Add new include_arch/config.install.include_arch installation location

It is mean for target architecture-specific headers.

3 files changed, 114 insertions, 74 deletions

diff --git a/NEWS b/NEWS
index ef9a8fd..6a7cbcd 100644
--- a/NEWS
+++ b/NEWS
@@ -49,6 +49,22 @@ Version 0.16.0
     For details, see the print_diag() API description in diagnostics.hxx. See
     also GH issue #40 for additional background/details.
 
+  * New include_arch installation location and the corresponding
+    config.install.include_arch configuration variable.
+
+    This location is meant for architecture-specific files, such as
+    configuration headers. By default it's the same as the standard include
+    location but can be configured by the user to a different value (for
+    example, /usr/include/x86_64-linux-gnu/) for platforms that support
+    multiple architectures from the same installation location. This is how
+    one would normally use it from a buildfile:
+
+    # The configuration header may contain target architecture-specific
+    # information so install it into include_arch/ instead of include/.
+    #
+    h{*}:      install = include/libhello/
+    h{config}: install = include_arch/libhello/
+
   * The in.substitution variable has been renamed to in.mode.
 
     The original name is still recognized for backwards compatibility.
diff --git a/doc/manual.cli b/doc/manual.cli
index ad440c1..5a2d35b 100644
--- a/doc/manual.cli
+++ b/doc/manual.cli
@@ -2312,36 +2312,39 @@ If the value of the \c{install} variable is not \c{false}, then it is normally
 a relative path with the first path component being one of these names:
 
 \
-name        default                         override
-----        -------                         --------
+name          default                       override
+----          -------                       --------
 root                                        config.install.root
 
-data_root   root/                           config.install.data_root
-exec_root   root/                           config.install.exec_root
+data_root     root/                         config.install.data_root
+exec_root     root/                         config.install.exec_root
 
-bin         exec_root/bin/                  config.install.bin
-sbin        exec_root/sbin/                 config.install.sbin
-lib         exec_root/lib/                  config.install.lib
-libexec     exec_root/libexec/<project>/    config.install.libexec
-pkgconfig   lib/pkgconfig/                  config.install.pkgconfig
+bin           exec_root/bin/                config.install.bin
+sbin          exec_root/sbin/               config.install.sbin
+lib           exec_root/lib/                config.install.lib
+libexec       exec_root/libexec/<project>/  config.install.libexec
+pkgconfig     lib/pkgconfig/                config.install.pkgconfig
 
-etc         data_root/etc/                  config.install.etc
-include     data_root/include/              config.install.include
-share       data_root/share/                config.install.share
-data        share/<project>/                config.install.data
+etc           data_root/etc/                config.install.etc
+include       data_root/include/            config.install.include
+include_arch  include/                      config.install.include_arch
+share         data_root/share/              config.install.share
+data          share/<project>/              config.install.data
 
-doc         share/doc/<project>/            config.install.doc
-legal       doc/                            config.install.legal
-man         share/man/                      config.install.man
-man<N>      man/man<N>/                     config.install.man<N>
+doc           share/doc/<project>/          config.install.doc
+legal         doc/                          config.install.legal
+man           share/man/                    config.install.man
+man<N>        man/man<N>/                   config.install.man<N>
 \
 
 Let's see what's going on here: The default install directory tree is derived
 from the \c{config.install.root} value but the location of each node in this
 tree can be overridden by the user that installs our project using the
-corresponding \c{config.install.*} variables. In our \c{buildfiles}, in turn,
-we use the node names instead of actual directories. As an example, here is a
-\c{buildfile} fragment from the source directory of our \c{libhello} project:
+corresponding \c{config.install.*} variables (see the \l{#module-install
+\c{install}} module documentation for details on their meaning). In our
+\c{buildfiles}, in turn, we use the node names instead of actual
+directories. As an example, here is a \c{buildfile} fragment from the source
+directory of our \c{libhello} project:
 
 \
 hxx{*}:
@@ -6133,28 +6136,45 @@ of the Introduction, the \c{install} module defines the following standard
 installation locations:
 
