gnu: libcyaml: Fix build with libyaml 0.2.5.

* gnu/packages/patches/libcyaml-libyaml-compat.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/web.scm (libcyaml)[source](patches): New field.

gnu/local.mk

@@ -1230,6 +1230,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/libbonobo-activation-test-race.patch	\
   %D%/packages/patches/libcanberra-sound-theme-freedesktop.patch \
   %D%/packages/patches/libcanberra-wayland-crash.patch \
+  %D%/packages/patches/libcyaml-libyaml-compat.patch		\
   %D%/packages/patches/libgeotiff-adapt-test-script-for-proj-6.2.patch		\
   %D%/packages/patches/libgit2-mtime-0.patch			\
   %D%/packages/patches/libgnome-encoding.patch			\

gnu/packages/patches/libcyaml-libyaml-compat.patch

@@ -0,0 +1,51 @@
+Fix build against libyaml 0.2.5.
+
+Taken from upstream:
+https://github.com/tlsa/libcyaml/commit/0e947264b947f51f7ea785068637c4bfce5d4171
+
+diff --git a/test/units/save.c b/test/units/save.c
+--- a/test/units/save.c
++++ b/test/units/save.c
+@@ -3476,7 +3476,7 @@ static bool test_save_sequence_null_values_int(
+ 		ttest_report_ctx_t *report,
+ 		const cyaml_config_t *config)
+ {
+-	static const unsigned char ref[] =
++	static const unsigned char ref1[] =
+ 		"---\n"
+ 		"- 7\n"
+ 		"- 6\n"
+@@ -3487,6 +3487,18 @@ static bool test_save_sequence_null_values_int(
+ 		"- \n"
+ 		"- 0\n"
+ 		"...\n";
++	/* As of libyaml 0.2.5, trailing spaces are not emitted. */
++	static const unsigned char ref2[] =
++		"---\n"
++		"- 7\n"
++		"- 6\n"
++		"- 5\n"
++		"-\n"
++		"- 3\n"
++		"- 2\n"
++		"-\n"
++		"- 0\n"
++		"...\n";
+ 	static const int d[] = { 7, 6, 5, 4, 3, 2, 1, 0 };
+ 	static const int *data[] = { d + 0, d + 1, d + 2, NULL,
+ 	                             d + 4, d + 5, NULL, d + 7, };
+@@ -3515,11 +3527,12 @@ static bool test_save_sequence_null_values_int(
+ 		return ttest_fail(&tc, cyaml_strerror(err));
+ 	}
+ 
+-	if (len != YAML_LEN(ref) || memcmp(ref, buffer, len) != 0) {
++	if ((len != YAML_LEN(ref1) || memcmp(ref1, buffer, len) != 0) &&
++	    (len != YAML_LEN(ref2) || memcmp(ref2, buffer, len) != 0)) {
+ 		return ttest_fail(&tc, "Bad data:\n"
+ 				"EXPECTED (%zu):\n\n%.*s\n\n"
+ 				"GOT (%zu):\n\n%.*s\n",
+-				YAML_LEN(ref), YAML_LEN(ref), ref,
++				YAML_LEN(ref1), YAML_LEN(ref1), ref1,
+ 				len, len, buffer);
+ 	}
+ 

gnu/packages/web.scm

@@ -5081,6 +5081,7 @@ (define-public libcyaml
              (url "https://github.com/tlsa/libcyaml")
              (commit (string-append "v" version))))
        (file-name (git-file-name name version))
+       (patches (search-patches "libcyaml-yaml-compat.patch"))
        (sha256
         (base32 "0428p0rwq71nhh5nzcbapsbrjxa0x5l6h6ns32nxv7j624f0zd93"))))
     (build-system gnu-build-system)