[meson] use the recommended way to generate hb-version.h

As https://github.com/harfbuzz/harfbuzz/pull/2532

src/gen-hb-version.py

@@ -1,31 +1,27 @@
 #!/usr/bin/env python3
 
-"usage: gen-hb-version.py 1.0.0 hb-version.h.in hb-version.h"
+"This tool is intended to be used from meson"
 
-import os, sys
+import os, sys, shutil
 
-os.chdir (os.path.dirname (__file__))
-
-if len (sys.argv) < 4:
+if len (sys.argv) < 5:
 	sys.exit(__doc__)
 
 version = sys.argv[1]
 major, minor, micro = version.split (".")
-input = sys.argv[2]
-output = sys.argv[3]
 
-with open (input, "r", encoding='utf-8') as input_file:
-	generated = (input_file.read ()
-		.replace ("@HB_VERSION_MAJOR@", major)
-		.replace ("@HB_VERSION_MINOR@", minor)
-		.replace ("@HB_VERSION_MICRO@", micro)
-		.replace ("@HB_VERSION@", version)
-		.encode ())
+OUTPUT = sys.argv[2]
+CURRENT_SOURCE_DIR = sys.argv[3]
+INPUT = sys.argv[4]
 
-	with open (output, "rb") as current_file:
-		current = current_file.read()
+with open (INPUT, "r", encoding='utf-8') as template:
+	with open (OUTPUT, "wb") as output:
+		output.write (template.read ()
+			.replace ("@HB_VERSION_MAJOR@", major)
+			.replace ("@HB_VERSION_MINOR@", minor)
+			.replace ("@HB_VERSION_MICRO@", micro)
+			.replace ("@HB_VERSION@", version)
+			.encode ())
 
-	# write only if is changed
-	if generated != current:
-		with open (output, "wb") as output_file:
-			output_file.write (generated)
+# copy it also to src/
+shutil.copyfile (OUTPUT, os.path.join (CURRENT_SOURCE_DIR, os.path.basename (OUTPUT)))

src/gen-ragel-artifacts.py

@@ -1,5 +1,7 @@
 #!/usr/bin/env python3
 
+"This tool is intended to be used from meson"
+
 import os, os.path, sys, subprocess, shutil, tempfile
 
 ragel = shutil.which ('ragel')
@@ -7,7 +9,7 @@ if not ragel:
 	exit ('You have to install ragel if you are going to develop HarfBuzz itself')
 
 if len (sys.argv) < 4:
-	exit ('This tool is intended to be used from meson')
+	exit (__doc__)
 
 OUTPUT = sys.argv[1]
 CURRENT_SOURCE_DIR = sys.argv[2]

src/meson.build

@@ -287,7 +287,8 @@ custom_target('hb-version.h',
   input: 'hb-version.h.in',
   output: 'hb-version.h',
   command: [find_program('gen-hb-version.py'), meson.project_version(),
-            'hb-version.h.in', 'hb-version.h'])
+            '@OUTPUT@', '@CURRENT_SOURCE_DIR@', '@INPUT@'],
+)
 
 ragel = find_program('ragel', required: false)
 if not ragel.found()