Fixed building on CygWin with clang gcc (#953)

* * Make Path:: use lowerCamel method names as per coding standard
* Small improvements to make closer to standard
* GetDirectoryName -> getParentDirectory - previous method name's action was somewhat unclear, hopefully this is better

* * Can build on clang and gcc on CygWin
* Fix problem on cygwin loading shared libraries
* Renamed Path::isRelative to ::hasRelativeElement because isRelative implies the path is 'relative to the current path' and which isn't quite what it does
* Documented how to build for CygWin

* * Fix small bug creating platform shared library name.
* Small typo fixes in building.md

1 files changed, 32 insertions, 7 deletions

diff --git a/premake5.lua b/premake5.lua
index dc3faa392..d939400d0 100644
--- a/premake5.lua
+++ b/premake5.lua
@@ -48,6 +48,7 @@
 -- From in the build directory you can use
 -- % premake5 --file=../premake5.lua --os=linux gmake 
 
+
 newoption {
    trigger     = "override-module",
    description = "(Optional) Specify a lua file that can override functions",
@@ -68,8 +69,19 @@ newoption {
    allowed     = { { "true", "True"}, { "false", "False" } }
 }
 
+newoption {
+   trigger     = "target-detail",
+   description = "(Optional) More specific target information",
+   value       = "string",
+   allowed     = { {"cygwin"}, {"mingw"} }
+}
+
 buildLocation = _OPTIONS["build-location"]
 executeBinary = (_OPTIONS["execute-binary"] == "true")
+targetDetail = _OPTIONS["target-detail"]
+
+-- Is true when the target is really windows (ie not something on top of windows like cygwin)
+local isTargetWindows = (os.target() == "windows") and not (targetDetail == "mingw" or targetDetail == "cygwin")
 
 overrideModule = {}
 local overrideModulePath = _OPTIONS["override-module"]
@@ -79,6 +91,18 @@ end
 
 targetName = "%{cfg.system}-%{cfg.platform:lower()}"
 
+if not (targetDetail == nil) then
+    targetName = targetDetail .. "-%{cfg.platform:lower()}"
+end
+
+-- This is needed for gcc, for the 'fileno' functions on cygwin
+-- _GNU_SOURCE makes realpath available in gcc
+if targetDetail == "cygwin" then
+    buildoptions { "-D_POSIX_SOURCE" }
+    filter { "toolset:gcc*" }
+        buildoptions { "-D_GNU_SOURCE" }
+end
+
 workspace "slang"
     -- We will support debug/release configuration and x86/x64 builds.
     configurations { "Debug", "Release" }
@@ -379,7 +403,7 @@ function example(name)
     links { "slang", "core", "gfx" }
 end
 
-if os.target() == "windows" then
+if isTargetWindows then
     --
     -- With all of these helper routines defined, we can now define the
     -- actual projects quite simply. For example, here is the entire
@@ -471,7 +495,7 @@ toolSharedLibrary "slang-reflection-test"
 -- TODO: Fix that requirement.
 --
 
-if os.target() == "windows" then    
+if isTargetWindows then    
     toolSharedLibrary "render-test"
         uuid "61F7EB00-7281-4BF3-9470-7C2EA92620C3"
         
@@ -501,17 +525,18 @@ tool "gfx"
 
     includedirs { ".", "external", "source", "external/imgui" }
 
-    filter { "system:windows" }
-
+    -- To special case that we may be building using cygwin on windows. If 'true windows' we build for dx12/vk and run the script
+    -- If not we assume it's a cygwin/mingw type situation and remove files that aren't appropriate
+    if isTargetWindows then
         systemversion "10.0.14393.0"
 
         -- For Windows targets, we want to copy d3dcompiler_47.dll,
         -- dxcompiler.dll, and dxil.dll from the Windows SDK redistributable
         -- directory into the output directory.
         postbuildcommands { '"$(SolutionDir)tools\\copy-hlsl-libs.bat" "$(WindowsSdkDir)Redist/D3D/%{cfg.platform:lower()}/" "%{cfg.targetdir}/"'}
-
-        filter { "system:not windows" }
-            removefiles { "tools/gfx/circular-resource-heap-d3d12.cpp", "tools/gfx/d3d-util.cpp", "tools/gfx/descriptor-heap-d3d12.cpp", "tools/gfx/render-d3d11.cpp", "tools/gfx/render-d3d12.cpp", "tools/gfx/render-gl.cpp", "tools/gfx/resource-d3d12.cpp", "tools/gfx/render-vk.cpp", "tools/gfx/vk-swap-chain.cpp", "tools/gfx/window.cpp" }
+    else
+         removefiles { "tools/gfx/circular-resource-heap-d3d12.cpp", "tools/gfx/d3d-util.cpp", "tools/gfx/descriptor-heap-d3d12.cpp", "tools/gfx/render-d3d11.cpp", "tools/gfx/render-d3d12.cpp", "tools/gfx/render-gl.cpp", "tools/gfx/resource-d3d12.cpp", "tools/gfx/render-vk.cpp", "tools/gfx/vk-swap-chain.cpp", "tools/gfx/window.cpp" }
+    end
 
 --
 -- The `slangc` command-line application is just a very thin wrapper