[bug#51241] [PATCH v2 1/1] gnu: ragel: Fix build of knot on aarch64-linux.

[Simon South]

Apply a patch backported from Ragel's "ragel-6" branch that allows it to
reliably generate usable code on systems such as aarch64-linux where the C/C++
"char" type is unsigned by default, fixing the build of Knot on these systems.

* gnu/packages/patches/ragel-decide-signedness-of-char.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/ragel.scm (ragel)[source]: Apply it.
---
 gnu/local.mk                                  |  1 +
 .../ragel-decide-signedness-of-char.patch     | 42 +++++++++++++++++++
 gnu/packages/ragel.scm                        |  7 +++-
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/ragel-decide-signedness-of-char.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index 208875754b..2b66d7c07c 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1717,6 +1717,7 @@ dist_patch_DATA =                                         
\
   %D%/packages/patches/quassel-qt-514-compat.patch             \
   %D%/packages/patches/quickswitch-fix-dmenu-check.patch       \
   %D%/packages/patches/qtwebkit-pbutils-include.patch          \
+  %D%/packages/patches/ragel-decide-signedness-of-char.patch   \
   %D%/packages/patches/randomjungle-disable-static-build.patch \
   %D%/packages/patches/rapicorn-isnan.patch                    \
   %D%/packages/patches/rapidjson-gcc-compat.patch              \
diff --git a/gnu/packages/patches/ragel-decide-signedness-of-char.patch 
b/gnu/packages/patches/ragel-decide-signedness-of-char.patch
new file mode 100644
index 0000000000..b3b2bf958a
--- /dev/null
+++ b/gnu/packages/patches/ragel-decide-signedness-of-char.patch
@@ -0,0 +1,42 @@
+From 2e638fccd81e96ce09841adc4b295b5ce694ea73 Mon Sep 17 00:00:00 2001
+From: Adrian Thurston <thurston@colm.net>
+Date: Sat, 6 Nov 2021 12:20:05 -0700
+Subject: [PATCH] C char type: decide signedness of char based on CHAR_MIN
+
+Previously had char fixed to signed char, this is not useful on ARM as it does
+not align with the host type. Instead, decide at runtime (or probably compile
+time) if char is signed or not.
+---
+ ragel/common.cpp | 16 ++++++++--------
+ 1 file changed, 8 insertions(+), 8 deletions(-)
+
+diff --git a/ragel/common.cpp b/ragel/common.cpp
+index 8e9f8ed0..55875c06 100644
+--- a/ragel/common.cpp
++++ b/ragel/common.cpp
+@@ -27,14 +27,14 @@
+ 
+ HostType hostTypesC[] =
+ {
+-      { "char",     0,       "char",    true,   true,  false,  CHAR_MIN,  
CHAR_MAX,   0, 0,              sizeof(char) },
+-      { "unsigned", "char",  "uchar",   false,  true,  false,  0, 0,          
        0,     UCHAR_MAX,  sizeof(unsigned char) },
+-      { "short",    0,       "short",   true,   true,  false,  SHRT_MIN,  
SHRT_MAX,   0, 0,              sizeof(short) },
+-      { "unsigned", "short", "ushort",  false,  true,  false,  0, 0,          
        0,     USHRT_MAX,  sizeof(unsigned short) },
+-      { "int",      0,       "int",     true,   true,  false,  INT_MIN,   
INT_MAX,    0, 0,              sizeof(int) },
+-      { "unsigned", "int",   "uint",    false,  true,  false,  0, 0,          
        0,     UINT_MAX,   sizeof(unsigned int) },
+-      { "long",     0,       "long",    true,   true,  false,  LONG_MIN,  
LONG_MAX,   0, 0,              sizeof(long) },
+-      { "unsigned", "long",  "ulong",   false,  true,  false,  0, 0,          
        0,     ULONG_MAX,  sizeof(unsigned long) }
++      { "char",     0,       "char",    (CHAR_MIN != 0), true,  false,  
SCHAR_MIN, SCHAR_MAX,  0, UCHAR_MAX, sizeof(char) },
++      { "unsigned", "char",  "uchar",   false,           true,  false,  0, 0, 
                 0, UCHAR_MAX, sizeof(unsigned char) },
++      { "short",    0,       "short",   true,            true,  false,  
SHRT_MIN,  SHRT_MAX,   0, 0,         sizeof(short) },
++      { "unsigned", "short", "ushort",  false,           true,  false,  0, 0, 
                 0, USHRT_MAX, sizeof(unsigned short) },
++      { "int",      0,       "int",     true,            true,  false,  
INT_MIN,   INT_MAX,    0, 0,         sizeof(int) },
++      { "unsigned", "int",   "uint",    false,           true,  false,  0, 0, 
                 0, UINT_MAX,  sizeof(unsigned int) },
++      { "long",     0,       "long",    true,            true,  false,  
LONG_MIN,  LONG_MAX,   0, 0,         sizeof(long) },
++      { "unsigned", "long",  "ulong",   false,           true,  false,  0, 0, 
                 0, ULONG_MAX, sizeof(unsigned long) }
+ };
+ 
+ #define S8BIT_MIN  -128
+-- 
+2.33.1
+
diff --git a/gnu/packages/ragel.scm b/gnu/packages/ragel.scm
index 1d9b67a6e0..8b5100330a 100644
--- a/gnu/packages/ragel.scm
+++ b/gnu/packages/ragel.scm
@@ -34,7 +34,12 @@ (define-public ragel
                                   version ".tar.gz"))
               (sha256
                (base32
-                "0gvcsl62gh6sg73nwaxav4a5ja23zcnyxncdcdnqa2yjcpdnw5az"))))
+                "0gvcsl62gh6sg73nwaxav4a5ja23zcnyxncdcdnqa2yjcpdnw5az"))
+              (patches
+               (search-patches
+                ;; A backported fix for aarch64-linux, where the C/C++ "char"
+                ;; type is unsigned by default.
+                "ragel-decide-signedness-of-char.patch"))))
     (build-system gnu-build-system)
     (home-page "https://www.colm.net/open-source/ragel/";)
     (synopsis "State machine compiler")
-- 
2.33.1