pkg: Check INCLUDE environment variable for MSVC

On Windows builds when --msvc-syntax is in use, add paths in the INCLUDE
environment variable to the system include search path and ignore the
various GCC environment variables. See
https://msdn.microsoft.com/en-us/library/73f9s62w.aspx for details.

https://bugs.freedesktop.org/show_bug.cgi?id=94729

3 files changed, 62 insertions, 20 deletions

diff --git a/check/check-system-flags b/check/check-system-flags
index 831dd0e..632496c 100755
--- a/check/check-system-flags
+++ b/check/check-system-flags
@@ -39,9 +39,28 @@ run_test --cflags system
 RESULT="-L/usr/lib -lsystem"
 run_test --libs system
 
-# Now check that the various compiler environment variables also update
-# the system include path
+# Now check that the various GCC environment variables also update the
+# system include path
 for var in CPATH C_INCLUDE_PATH CPP_INCLUDE_PATH; do
     RESULT=""
     eval $var=/usr/include run_test --cflags system
+
+    # Make sure these are not skipped in --msvc-syntax mode
+    if [ "$native_win32" = yes ]; then
+        RESULT="-I/usr/include"
+        eval $var=/usr/include run_test --cflags --msvc-syntax system
+    fi
+done
+
+# Check that the various MSVC environment variables also update the
+# system include path when --msvc-syntax is in use
+for var in INCLUDE; do
+    RESULT="-I/usr/include"
+    eval $var=/usr/include run_test --cflags system
+
+    # Make sure these are skipped in --msvc-syntax mode
+    if [ "$native_win32" = yes ]; then
+        RESULT=""
+        eval $var=/usr/include run_test --cflags --msvc-syntax system
+    fi
 done
diff --git a/pkg-config.1 b/pkg-config.1
index c8cec84..a147fc8 100644
--- a/pkg-config.1
+++ b/pkg-config.1
@@ -332,7 +332,15 @@ This is normally
 Additional paths to append to
 .IR "PKG_CONFIG_SYSTEM_INCLUDE_PATH" .
 These correspond to environment variables used by many compilers to
-affect the header search path.
+affect the header search path. These are ignored on Windows builds when
+\-\-msvc-syntax is in use.
+.TP
+.I "INCLUDE"
+Additional paths to append to
+.IR "PKG_CONFIG_SYSTEM_INCLUDE_PATH"
+on Windows builds when \-\-msvc-syntax is in use. This corresponds to
+the environment variable used by MSVC to add directories to the include
+file search path.
 .TP
 .I "PKG_CONFIG_ALLOW_SYSTEM_CFLAGS"
 Don't strip system paths out of Cflags. See
diff --git a/pkg.c b/pkg.c
index ae630c4..f29ecc7 100644
--- a/pkg.c
+++ b/pkg.c
@@ -621,6 +621,25 @@ add_env_variable_to_list (GList *list, const gchar *env)
   return list;
 }
 
+/* Well known compiler include path environment variables. These are
+ * used to find additional system include paths to remove. See
+ * https://gcc.gnu.org/onlinedocs/gcc/Environment-Variables.html. */
+static const gchar *gcc_include_envvars[] = {
+  "CPATH",
+  "C_INCLUDE_PATH",
+  "CPP_INCLUDE_PATH",
+  NULL
+};
+
+#ifdef G_OS_WIN32
+/* MSVC include path environment variables. See
+ * https://msdn.microsoft.com/en-us/library/73f9s62w.aspx. */
+static const gchar *msvc_include_envvars[] = {
+  "INCLUDE",
+  NULL
+};
+#endif
+
 static void
 verify_package (Package *pkg)
 {
@@ -634,6 +653,8 @@ verify_package (Package *pkg)
   GHashTable *visited;
   int count;
   const gchar *search_path;
+  const gchar **include_envvars;
+  const gchar **var;
 
   /* Be sure we have the required fields */
 
@@ -743,8 +764,8 @@ verify_package (Package *pkg)
   
   g_list_free (requires);
 
-  /* We make a list of system directories that gcc expects so we can remove
-   * them.
+  /* We make a list of system directories that compilers expect so we
+   * can remove them.
    */
 
   search_path = g_getenv ("PKG_CONFIG_SYSTEM_INCLUDE_PATH");
@@ -756,22 +777,16 @@ verify_package (Package *pkg)
 
   system_directories = add_env_variable_to_list (system_directories, search_path);
 
-  search_path = g_getenv ("CPATH");
-  if (search_path != NULL)
-    {
-      system_directories = add_env_variable_to_list (system_directories, search_path);
-    }
-
-  search_path = g_getenv ("C_INCLUDE_PATH");
-  if (search_path != NULL)
-    {
-      system_directories = add_env_variable_to_list (system_directories, search_path);
-    }
-
-  search_path = g_getenv ("CPLUS_INCLUDE_PATH");
-  if (search_path != NULL)
+#ifdef G_OS_WIN32
+  include_envvars = msvc_syntax ? msvc_include_envvars : gcc_include_envvars;
+#else
+  include_envvars = gcc_include_envvars;
+#endif
+  for (var = include_envvars; *var != NULL; var++)
     {
-      system_directories = add_env_variable_to_list (system_directories, search_path);
+      search_path = g_getenv (*var);
+      if (search_path != NULL)
+        system_directories = add_env_variable_to_list (system_directories, search_path);
     }
 
   count = 0;