 \
-name        default                                 config.* override
-----        -------                                 -----------------
-root                                                install.root
+name          default                                 config.install.*
+                                                      (c.i.*) override
+----          -------                                 ----------------
+root                                                  c.i.root
 
-data_root   root/                                   install.data_root
-exec_root   root/                                   install.exec_root
+data_root     root/                                   c.i.data_root
+exec_root     root/                                   c.i.exec_root
 
-bin         exec_root/bin/                          install.bin
-sbin        exec_root/sbin/                         install.sbin
-lib         exec_root/lib/<private>/                install.lib
-libexec     exec_root/libexec/<private>/<project>/  install.libexec
-pkgconfig   lib/pkgconfig/                          install.pkgconfig
+bin           exec_root/bin/                          c.i.bin
+sbin          exec_root/sbin/                         c.i.sbin
+lib           exec_root/lib/<private>/                c.i.lib
+libexec       exec_root/libexec/<private>/<project>/  c.i.libexec
+pkgconfig     lib/pkgconfig/                          c.i.pkgconfig
 
-etc         data_root/etc/                          install.etc
-include     data_root/include/<private>/            install.include
-share       data_root/share/                        install.share
-data        share/<private>/<project>/              install.data
+etc           data_root/etc/                          c.i.etc
+include       data_root/include/<private>/            c.i.include
+include_arch  include/                                c.i.include_arch
+share         data_root/share/                        c.i.share
+data          share/<private>/<project>/              c.i.data
 
-doc         share/doc/<private>/<project>/          install.doc
-legal       doc/                                    install.legal
-man         share/man/                              install.man
-man<N>      man/man<N>/                             install.man<N>
+doc           share/doc/<private>/<project>/          c.i.doc
+legal         doc/                                    c.i.legal
+man           share/man/                              c.i.man
+man<N>        man/man<N>/                             c.i.man<N>
+\
+
+The \c{include_arch} location is meant for architecture-specific files, such
+as configuration headers. By default it's the same as \c{include} but can be
+configured by the user to a different value (for example,
+\c{/usr/include/x86_64-linux-gnu/}) for platforms that support multiple
+architectures from the same installation location. This is how one would
+normally use it from a \c{buildfile}:
+
+\
+# The configuration header may contain target architecture-specific
+# information so install it into include_arch/ instead of include/.
+#
+h{*}:      install = include/libhello/
+h{config}: install = include_arch/libhello/
 \
 
 The \c{<project>}, \c{<version>}, and \c{<private>} substitutions in these
@@ -6175,7 +6195,9 @@ The private installation subdirectory is specified with the
 directory and may include multiple components. For example:
 
 \
-$ b install config.install.root=/usr/local/ config.install.private=hello/
+$ b install                         \
+    config.install.root=/usr/local/ \
+    config.install.private=hello/
 \
 
 \N|If you are relying on your system's dynamic linker defaults to
diff --git a/libbuild2/install/init.cxx b/libbuild2/install/init.cxx
index 0f8b1be..92c2790 100644
--- a/libbuild2/install/init.cxx
+++ b/libbuild2/install/init.cxx
@@ -285,24 +285,25 @@ namespace build2
     //
 #define DIR(N, V) static const dir_path dir_##N (V)
 
