[PATCH v2 3/4] meson: add support for 'hdr-check'

[Karthik Nayak <karthik.188@gmail.com>]

The Makefile supports a target called 'hdr-check', which checks if
individual header files can be independently compiled. Let's port this
functionality to meson, our new build system too. The implementation
resembles that of the Makefile and provides the same check.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
---
 meson.build | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)

diff --git a/meson.build b/meson.build
index 790d178007..6fce1aa618 100644
--- a/meson.build
+++ b/meson.build
@@ -655,6 +655,12 @@ if git.found()
   endforeach
 endif
 
+headers_generated = [
+  'command-list.h',
+  'config-list.h',
+  'hook-list.h'
+]
+
 if not get_option('breaking_changes')
   builtin_sources += 'builtin/pack-redundant.c'
 endif
@@ -1995,6 +2001,107 @@ endif
 
 subdir('contrib')
 
+headers_check_exclude = headers_generated
+headers_check_exclude += [
+  'compat/apple-common-crypto.h',
+  'compat/bswap.h',
+  'compat/compiler.h',
+  'compat/disk.h',
+  'compat/fsmonitor/fsm-darwin-gcc.h',
+  'compat/fsmonitor/fsm-health.h',
+  'compat/fsmonitor/fsm-listen.h',
+  'compat/mingw.h',
+  'compat/msvc.h',
+  'compat/nedmalloc/malloc.c.h',
+  'compat/nedmalloc/nedmalloc.h',
+  'compat/nonblock.h',
+  'compat/obstack.h',
+  'compat/poll/poll.h',
+  'compat/precompose_utf8.h',
+  'compat/regex/regex.h',
+  'compat/regex/regex_internal.h',
+  'compat/sha1-chunked.h',
+  'compat/terminal.h',
+  'compat/vcbuild/include/sys/param.h',
+  'compat/vcbuild/include/sys/time.h',
+  'compat/vcbuild/include/sys/utime.h',
+  'compat/vcbuild/include/unistd.h',
+  'compat/vcbuild/include/utime.h',
+  'compat/win32.h',
+  'compat/win32/alloca.h',
+  'compat/win32/dirent.h',
+  'compat/win32/lazyload.h',
+  'compat/win32/path-utils.h',
+  'compat/win32/pthread.h',
+  'compat/win32/syslog.h',
+  'compat/zlib-compat.h',
+  't/unit-tests/clar/clar.h',
+  't/unit-tests/clar/clar/fixtures.h',
+  't/unit-tests/clar/clar/fs.h',
+  't/unit-tests/clar/clar/print.h',
+  't/unit-tests/clar/clar/sandbox.h',
+  't/unit-tests/clar/clar/summary.h',
+  't/unit-tests/clar/test/clar_test.h',
+  'unicode-width.h',
+  'xdiff/xdiff.h',
+  'xdiff/xdiffi.h',
+  'xdiff/xemit.h',
+  'xdiff/xinclude.h',
+  'xdiff/xmacros.h',
+  'xdiff/xprepare.h',
+  'xdiff/xtypes.h',
+  'xdiff/xutils.h',
+]
+
+if sha1_backend != 'openssl'
+  headers_check_exclude += 'sha1/openssl.h'
+endif
+if sha256_backend != 'openssl'
+  headers_check_exclude += 'sha256/openssl.h'
+endif
+if sha256_backend != 'nettle'
+  headers_check_exclude += 'sha256/nettle.h'
+endif
+if sha256_backend != 'gcrpyt'
+  headers_check_exclude += 'sha256/gcrypt.h'
+endif
+
+if headers.length() != 0 and compiler.get_argument_syntax() == 'gcc'
+  hco_targets = []
+  foreach h : headers
+    if headers_check_exclude.contains(h)
+      continue
+    endif
+
+    hcc = custom_target(
+      input: h,
+      output: h.underscorify() + 'cc',
+      command: [
+        shell,
+        '-c',
+        'echo \'#include "git-compat-util.h"\' > @OUTPUT@ && echo -n \'#include "' + h + '"\' >> @OUTPUT@'
+      ]
+    )
+
+    hco = custom_target(
+      input: hcc,
+      output: h.underscorify().replace('.h', '.hco'),
+      command: [
+        compiler.cmd_array(),
+        libgit_c_args,
+        '-I', meson.project_source_root(),
+        '-I', meson.project_source_root() / 't/unit-tests',
+        '-o', '/dev/null',
+        '-c', '-xc',
+        '@INPUT@'
+      ]
+    )
+    hco_targets += hco
+  endforeach
+
+  alias_target('hdr-check', hco_targets)
+endif
+
 foreach key, value : {
   'DIFF': diff.full_path(),
   'GIT_SOURCE_DIR': meson.project_source_root(),

-- 
2.48.1