[PATCH] Update get_standard_cache_dir for macOS

[Tom Tromey <tom@tromey.com>]

On macOS the usual cache directory is ~/Library/Caches.  This patch
changes get_standard_cache_dir to use that instead of XDG.

gdb/ChangeLog
2018-09-14  Tom Tromey  <tom@tromey.com>

	* common/pathstuff.c (get_standard_cache_dir): Use
	~/Library/Caches on macOS.
	* common/pathstuff.h (get_standard_cache_dir): Update comment.

gdb/doc/ChangeLog
2018-09-14  Tom Tromey  <tom@tromey.com>

	* gdb.texinfo (Index Files): Update for cache directory change on
	macOS.
---
 gdb/ChangeLog          |  6 ++++++
 gdb/common/pathstuff.c | 10 +++++++++-
 gdb/common/pathstuff.h | 10 +++++++---
 gdb/doc/ChangeLog      |  5 +++++
 gdb/doc/gdb.texinfo    | 12 ++++++++----
 5 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 49bcd9ff8a..59b47bd9aa 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2018-09-14  Tom Tromey  <tom@tromey.com>
+
+	* common/pathstuff.c (get_standard_cache_dir): Use
+	~/Library/Caches on macOS.
+	* common/pathstuff.h (get_standard_cache_dir): Update comment.
+
 2018-09-14  Tom Tromey  <tom@tromey.com>
 
 	* infcall.c (call_function_by_hand_dummy): Remove unnecessary
diff --git a/gdb/common/pathstuff.c b/gdb/common/pathstuff.c
index 2d9dcb25d4..3dd58e31aa 100644
--- a/gdb/common/pathstuff.c
+++ b/gdb/common/pathstuff.c
@@ -164,6 +164,13 @@ contains_dir_separator (const char *path)
 std::string
 get_standard_cache_dir ()
 {
+#ifdef __APPLE__
+#define HOME_CACHE_DIR "Library/Caches"
+#else
+#define HOME_CACHE_DIR ".cache"
+#endif
+
+#ifndef __APPLE__
   char *xdg_cache_home = getenv ("XDG_CACHE_HOME");
   if (xdg_cache_home != NULL)
     {
@@ -171,13 +178,14 @@ get_standard_cache_dir ()
       gdb::unique_xmalloc_ptr<char> abs (gdb_abspath (xdg_cache_home));
       return string_printf ("%s/gdb", abs.get ());
     }
+#endif
 
   char *home = getenv ("HOME");
   if (home != NULL)
     {
       /* Make sure the path is absolute and tilde-expanded.  */
       gdb::unique_xmalloc_ptr<char> abs (gdb_abspath (home));
-      return string_printf ("%s/.cache/gdb", abs.get ());
+      return string_printf ("%s/" HOME_CACHE_DIR "/gdb", abs.get ());
     }
 
   return {};
diff --git a/gdb/common/pathstuff.h b/gdb/common/pathstuff.h
index d1aa6b306c..a43b963651 100644
--- a/gdb/common/pathstuff.h
+++ b/gdb/common/pathstuff.h
@@ -53,10 +53,14 @@ extern bool contains_dir_separator (const char *path);
 /* Get the usual user cache directory for the current platform.
 
    On Linux, it follows the XDG Base Directory specification: use
-   $XDG_CACHE_HOME/gdb if the XDG_CACHE_HOME environment variable is defined,
-   otherwise $HOME/.cache.  The return value is absolute and tilde-expanded.
+   $XDG_CACHE_HOME/gdb if the XDG_CACHE_HOME environment variable is
+   defined, otherwise $HOME/.cache.
 
-   Return an empty string if neither XDG_CACHE_HOME or HOME are defined.  */
+   On macOS, it follows the local convention and uses
+   ~/Library/Caches/gdb.
+
+  The return value is absolute and tilde-expanded.  Return an empty
+  string if neither XDG_CACHE_HOME (on Linux) or HOME are defined.  */
 
 extern std::string get_standard_cache_dir ();
 
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 1a5c70bfc8..bb494362bc 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2018-09-14  Tom Tromey  <tom@tromey.com>
+
+	* gdb.texinfo (Index Files): Update for cache directory change on
+	macOS.
+
 2018-09-13  Simon Marchi  <simon.marchi@ericsson.com>
 
 	* python.texi (Objfiles In Python): Update gdb.objfiles() doc.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index efbec3debf..ad090ba17b 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -20128,10 +20128,14 @@ Enable or disable the use of the symbol index cache.
 
 @item set index-cache directory @var{directory}
 @itemx show index-cache directory
-Set/show the directory where index files will be saved.  By default, the index
-is cached in the @file{gdb} subdirectory of the directory pointed to by the
-@env{XDG_CACHE_HOME} environment variable, if it is defined, else in the
-@file{.cache/gdb} subdirectory of your home directory.
+Set/show the directory where index files will be saved.
+
+The default value for this directory depends on the host platform.  On
+most systems, the index is cached in the @file{gdb} subdirectory of
+the directory pointed to by the @env{XDG_CACHE_HOME} environment
+variable, if it is defined, else in the @file{.cache/gdb} subdirectory
+of your home directory.  However, on macOS, the index is cached in the
+@file{~/Library/Caches/gdb/}.
 
 There is no limit on the disk space used by index cache.  It is perfectly safe
 to delete the content of that directory to free up disk space.
-- 
2.17.1