-    DIR (data_root,  dir_path ("root"));
-    DIR (exec_root,  dir_path ("root"));
-
-    DIR (sbin,       dir_path ("exec_root") /= "sbin");
-    DIR (bin,        dir_path ("exec_root") /= "bin");
-    DIR (lib,       (dir_path ("exec_root") /= "lib") /= "<private>");
-    DIR (libexec,  ((dir_path ("exec_root") /= "libexec") /= "<private>") /= "<project>");
-    DIR (pkgconfig,  dir_path ("lib")       /= "pkgconfig");
-
-    DIR (etc,        dir_path ("data_root") /= "etc");
-    DIR (include,   (dir_path ("data_root") /= "include") /= "<private>");
-    DIR (share,      dir_path ("data_root") /= "share");
-    DIR (data,      (dir_path ("share")     /= "<private>") /= "<project>");
-
-    DIR (doc,      ((dir_path ("share")     /= "doc") /= "<private>") /= "<project>");
-    DIR (legal,      dir_path ("doc"));
-    DIR (man,        dir_path ("share")     /= "man");
-    DIR (man1,       dir_path ("man")       /= "man1");
+    DIR (data_root,     dir_path ("root"));
+    DIR (exec_root,     dir_path ("root"));
+
+    DIR (sbin,          dir_path ("exec_root") /= "sbin");
+    DIR (bin,           dir_path ("exec_root") /= "bin");
+    DIR (lib,          (dir_path ("exec_root") /= "lib") /= "<private>");
+    DIR (libexec,     ((dir_path ("exec_root") /= "libexec") /= "<private>") /= "<project>");
+    DIR (pkgconfig,     dir_path ("lib")       /= "pkgconfig");
+
+    DIR (etc,           dir_path ("data_root") /= "etc");
+    DIR (include,      (dir_path ("data_root") /= "include") /= "<private>");
+    DIR (include_arch,  dir_path ("include"));
+    DIR (share,         dir_path ("data_root") /= "share");
+    DIR (data,         (dir_path ("share")     /= "<private>") /= "<project>");
+
+    DIR (doc,         ((dir_path ("share")     /= "doc") /= "<private>") /= "<project>");
+    DIR (legal,         dir_path ("doc"));
+    DIR (man,           dir_path ("share")     /= "man");
+    DIR (man1,          dir_path ("man")       /= "man1");
 
 #undef DIR
 
@@ -583,28 +584,29 @@ namespace build2
 
         // Global config.install.* values.
         //
-        set_dir (s, p, rs, "",          abs_dir_path (), false, "644", "755", cmd);
+        set_dir (s, p, rs, "",             abs_dir_path (), false, "644", "755", cmd);
 
-        set_dir (s, p, rs, "root",      abs_dir_path ());
+        set_dir (s, p, rs, "root",         abs_dir_path ());
 
-        set_dir (s, p, rs, "data_root", dir_data_root);
-        set_dir (s, p, rs, "exec_root", dir_exec_root, false, "755");
+        set_dir (s, p, rs, "data_root",    dir_data_root);
+        set_dir (s, p, rs, "exec_root",    dir_exec_root, false, "755");
 
-        set_dir (s, p, rs, "sbin",      dir_sbin);
-        set_dir (s, p, rs, "bin",       dir_bin);
-        set_dir (s, p, rs, "lib",       dir_lib);
-        set_dir (s, p, rs, "libexec",   dir_libexec);
-        set_dir (s, p, rs, "pkgconfig", dir_pkgconfig, false, "644");
+        set_dir (s, p, rs, "sbin",         dir_sbin);
+        set_dir (s, p, rs, "bin",          dir_bin);
+        set_dir (s, p, rs, "lib",          dir_lib);
+        set_dir (s, p, rs, "libexec",      dir_libexec);
+        set_dir (s, p, rs, "pkgconfig",    dir_pkgconfig, false, "644");
 
-        set_dir (s, p, rs, "etc",       dir_etc);
-        set_dir (s, p, rs, "include",   dir_include);
-        set_dir (s, p, rs, "share",     dir_share);
-        set_dir (s, p, rs, "data",      dir_data);
+        set_dir (s, p, rs, "etc",          dir_etc);
+        set_dir (s, p, rs, "include",      dir_include);
+        set_dir (s, p, rs, "include_arch", dir_include_arch);
+        set_dir (s, p, rs, "share",        dir_share);
+        set_dir (s, p, rs, "data",         dir_data);
 
-        set_dir (s, p, rs, "doc",       dir_doc);
-        set_dir (s, p, rs, "legal",     dir_legal);
-        set_dir (s, p, rs, "man",       dir_man);
-        set_dir (s, p, rs, "man1",      dir_man1);
+        set_dir (s, p, rs, "doc",          dir_doc);
+        set_dir (s, p, rs, "legal",        dir_legal);
+        set_dir (s, p, rs, "man",          dir_man);
+        set_dir (s, p, rs, "man1",         dir_man1);
       }
 
       // Configure "installability" for built-in target types.