CMake: add support for GNU/Hurd

Add a "HURD" CMake platform specification, so it can be properly
checked in the build system.

Set QT_DEFAULT_MKSPEC to the existing hurd-g++ mkspec.

Hurd supports $ORIGIN in RPATH, so enable it.

Hurd uses X11, so add it to the X11_SUPPORTED list.

Enable few more feature checks that apply to Hurd as well: either
because they are provided by GNU libc itself, or because they are
implemented on Hurd.

Check and set the ELF interpreter, as it is a common functionality of
the GNU toolchain.

Change-Id: Id347033560bbc5a2a4e2c3abb493c948c002b40e
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

6 files changed, 10 insertions, 7 deletions

diff --git a/cmake/QtBuild.cmake b/cmake/QtBuild.cmake
index b06dec60d8..d267f560c1 100644
--- a/cmake/QtBuild.cmake
+++ b/cmake/QtBuild.cmake
@@ -362,6 +362,8 @@ elseif(SOLARIS)
              set(QT_DEFAULT_MKSPEC solaris-cc)
         endif()
     endif()
+elseif(HURD)
+    set(QT_DEFAULT_MKSPEC hurd-g++)
 endif()
 
 if(NOT QT_QMAKE_TARGET_MKSPEC)
diff --git a/cmake/QtPlatformSupport.cmake b/cmake/QtPlatformSupport.cmake
index f39bf0e780..a10e7226eb 100644
--- a/cmake/QtPlatformSupport.cmake
+++ b/cmake/QtPlatformSupport.cmake
@@ -18,6 +18,7 @@ qt_set01(FREEBSD CMAKE_SYSTEM_NAME STREQUAL "FreeBSD") # FIXME: How to identify
 qt_set01(NETBSD CMAKE_SYSTEM_NAME STREQUAL "NetBSD") # FIXME: How to identify this?
 qt_set01(WASM CMAKE_SYSTEM_NAME STREQUAL "Emscripten" OR EMSCRIPTEN)
 qt_set01(SOLARIS CMAKE_SYSTEM_NAME STREQUAL "SunOS")
+qt_set01(HURD CMAKE_SYSTEM_NAME STREQUAL "GNU")
 
 qt_set01(BSD APPLE OR OPENBSD OR FREEBSD OR NETBSD)
 
diff --git a/cmake/QtRpathHelpers.cmake b/cmake/QtRpathHelpers.cmake
index 6e3414b50f..cbe33a6b77 100644
--- a/cmake/QtRpathHelpers.cmake
+++ b/cmake/QtRpathHelpers.cmake
@@ -20,7 +20,7 @@ function(qt_compute_relative_rpath_base rpath install_location out_var)
     # needed in the .prf files, but for CMake we need to prepend them ourselves.
     if(APPLE)
         set(rpath_rel_base "@loader_path")
-    elseif(LINUX OR SOLARIS OR FREEBSD)
+    elseif(LINUX OR SOLARIS OR FREEBSD OR HURD)
         set(rpath_rel_base "$ORIGIN")
     else()
         message(WARNING "No known RPATH_REL_BASE for target platform.")
diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index c1259150ab..be4bc7b2de 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -339,7 +339,7 @@ set_property(TARGET Core APPEND PROPERTY
     PRIVATE_HEADER "${CMAKE_CURRENT_BINARY_DIR}/global/qconfig_p.h")
 
 # Find ELF interpreter and define a macro for that:
-if (LINUX AND NOT CMAKE_CROSSCOMPILING AND BUILD_SHARED_LIBS)
+if ((LINUX OR HURD) AND NOT CMAKE_CROSSCOMPILING AND BUILD_SHARED_LIBS)
     if (NOT DEFINED ELF_INTERPRETER)
         execute_process(COMMAND ${CMAKE_COMMAND} -E env LC_ALL=C readelf -l /bin/ls
                         RESULT_VARIABLE readelf_ok
diff --git a/src/corelib/configure.cmake b/src/corelib/configure.cmake
index 08d1e0d976..71e237ae9c 100644
--- a/src/corelib/configure.cmake
+++ b/src/corelib/configure.cmake
@@ -578,7 +578,7 @@ qt_feature("glib" PUBLIC PRIVATE
 qt_feature_definition("glib" "QT_NO_GLIB" NEGATE VALUE "1")
 qt_feature("glibc" PRIVATE
     LABEL "GNU libc"
-    AUTODETECT LINUX
+    AUTODETECT ( LINUX OR HURD )
     CONDITION TEST_glibc
 )
 qt_feature("icu" PRIVATE
@@ -612,7 +612,7 @@ qt_feature("system-libb2" PRIVATE
 # Currently only used by QTemporaryFile; linkat() exists on Android, but hardlink creation fails due to security rules
 qt_feature("linkat" PRIVATE
     LABEL "linkat()"
-    AUTODETECT LINUX AND NOT ANDROID
+    AUTODETECT ( LINUX AND NOT ANDROID ) OR HURD
     CONDITION TEST_linkat
 )
 qt_feature("std-atomic64" PUBLIC
@@ -669,7 +669,7 @@ qt_feature("qqnx_pps" PRIVATE
 )
 qt_feature("renameat2" PRIVATE
     LABEL "renameat2()"
-    CONDITION LINUX AND TEST_renameat2
+    CONDITION ( LINUX OR HURD ) AND TEST_renameat2
 )
 qt_feature("slog2" PRIVATE
     LABEL "slog2"
@@ -677,7 +677,7 @@ qt_feature("slog2" PRIVATE
 )
 qt_feature("statx" PRIVATE
     LABEL "statx() in libc"
-    CONDITION LINUX AND TEST_statx
+    CONDITION ( LINUX OR HURD ) AND TEST_statx
 )
 qt_feature("syslog" PRIVATE
     LABEL "syslog"
diff --git a/src/gui/configure.cmake b/src/gui/configure.cmake
index f5d26977af..b4625c77b4 100644
--- a/src/gui/configure.cmake
+++ b/src/gui/configure.cmake
@@ -25,7 +25,7 @@ set_property(CACHE INPUT_libpng PROPERTY STRINGS undefined no qt system)
 
 
 #### Libraries
-qt_set01(X11_SUPPORTED LINUX OR HPUX OR FREEBSD OR NETBSD OR OPENBSD OR SOLARIS) # special case
+qt_set01(X11_SUPPORTED LINUX OR HPUX OR FREEBSD OR NETBSD OR OPENBSD OR SOLARIS OR HURD) # special case
 qt_find_package(ATSPI2 PROVIDED_TARGETS PkgConfig::ATSPI2 MODULE_NAME gui QMAKE_LIB atspi)
 qt_find_package(DirectFB PROVIDED_TARGETS PkgConfig::DirectFB MODULE_NAME gui QMAKE_LIB directfb)
 qt_find_package(Libdrm PROVIDED_TARGETS Libdrm::Libdrm MODULE_NAME gui QMAKE_LIB drm)