From 7806ec525eec83d250141a32cfa197949ea1a42b Mon Sep 17 00:00:00 2001
From: rockcavera <rockcavera@gmail.com>
Date: Wed, 8 Dec 2021 02:48:34 -0300
Subject: [PATCH] Making TCC work again on Windows --cpu:amd64 - fix #16326
 (#19221)

* fix #16326

* removing comments
---
 lib/system/io.nim | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/system/io.nim b/lib/system/io.nim
index 2ad43acdbb75..661d1a9ba1fd 100644
--- a/lib/system/io.nim
+++ b/lib/system/io.nim
@@ -109,8 +109,22 @@ when defined(windows):
   else:
     proc c_fseek(f: File, offset: int64, whence: cint): cint {.
       importc: "_fseeki64", header: "<stdio.h>", tags: [].}
-    proc c_ftell(f: File): int64 {.
-      importc: "_ftelli64", header: "<stdio.h>", tags: [].}
+    when defined(tcc):
+      proc c_fsetpos(f: File, pos: var int64): int32 {.
+        importc: "fsetpos", header: "<stdio.h>", tags: [].}
+      proc c_fgetpos(f: File, pos: var int64): int32 {.
+        importc: "fgetpos", header: "<stdio.h>", tags: [].}
+      proc c_telli64(f: cint): int64 {.
+        importc: "_telli64", header: "<io.h>", tags: [].}
+      proc c_ftell(f: File): int64 =
+        # Taken from https://pt.osdn.net/projects/mingw/scm/git/mingw-org-wsl/blobs/5.4-trunk/mingwrt/mingwex/stdio/ftelli64.c
+        result = -1'i64
+        var pos: int64
+        if c_fgetpos(f, pos) == 0 and c_fsetpos(f, pos) == 0:
+          result = c_telli64(c_fileno(f))
+    else:
+      proc c_ftell(f: File): int64 {.
+        importc: "_ftelli64", header: "<stdio.h>", tags: [].}
 else:
   proc c_fseek(f: File, offset: int64, whence: cint): cint {.
     importc: "fseeko", header: "<stdio.h>", tags: [].}