[glib-openssl] meson: Improve Visual Studio build experience

[Chun-wei Fan <fanchunwei src gnome org>]

commit d36e23ebb9e9233b9a812f01a3e1010c5c404687
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Mon Nov 27 15:30:32 2017 +0800

    meson: Improve Visual Studio build experience
    
    The OpenSSL build system does not generate pkg-config files for us, and
    crafting pkg-config files by hand may be tedious and error-prone, so add
    a fallback to check for the OpenSSL headers and libraries manually for
    Visual Studio builds.  As the .lib files for OpenSSL 1.1.x and 1.0.x
    (and earlier) are different, we need to determine the correct pair of
    .lib files that we want to link to later.
    
    Also, to clean things up a bit, just force-include
    msvc_recommended_pragmas.h instead of checking for the warning cflags on
    Visual Studio, as they exist on all the Visual Studio versions that we
    support.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=790886

 meson.build |   63 +++++++++++++++++++++++++++++++++++++++-------------------
 1 files changed, 42 insertions(+), 21 deletions(-)
---
diff --git a/meson.build b/meson.build
index 21286cb..dea3298 100644
--- a/meson.build
+++ b/meson.build
@@ -12,8 +12,46 @@ gio = dependency('gio-2.0', version: '>=' + glib_req)
 giomoduledir = gio.get_pkgconfig_variable('giomoduledir')
 gio_querymodules = find_program('gio-querymodules')
 
-openssl = dependency('openssl')
-# TODO: Handle finding on Win32
+# MSVC builds of OpenSSL does not generate pkg-config files,
+# so we check for it manually here in this case, if we can't find those files
+openssl = dependency('openssl', required: cc.get_id() != 'msvc')
+
+if not openssl.found()
+  # Based on the CMake check for OpenSSL in CURL's CMakeLists.txt,
+  # on which headers we should check for
+  cc.has_header('openssl/crypto.h')
+  cc.has_header('openssl/engine.h')
+  cc.has_header('openssl/err.h')
+  cc.has_header('openssl/pem.h')
+  cc.has_header('openssl/rsa.h')
+  cc.has_header('openssl/ssl.h')
+  cc.has_header('openssl/x509.h')
+  cc.has_header('openssl/rand.h')
+  cc.has_header('openssl/tls1.h')
+
+  # OpenSSL 1.1.x and 1.0.x (or earlier) have different .lib names,
+  # so we need to look for the correct pair
+
+  # Find either libcrypto.lib (1.1.x) or libeay32.lib (1.0.x or earlier) first
+  libcrypto = cc.find_library('libcrypto', required: false)
+  if not libcrypto.found()
+    libeay = cc.find_library('libeay32')
+  endif
+
+  # Find the corresponding SSL library depending on which crypto .lib we found
+  if libcrypto.found()
+    libssl = cc.find_library('libssl')
+  elif libeay.found()
+    ssleay = cc.find_library('ssleay32')
+  endif
+
+  # Now set the openssl dependency to the corresponding pair of .lib files that we found
+  if libcrypto.found()
+    openssl = [libcrypto, libssl]
+  else
+    openssl = [libeay, ssleay]
+  endif
+endif
 
 # Compiler flags
 if cc.get_id() == 'msvc'
@@ -21,25 +59,8 @@ if cc.get_id() == 'msvc'
   # from _Win32_Programming_ by Rector and Newcomer.  Taken from
   # glib's msvc_recommended_pragmas.h--please see that file for
   # the meaning of the warning codes used here
-  test_cflags = [
-    '-we4002', # too many actual parameters for macro
-    '-we4003', # not enough actual parameters for macro
-    '-w14010', # single-line comment contains line-continuation character
-    '-we4013', # 'function' undefined; assuming extern returning int
-    '-w14016', # no function return type; using int as default
-    '-we4020', # too many actual parameters
-    '-we4021', # too few actual parameters
-    '-we4027', # function declared without formal parameter list
-    '-we4029', # declared formal parameter list different from definition
-    '-we4033', # 'function' must return a value
-    '-we4035', # 'function' : no return value
-    '-we4045', # array bounds overflow
-    '-we4047', # different levels of indirection
-    '-we4049', # terminating line number emission
-    '-we4053', # an expression of type void was used as an operand
-    '-we4071', # no function prototype given
-    '-we4819', # the file contains a character that cannot be represented in the current code page
-  ]
+  test_cflags = []
+  add_project_arguments('/FImsvc_recommended_pragmas.h', language : 'c')
 else
   test_cflags = [
     '-ffast-math',