From e147679d4046f4059a2ebbc9c808d3a4192b644a Mon Sep 17 00:00:00 2001
From: "John W. Parent" <45471568+johnwparent@users.noreply.github.com>
Date: Tue, 22 Oct 2024 12:39:48 -0400
Subject: Libmng: Restore Autotools system (#46994)

* Libmng: Restore Autotools system

CMake, when building its Qt gui, depends on Qt, which in turn, depends on libmng, a CMake based build. To avoid this obvious cyclic dependency, we re-introduce libmng's autotools build into Spack and require when building Qt as a CMake dependency, libmng is built with autotools

* Ensure autotools constraint is limited to non-Windows

* refactor qt-libmng relation from CMake
---
 var/spack/repos/builtin/packages/cmake/package.py  |  6 ++++++
 var/spack/repos/builtin/packages/libmng/package.py | 20 +++++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

(limited to 'var')

diff --git a/var/spack/repos/builtin/packages/cmake/package.py b/var/spack/repos/builtin/packages/cmake/package.py
index 7daade48e7..9b4b760a33 100644
--- a/var/spack/repos/builtin/packages/cmake/package.py
+++ b/var/spack/repos/builtin/packages/cmake/package.py
@@ -162,6 +162,12 @@ class Cmake(Package):
     depends_on("gmake", when="platform=freebsd")
 
     depends_on("qt", when="+qtgui")
+    # Qt depends on libmng, which is a CMake package;
+    # ensure we build using a non CMake build system
+    # when libmng is build as a transitive dependency of CMake
+    for plat in ["linux", "darwin", "freebsd"]:
+        with when(f"platform={plat}"):
+            depends_on("libmng build_system=autotools", when="+qtgui")
 
     # See https://gitlab.kitware.com/cmake/cmake/-/issues/21135
     conflicts(
diff --git a/var/spack/repos/builtin/packages/libmng/package.py b/var/spack/repos/builtin/packages/libmng/package.py
index 3a5f6cb27d..d3b59562f4 100644
--- a/var/spack/repos/builtin/packages/libmng/package.py
+++ b/var/spack/repos/builtin/packages/libmng/package.py
@@ -3,10 +3,13 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
+import spack.build_systems
+import spack.build_systems.autotools
+import spack.build_systems.cmake
 from spack.package import *
 
 
-class Libmng(CMakePackage):
+class Libmng(CMakePackage, AutotoolsPackage):
     """THE reference library for reading, displaying, writing
     and examining Multiple-Image Network Graphics.  MNG is the animation
     extension to the popular PNG image format."""
@@ -26,9 +29,24 @@ class Libmng(CMakePackage):
     depends_on("zlib-api")
     depends_on("lcms")
 
+    build_system("cmake", "autotools", default="cmake")
+
     def patch(self):
         # jpeg requires stdio to be included before its headers.
         filter_file(r"^(\#include \<jpeglib\.h\>)", "#include<stdio.h>\n\\1", "libmng_types.h")
 
+
+class CMakeBuilder(spack.build_systems.cmake.CMakeBuilder):
     def cmake_args(self):
         return ["-DWITH_LCMS2:BOOL=ON", "-DWITH_LCMS1:BOOL=OFF"]
+
+
+class AutotoolsBuilder(spack.build_systems.autotools.AutotoolsBuilder):
+    @run_before("configure")
+    def clean_preconf(self):
+        """Required, otherwise configure will crash as subdirectories have
+        already been configured"""
+        make("distclean")
+
+    def configure_args(self):
+        return ["--with-lcms2", "--without-lcms1"]
-- 
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