fix os.nuldev on gcc/mingw

3 files changed, 36 insertions, 5 deletions

diff --git a/xmake/core/_xmake_main.lua b/xmake/core/_xmake_main.lua
index e9a23f491..a35d8b52b 100644
--- a/xmake/core/_xmake_main.lua
+++ b/xmake/core/_xmake_main.lua
@@ -27,7 +27,6 @@ xmake                   = xmake or {}
 xmake._ARGV             = _ARGV
 xmake._HOST             = _HOST
 xmake._ARCH             = _ARCH
-xmake._NULDEV           = _NULDEV
 xmake._VERSION          = _VERSION
 xmake._VERSION_SHORT    = _VERSION_SHORT
 xmake._PROGRAM_DIR      = _PROGRAM_DIR
diff --git a/xmake/core/base/os.lua b/xmake/core/base/os.lua
index 20114e2de..6275c4e15 100644
--- a/xmake/core/base/os.lua
+++ b/xmake/core/base/os.lua
@@ -691,9 +691,41 @@ function os.arch()
     return xmake._ARCH
 end
 
--- get the system null device
-function os.nuldev()
-    return xmake._NULDEV
+-- get the system null device 
+function os.nuldev(input)
+
+    -- init the output nuldev
+    if xmake._NULDEV_OUTPUT == nil then
+        if os.host() == "windows" then
+            xmake._NULDEV_OUTPUT = "nul"
+        else
+            xmake._NULDEV_OUTPUT = "/dev/null"
+        end
+    end
+
+    -- init the input nuldev
+    if xmake._NULDEV_INPUT == nil then
+        if os.host() == "windows" then
+            -- create an empty file
+            --
+            -- for fix issue on mingw:
+            -- $ gcc -fopenmp -S -o nul -xc nul
+            -- gcc: fatal error：input file ‘nul’ is the same as output file
+            -- 
+            local inputfile = os.tmpfile()
+            io.writefile(inputfile, "")
+            xmake._NULDEV_INPUT = inputfile
+        else
+            xmake._NULDEV_INPUT = "/dev/null"
+        end
+    end
+
+    -- get nuldev
+    if input then
+        return xmake._NULDEV_INPUT
+    else
+        return xmake._NULDEV_OUTPUT
+    end
 end
 
 -- get user agent
diff --git a/xmake/modules/detect/tools/gcc/has_flags.lua b/xmake/modules/detect/tools/gcc/has_flags.lua
index aa02557e8..fc7a8d2a6 100644
--- a/xmake/modules/detect/tools/gcc/has_flags.lua
+++ b/xmake/modules/detect/tools/gcc/has_flags.lua
@@ -105,7 +105,7 @@ function _check_try_running(flags, opt, islinker)
     end
     
     -- check flags for compiler
-    return try { function () os.runv(opt.program, table.join(flags, "-S", "-o", os.nuldev(), "-x" .. lang, os.nuldev())); return true end }
+    return try { function () os.runv(opt.program, table.join(flags, "-S", "-o", os.nuldev(), "-x" .. lang, os.nuldev(true))); return true end }
 end
 
 -- has_flags(flags)?