Add force includes for SNC; allow configuration context proxy to be reset by exporter code

src/project/project.lua

@@ -208,6 +208,9 @@
 					return premake5.project.getrelative(cfg.project, cfg[key])
 				end
 				return cfg[key]
+			end,
+			__newindex = function(proxy, key, value)
+				cfg[key] = value
 			end
 		})
 

src/tools/snc.lua

@@ -14,17 +14,7 @@
 -- SNC flags for specific systems and architectures.
 --
 
-	snc.sysflags = {
-	}
-
-
---
--- Retrieve the CPPFLAGS for a specific configuration.
---
-
-	function snc.getcppflags(cfg)
-		return { "-MMD", "-MP" }
-	end
+	snc.sysflags = {}
 
 
 --
@@ -85,6 +75,7 @@
 -- These are the same as GCC
 --
 
+	snc.getcppflags = gcc.getcppflags
 	snc.getdefines = gcc.getdefines
 	snc.getincludedirs = gcc.getincludedirs
 	snc.getlinks = gcc.getlinks

tests/tools/test_snc.lua

@@ -129,3 +129,13 @@
 		test.isequal({ "generated.o" }, snc.getlinks(cfg))
 	end
 
+
+--
+-- Check handling of forced includes.
+--
+
+	function suite.forcedIncludeFiles()
+		forceincludes { "stdafx.h", "include/sys.h" }
+		prepare()
+		test.isequal({"-MMD", "-MP", '-include "stdafx.h"', '-include "include/sys.h"'}, snc.getcppflags(cfg))
+	end