From cbb288204d1adfd5269cb1e5ee69013546e268a7 Mon Sep 17 00:00:00 2001
From: Pierre Bourdon <delroth@gmail.com>
Date: Sun, 28 Jun 2020 11:12:52 +0200
Subject: [PATCH] file: backport patch to fix a 5.39 regression

This bug is causing diffoscope to fail to build with file 5.39.
---
 pkgs/tools/misc/file/default.nix                  |  6 ++++++
 pkgs/tools/misc/file/webassembly-format-fix.patch | 13 +++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 pkgs/tools/misc/file/webassembly-format-fix.patch

diff --git a/pkgs/tools/misc/file/default.nix b/pkgs/tools/misc/file/default.nix
index 730234998ed..8e284b25c08 100644
--- a/pkgs/tools/misc/file/default.nix
+++ b/pkgs/tools/misc/file/default.nix
@@ -12,6 +12,12 @@ stdenv.mkDerivation rec {
     sha256 = "1lgs2w2sgamzf27kz5h7pajz7v62554q21fbs11n4mfrfrm2hpgh";
   };
 
+  patches = [
+    # https://github.com/file/file/commit/85b7ab83257b3191a1a7ca044589a092bcef2bb3
+    # Without the RCS id change to avoid conflicts. Remove on next bump.
+    ./webassembly-format-fix.patch
+  ];
+
   nativeBuildInputs = stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) file;
   buildInputs = [ zlib ]
               ++ stdenv.lib.optional stdenv.hostPlatform.isWindows libgnurx;
diff --git a/pkgs/tools/misc/file/webassembly-format-fix.patch b/pkgs/tools/misc/file/webassembly-format-fix.patch
new file mode 100644
index 00000000000..5eca833e4d7
--- /dev/null
+++ b/pkgs/tools/misc/file/webassembly-format-fix.patch
@@ -0,0 +1,13 @@
+diff --git a/src/funcs.c b/src/funcs.c
+index 299b8f022..ecbfa28c5 100644
+--- a/src/funcs.c
++++ b/src/funcs.c
+@@ -93,7 +93,7 @@ file_checkfmt(char *msg, size_t mlen, const char *fmt)
+ 		if (*++p == '%')
+ 			continue;
+ 		// Skip uninteresting.
+-		while (strchr("0.'+- ", *p) != NULL)
++		while (strchr("#0.'+- ", *p) != NULL)
+ 			p++;
+ 		if (*p == '*') {
+ 			if (msg)