[build] Linux fixes.

build.cake

@@ -39,7 +39,7 @@ Task("Build-Binder")
 Task("Generate-Project-Files")
     .Does(() =>
     {
-        var os = IsRunningOnWindows() ? "windows" : "macosx";
+        var os = IsRunningOnWindows() ? "windows" : IsRunningOnMacOS() ? "macosx" : "linux";
         Premake(File("./build/premake5.lua"), $"--outdir=.. --os={os}", "vs2015");
     });
 

build/Tests.cake

@@ -91,7 +91,7 @@ Task("Generate-C")
     .IsDependentOn("Build-FSharp-Generic")
     .Does(() =>
     {
-        var platform = IsRunningOnWindows() ? "Windows" : "macOS";
+        var platform = IsRunningOnWindows() ? "Windows" : IsRunningOnMacOS() ? "macOS" : "Linux";
         var output = commonDir + Directory("c");
         Exec(embeddinator, $"-gen=c -out={output} -platform={platform} -target=shared -verbose {managedDll} {fsharpManagedDll}");
     });
@@ -101,7 +101,7 @@ Task("Build-C-Tests")
     .Does(() =>
     {
         // Generate native project build files using Premake.
-        var os = IsRunningOnWindows() ? "--os=windows" : "--os=macosx";
+        var os = IsRunningOnWindows() ? "--os=windows" : IsRunningOnMacOS() ? "--os=macosx" : "--os=linux";
         var action = IsRunningOnWindows() ? "vs2015" : "gmake";
         Premake(commonDir + File("premake5.lua"), os, action);
 
@@ -162,7 +162,7 @@ Task("Generate-Java")
     .IsDependentOn("Build-Managed")
     .Does(() =>
     {
-        var platform = IsRunningOnWindows() ? "Windows" : "macOS";
+        var platform = IsRunningOnWindows() ? "Windows" : IsRunningOnMacOS() ? "macOS" : "Linux";
         var output = mkDir + Directory("java");
         Exec(embeddinator, $"-gen=Java -out={output} -platform={platform} -compile -target=shared {managedDll}");
     });

build/Utils.cake

@@ -1,3 +1,8 @@
+bool IsRunningOnMacOS()
+{
+    return true;
+}
+
 void Exec(string path, ProcessSettings settings)
 {
     if (path.EndsWith(".exe") && !IsRunningOnWindows())
@@ -24,6 +29,6 @@ void Exec(string path, string args = "", string workingDir = ".")
 void Premake(string file, string args, string action)
 {
     var premakePath = Directory("./external/CppSharp/build/") + (IsRunningOnWindows() ?
-        File("premake5.exe") : File("premake5-osx"));
+        File("premake5.exe") : IsRunningOnMacOS() ? File("premake5-osx") : File("premake5-linux-64"));
     Exec(premakePath, $"--file={file} {args} {action}");
 }

build/premake5.lua

@@ -18,7 +18,7 @@ function managed_project(name)
   language "C#"
   location ("%{wks.location}/build/projects")
 
-  if not os.istarget("macosx") then
+  if os.istarget("windows") then
     filter { "action:vs*" }
       location "."
     filter {}