From 61fb2262e71a044198b8b18872a802036c332d80 Mon Sep 17 00:00:00 2001
From: Eli Schwartz <eschwartz@gentoo.org>
Date: Fri, 25 Apr 2025 01:25:40 -0400
Subject: [PATCH] meson: simplify and parameterize various standard function
 checks

This is repetitive logic. We either want to use some -lc function, or if
it is not available we define it as -DNO_XXX and usually (but not
always) provide some custom compatibility impl instead.

Checking the intent of each block when reading through the file is slow
and not very DRY. Switch to taking an array of checkable functions
instead.

Not all functions are straightforward to move, since different macro
prefixes are used.

Signed-off-by: Eli Schwartz <eschwartz@gentoo.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 meson.build | 85 ++++++++++++++++++-----------------------------------
 1 file changed, 29 insertions(+), 56 deletions(-)

diff --git a/meson.build b/meson.build
index c47cb79af0..ed0359b9c9 100644
--- a/meson.build
+++ b/meson.build
@@ -1133,11 +1133,6 @@ else
   build_options_config.set('NO_UNIX_SOCKETS', '1')
 endif
 
-if not compiler.has_function('pread')
-  libgit_c_args += '-DNO_PREAD'
-  libgit_sources += 'compat/pread.c'
-endif
-
 if host_machine.system() == 'darwin'
   libgit_sources += 'compat/precompose_utf8.c'
   libgit_c_args += '-DPRECOMPOSE_UNICODE'
@@ -1290,23 +1285,39 @@ if not compiler.has_member('struct passwd', 'pw_gecos', prefix: '#include <pwd.h
   libgit_c_args += '-DNO_GECOS_IN_PWENT'
 endif
 
-if compiler.has_function('sync_file_range')
-  libgit_c_args += '-DHAVE_SYNC_FILE_RANGE'
-endif
+checkfuncs = {
+  'strcasestr' : ['strcasestr.c'],
+  'memmem' : ['memmem.c'],
+  'strlcpy' : ['strlcpy.c'],
+  'strtoull' : [],
+  'setenv' : ['setenv.c'],
+  'mkdtemp' : ['mkdtemp.c'],
+  'initgroups' : [],
+  'strtoumax' : ['strtoumax.c', 'strtoimax.c'],
+  'pread' : ['pread.c'],
+}
 
-if not compiler.has_function('strcasestr')
-  libgit_c_args += '-DNO_STRCASESTR'
-  libgit_sources += 'compat/strcasestr.c'
+if host_machine.system() == 'windows'
+  libgit_c_args += '-DUSE_WIN32_MMAP'
+else
+  checkfuncs += {
+    'mmap' : ['mmap.c'],
+    # provided by compat/mingw.c.
+    'unsetenv' : ['unsetenv.c'],
+  }
 endif
 
-if not compiler.has_function('memmem')
-  libgit_c_args += '-DNO_MEMMEM'
-  libgit_sources += 'compat/memmem.c'
-endif
+foreach func, impls : checkfuncs
+  if not compiler.has_function(func)
+    libgit_c_args += '-DNO_' + func.to_upper()
+    foreach impl : impls
+      libgit_sources += 'compat/' + impl
+    endforeach
+  endif
+endforeach
 
-if not compiler.has_function('strlcpy')
-  libgit_c_args += '-DNO_STRLCPY'
-  libgit_sources += 'compat/strlcpy.c'
+if compiler.has_function('sync_file_range')
+  libgit_c_args += '-DHAVE_SYNC_FILE_RANGE'
 endif
 
 if not compiler.has_function('strdup')
@@ -1314,53 +1325,15 @@ if not compiler.has_function('strdup')
   libgit_sources += 'compat/strdup.c'
 endif
 
-if not compiler.has_function('strtoumax')
-  libgit_c_args += '-DNO_STRTOUMAX'
-  libgit_sources += [
-    'compat/strtoumax.c',
-    'compat/strtoimax.c',
-  ]
-endif
-
-if not compiler.has_function('strtoull')
-  libgit_c_args += '-DNO_STRTOULL'
-endif
-
-if not compiler.has_function('setenv')
-  libgit_c_args += '-DNO_SETENV'
-  libgit_sources += 'compat/setenv.c'
-endif
-
 if not compiler.has_function('qsort')
   libgit_c_args += '-DINTERNAL_QSORT'
 endif
 libgit_sources += 'compat/qsort_s.c'
 
-# unsetenv is provided by compat/mingw.c.
-if host_machine.system() != 'windows' and not compiler.has_function('unsetenv')
-  libgit_c_args += '-DNO_UNSETENV'
-  libgit_sources += 'compat/unsetenv.c'
-endif
-
-if not compiler.has_function('mkdtemp')
-  libgit_c_args += '-DNO_MKDTEMP'
-  libgit_sources += 'compat/mkdtemp.c'
-endif
-
-if not compiler.has_function('initgroups')
-  libgit_c_args += '-DNO_INITGROUPS'
-endif
-
 if compiler.has_function('getdelim')
   libgit_c_args += '-DHAVE_GETDELIM'
 endif
 
-if host_machine.system() == 'windows'
-  libgit_c_args += '-DUSE_WIN32_MMAP'
-elif not compiler.has_function('mmap')
-  libgit_c_args += '-DNO_MMAP'
-  libgit_sources += 'compat/mmap.c'
-endif
 
 if compiler.has_function('clock_gettime')
   libgit_c_args += '-DHAVE_CLOCK_GETTIME'
-- 
2.47.3