Subprojects can use meson.add_dist_script() if meson.version() >= 0.58.0

* meson.build:
* MSVC_NMake/meson.build:
* docs/docs/manual/meson.build:
* docs/docs/reference/meson.build:
Call add_dist_script() in a subproject, if meson.version() >= 0.58.0.
* tools/handle-built-files.py:
* tools/tutorial-custom-cmd.py:
Use MESON_PROJECT_DIST_ROOT if it exists, else MESON_DIST_ROOT.
It exists if meson.version() >= 0.58.0.

6 files changed, 26 insertions, 19 deletions

diff --git a/MSVC_NMake/meson.build b/MSVC_NMake/meson.build
index da56141..f9ddc35 100644
--- a/MSVC_NMake/meson.build
+++ b/MSVC_NMake/meson.build
@@ -1,6 +1,7 @@
 # MSVC_NMake
 
-# Input: pkg_conf_data, sigcxxconfig_h, project_build_root, python3
+# Input: pkg_conf_data, sigcxxconfig_h, project_build_root, python3,
+#        can_add_dist_script
 # Output: sigc_rc
 
 sigc_rc = configure_file(
@@ -19,10 +20,8 @@ configure_file(
 untracked_msvc_nmake = 'untracked' / 'MSVC_NMake'
 handle_built_files = project_source_root / 'tools' / 'handle-built-files.py'
 
-if not meson.is_subproject()
+if can_add_dist_script
   # Distribute built files.
-  # (add_dist_script() is not allowed in a subproject)
-
   meson.add_dist_script(
     python3.path(), handle_built_files, 'dist_gen_msvc_files',
     meson.current_build_dir(),
diff --git a/docs/docs/manual/meson.build b/docs/docs/manual/meson.build
index a90bb09..59e67e4 100644
--- a/docs/docs/manual/meson.build
+++ b/docs/docs/manual/meson.build
@@ -1,7 +1,7 @@
 # docs/docs/manual
 
 # input: install_datadir, sigcxx_pcname, tutorial_custom_cmd, python3,
-#        build_documentation, book_name
+#        build_documentation, book_name, can_add_dist_script
 # output: can_parse_and_validate, build_pdf_by_default, can_build_pdf,
 #         install_tutorialdir
 
@@ -77,9 +77,8 @@ if can_build_pdf
   )
 endif
 
-if not meson.is_subproject()
+if can_add_dist_script
   # Distribute built files.
-  # (add_dist_script() is not allowed in a subproject)
   meson.add_dist_script(
     python3.path(), tutorial_custom_cmd, 'dist_doc',
     doc_dist_dir,
diff --git a/docs/docs/reference/meson.build b/docs/docs/reference/meson.build
index 8bc659b..bdf944d 100644
--- a/docs/docs/reference/meson.build
+++ b/docs/docs/reference/meson.build
@@ -2,7 +2,8 @@
 
 # Input: project_build_root, project_source_root, sigcxx_pcname,
 #        sigcxx_api_version, build_documentation, source_h_files,
-#        hg_ccg_basenames, install_datadir, python3, doc_reference
+#        hg_ccg_basenames, install_datadir, python3, doc_reference,
+#        can_add_dist_script
 # Output: install_docdir, install_devhelpdir, book_name, tag_file
 
 # There are no built source files in libsigc++-3.0.
@@ -121,9 +122,8 @@ meson.add_install_script(
   docinstall_flags
 )
 
-if not meson.is_subproject()
+if can_add_dist_script
   # Distribute built files and files copied by mm-common-get.
-  # (add_dist_script() is not allowed in a subproject)
   meson.add_dist_script(
     python3.path(), doc_reference, 'dist_doc',
     doctool_dir,
diff --git a/meson.build b/meson.build
index 5f636ff..ab1aee0 100644
--- a/meson.build
+++ b/meson.build
@@ -220,6 +220,9 @@ sigcxxconfig_h = configure_file(
   install_dir: install_includeconfigdir,
 )
 
