From 722a82bc18cb48ad82c68a406649459a948fb5d1 Mon Sep 17 00:00:00 2001
From: Kjell Ahlstedt <kjellahlstedt@gmail.com>
Date: Sun, 22 Aug 2021 19:03:43 +0200
Subject: Require meson >= 0.54.0

---
 .github/workflows/meson-clang-10.yml |  9 +++++----
 .github/workflows/meson-gcc-9.yml    |  9 +++++----
 docs/docs/reference/meson.build      | 14 +++-----------
 meson.build                          |  8 ++------
 4 files changed, 15 insertions(+), 25 deletions(-)

diff --git a/.github/workflows/meson-clang-10.yml b/.github/workflows/meson-clang-10.yml
index af19f31..31274d5 100644
--- a/.github/workflows/meson-clang-10.yml
+++ b/.github/workflows/meson-clang-10.yml
@@ -14,13 +14,14 @@ jobs:
         # Prevent blocking apt install on a question during configuring of tzdata.
         export ENV DEBIAN_FRONTEND=noninteractive
         sudo apt update
-        sudo apt install mm-common clang-10 meson ninja-build python3-setuptools --yes
+        sudo apt install mm-common clang-10 ninja-build python3-setuptools python3-pip --yes
+        # Ubuntu 20.04 contains meson 0.53.2, but libsigc++ requires meson >= 0.54.0.
+        # Install it with pip3 instead of apt.
+        sudo pip3 install "meson>=0.54.0"
         export CXX=clang++-10
         meson -Dwarnings=fatal _build
         cd _build
-        # Meson from 0.54.0 understands "meson compile".
-        # Ubuntu 20.04 uses meson 0.53.2.
-        ninja
+        meson compile
     - name: Test
       run: |
         cd _build
diff --git a/.github/workflows/meson-gcc-9.yml b/.github/workflows/meson-gcc-9.yml
index f472d97..29518a9 100644
--- a/.github/workflows/meson-gcc-9.yml
+++ b/.github/workflows/meson-gcc-9.yml
@@ -14,13 +14,14 @@ jobs:
         # Prevent blocking apt install on a question during configuring of tzdata.
         export ENV DEBIAN_FRONTEND=noninteractive
         sudo apt update
-        sudo apt install mm-common g++-9 meson ninja-build python3-setuptools --yes
+        sudo apt install mm-common g++-9 ninja-build python3-setuptools python3-pip --yes
+        # Ubuntu 20.04 contains meson 0.53.2, but libsigc++ requires meson >= 0.54.0.
+        # Install it with pip3 instead of apt.
+        sudo pip3 install "meson>=0.54.0"
         export CXX=g++-9
         meson -Dwarnings=fatal _build
         cd _build
-        # Meson from 0.54.0 understands "meson compile".
-        # Ubuntu 20.04 uses meson 0.53.2.
-        ninja
+        meson compile
     - name: Test
       run: |
         cd _build
diff --git a/docs/docs/reference/meson.build b/docs/docs/reference/meson.build
index 33aac27..397e975 100644
--- a/docs/docs/reference/meson.build
+++ b/docs/docs/reference/meson.build
@@ -18,17 +18,7 @@ docinstall_flags = []
 foreach module : tag_file_modules
   depmod = dependency(module, required: false)
   if depmod.found()
-    if meson.version().version_compare('>=0.54.0')
-      doxytagfile = depmod.get_variable(pkgconfig: 'doxytagfile', internal: 'doxytagfile', default_value: '')
-      htmlrefpub = depmod.get_variable(pkgconfig: 'htmlrefpub', internal: 'htmlrefpub', default_value: '')
-      htmlrefdir = depmod.get_variable(pkgconfig: 'htmlrefdir', internal: 'htmlrefdir', default_value: '')
-    else
-      # TODO: Remove the possibility to build with meson.version() < 0.54.0
-      # when >= 0.54.0 is available in GitHub's CI (continuous integration).
-      doxytagfile = depmod.get_variable(pkgconfig: 'doxytagfile', default_value: '')
-      htmlrefpub = depmod.get_variable(pkgconfig: 'htmlrefpub', default_value: '')
-      htmlrefdir = depmod.get_variable(pkgconfig: 'htmlrefdir', default_value: '')
-    endif
+    doxytagfile = depmod.get_variable(pkgconfig: 'doxytagfile', internal: 'doxytagfile', default_value: '')
     if doxytagfile != ''
       if depmod.type_name() == 'internal'
         # Subprojects must build their tag files before doxygen is called.
@@ -38,6 +28,8 @@ foreach module : tag_file_modules
           doxygen_tag_targets += subproject(module).get_variable('global_tag_file_target')
         endif
       endif
+      htmlrefpub = depmod.get_variable(pkgconfig: 'htmlrefpub', internal: 'htmlrefpub', default_value: '')
+      htmlrefdir = depmod.get_variable(pkgconfig: 'htmlrefdir', internal: 'htmlrefdir', default_value: '')
       if htmlrefpub == ''
         htmlrefpub = htmlrefdir
       elif htmlrefdir == ''
diff --git a/meson.build b/meson.build
index 281e901..343ccd2 100644
--- a/meson.build
+++ b/meson.build
@@ -7,12 +7,9 @@ project('libsigc++', 'cpp',
     'cpp_std=c++17',
     'warning_level=0',
   ],
-  meson_version: '>= 0.51.0', # required for dep.get_variable()
+  meson_version: '>= 0.54.0', # required for meson.override_dependency()
+                              # and dep.get_variable(internal:)
 )
-#TODO: Require meson_version: '>= 0.54.0' when it's available
-# in GitHub's CI (continuous integration).
-# meson_version() >= 0.54.0 is necessary if sigc++ is a subproject,
-# or if mm-common is a subproject of sigc++.
 
 sigcxx_api_version = '3.0'
 sigcxx_pcname = 'sigc++-' + sigcxx_api_version
@@ -148,7 +145,6 @@ sys.exit(os.path.isfile("@0@"))
 endif
 
 # Check if perl is required and available.
-# Done now, when the doc_reference script is available.
 doc_perl_prop = run_command(
   python3, doc_reference, 'get_script_property',
   '', # MMDOCTOOLDIR is not used
-- 
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