		local ch2 = p:sub(2,2)
+		if ch2 == ":" then
+			return ch1
+		end
+	end
+
+
+
 --
 -- Retrieve the file extension.
 --
@@ -101,17 +115,23 @@
 --
 
 	function path.getrelative(src, dst)
-		local result = ""
-		
 		-- normalize the two paths
-		src = path.getabsolute(src) .. "/"
-		dst = path.getabsolute(dst) .. "/"
+		src = path.getabsolute(src)
+		dst = path.getabsolute(dst)
 
 		-- same directory?
 		if (src == dst) then
 			return "."
 		end
 		
+		-- different drives? Must use absolute path
+		if path.getdrive(src) ~= path.getdrive(dst) then
+			return dst
+		end
+
+		src = src .. "/"
+		dst = dst .. "/"
+				
 		-- trim off the common directories from the front 
 		local i = src:find("/")
 		while (i) do
@@ -125,6 +145,7 @@
 		end
 
 		-- back up from dst to get to this common parent
+		local result = ""		
 		i = src:find("/")
 		while (i) do
 			result = result .. "../"

src/tools/gcc.lua

@@ -134,7 +134,7 @@
 	function premake.gcc.getincludedirs(includedirs)
 		local result = { }
 		for _,dir in ipairs(includedirs) do
-			table.insert(result, '-I "' .. dir .. '"')
+			table.insert(result, "-I" .. _MAKE.esc(dir))
 		end
 		return result
 	end

tests/test_path.lua

@@ -56,6 +56,21 @@
 	end
 		
 
+
+--
+-- path.getdrive() tests
+--
+
+	function T.path.getdrive_ReturnsNil_OnNotWindows()
+		test.isnil(path.getdrive("/hello"))
+	end
+	
+	function T.path.getdrive_ReturnsLetter_OnWindowsAbsolute()
+		test.isequal("x", path.getdrive("x:/hello"))
+	end
+	
+	
+	
 --
 -- path.getextension() tests
 --
@@ -97,6 +112,11 @@
 		test.isequal("obj/debug", path.getrelative("C:/Code/Premake4", "C:/Code/Premake4/obj/debug"))
 	end
 	
+	function T.path.getrelative_ReturnsAbsPath_OnDifferentDriveLetters()
+		test.isequal("D:/Files", path.getrelative("C:/Code/Premake4", "D:/Files"))
+	end
+	
+	
 
 --
 -- path.isabsolute() tests