CMake: add with_expat option

The expat library is already optional. This option allows the user to
explictly not use it even if they have it.

This will be used in an upcoming commit to add a minimal CMake build
job to CI which will test that it is possible to build Graphviz
without any of the optional libraries.

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 41918a06fc018e56c6fa22456c9bb3ecbe11eae7..2b3fa70ce5968a225d1b66213a568c67fd6fd222 100644 (file)
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   libraries: lib/cgraph++ and lib/gvc++. It is experimental, meaning
   that it might have breaking changes also in upcoming patch or minor
   releases (towards #2001)
+- CMake builds now support an `with_expat` option that allows the support for
+  using HTML-like labels through the optional expat library to be explicitly
+  enabled (default) or disabled
 
 ### Changed
 

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4fdffc360488a882f1b01c81989f2d9191b379ea..3c316ac0ae8620fd22bd625bd81a91479e9fc1f3 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,6 +5,7 @@ include(FeatureSummary)
 
 # =============================== Build options ================================
 option(enable_ltdl     "Support on-demand plugin loading" ON)
+option(with_expat      "Support HTML-like labels through expat" ON )
 option(with_digcola    "DIGCOLA features in neato layout engine" ON )
 option(with_ipsepcola  "IPSEPCOLA features in neato layout engine (disabled by default - C++ portability issues)." OFF )
 option(with_ortho      "ORTHO features in neato layout engine." ON )
@@ -81,7 +82,11 @@ endif()
 
 find_package(ANN)
 find_package(Cairo)
-find_package(EXPAT)
+
+if(with_expat)
+  find_package(EXPAT)
+endif()
+
 find_package(GD)
 
 if(enable_ltdl)