+# add_dist_script() is not allowed in a subproject if meson.version() < 0.58.0.
+can_add_dist_script = not meson.is_subproject() or meson.version().version_compare('>= 0.58.0')
+
 #subdir('cmake')
 subdir('MSVC_NMake')
 subdir('sigc++')
@@ -228,22 +231,22 @@ subdir('tests')
 subdir('docs/docs/reference')
 subdir('docs/docs/manual')
 
-if not meson.is_subproject()
+if can_add_dist_script
   # Add a ChangeLog file to the distribution directory.
-  # (add_dist_script() is not allowed in a subproject)
   meson.add_dist_script(
     python3.path(), dist_changelog,
     project_source_root,
   )
   # Add build scripts to the distribution directory, and delete .gitignore
-  # files and an empty $MESON_DIST_ROOT/build/ directory.
+  # files and an empty $MESON_PROJECT_DIST_ROOT/build/ directory.
   meson.add_dist_script(
     python3.path(), dist_build_scripts,
     project_source_root,
     'untracked' / 'build_scripts',
   )
-else
-  # This is a subproject.
+endif
+
+if meson.is_subproject()
   sigcxx_dep = declare_dependency(
     dependencies: sigcxx_own_dep,
     variables: {
diff --git a/tools/handle-built-files.py b/tools/handle-built-files.py
index d6957ef..fc1f9b6 100644
--- a/tools/handle-built-files.py
+++ b/tools/handle-built-files.py
@@ -20,9 +20,12 @@ def dist_built_files(is_msvc_files=False):
   # <built_h_cc_dir> <dist_dir> <built_files>...
 
   # <built_h_cc_dir> is an absolute path in the build directory or source directory.
-  # <dist_dir> is a distribution directory, relative to MESON_DIST_ROOT.
+  # <dist_dir> is a distribution directory, relative to MESON_PROJECT_DIST_ROOT.
+
+  # MESON_PROJECT_DIST_ROOT is set only if meson.version() >= 0.58.0.
+  project_dist_root = os.getenv('MESON_PROJECT_DIST_ROOT', os.getenv('MESON_DIST_ROOT'))
   built_h_cc_dir = sys.argv[2]
-  dist_dir_root = os.path.join(os.getenv('MESON_DIST_ROOT'), sys.argv[3])
+  dist_dir_root = os.path.join(project_dist_root, sys.argv[3])
   dist_dir = dist_dir_root
 
   # Distribute .h and .cc files built from .m4 files, or generated MSVC files.
diff --git a/tools/tutorial-custom-cmd.py b/tools/tutorial-custom-cmd.py
index 85b22e7..a99521a 100755
--- a/tools/tutorial-custom-cmd.py
+++ b/tools/tutorial-custom-cmd.py
@@ -132,11 +132,14 @@ def dist_doc():
   #    argv[2]        argv[3]        argv[4]    argv[5]
   # <doc_dist_dir> <doc_build_dir> <xml_file> <pdf_file>
 
-  # <doc_dist_dir> is a distribution directory, relative to MESON_DIST_ROOT.
+  # <doc_dist_dir> is a distribution directory, relative to MESON_PROJECT_DIST_ROOT.
   # <doc_build_dir> is a relative or absolute path in the build directory.
   # <xml_file> is a relative or absolute path in the source directory.
   # <pdf_file> is a relative or absolute path in the build directory.
-  doc_dist_dir = os.path.join(os.getenv('MESON_DIST_ROOT'), sys.argv[2])
+
+  # MESON_PROJECT_DIST_ROOT is set only if meson.version() >= 0.58.0.
+  project_dist_root = os.getenv('MESON_PROJECT_DIST_ROOT', os.getenv('MESON_DIST_ROOT'))
+  doc_dist_dir = os.path.join(project_dist_root, sys.argv[2])
   doc_build_dir = sys.argv[3]
   xml_file = sys.argv[4]
   pdf_file = sys.argv[5]