Fix build without feature.xmlstreamreader

This commit introduces a new feature called vkgen for the tool which
depends on xmlstreamreader.

Note that when features.vkgen is disabled, vulkan.pri will generate
dummy qvulkanfunctions.h and qvulkanfunctions_p.h because buildsystem
needs them.

Task-number: QTBUG-76159
Change-Id: I03d526a0fd76a2d8b531940f37538cead109d9d3
Reviewed-by: Jörg Bornemann <joerg.bornemann@qt.io>

3 files changed, 50 insertions, 37 deletions

diff --git a/src/gui/configure.json b/src/gui/configure.json
index c7bafb8925..764e92a729 100644
--- a/src/gui/configure.json
+++ b/src/gui/configure.json
@@ -1357,9 +1357,14 @@
             "condition": "features.opengl-desktop || features.opengl-dynamic || features.opengles2",
             "output": [ "publicFeature", "feature" ]
         },
+        "vkgen": {
+            "label": "vkgen",
+            "condition": "features.xmlstreamreader",
+            "output": [ "privateFeature" ]
+        },
         "vulkan": {
             "label": "Vulkan",
-            "condition": "libs.vulkan",
+            "condition": "features.vkgen && libs.vulkan",
             "output": [ "publicFeature" ]
         },
         "openvg": {
diff --git a/src/gui/vulkan/vulkan.pri b/src/gui/vulkan/vulkan.pri
index 9bd7391235..5c902e8b82 100644
--- a/src/gui/vulkan/vulkan.pri
+++ b/src/gui/vulkan/vulkan.pri
@@ -17,39 +17,45 @@ qtConfig(vulkan) {
     QMAKE_USE += vulkan/nolink
 }
 
-# Generate qvulkanfunctions.h, qvulkanfunctions_p.h, qvulkanfunctions_p.cpp
-QMAKE_QVKGEN_INPUT = vulkan/vk.xml
-QMAKE_QVKGEN_LICENSE_HEADER = $$QT_SOURCE_TREE/header.LGPL
-qtPrepareTool(QMAKE_QVKGEN, qvkgen)
-
-qvkgen_h.commands = $$QMAKE_QVKGEN ${QMAKE_FILE_IN} $$shell_quote($$QMAKE_QVKGEN_LICENSE_HEADER) ${QMAKE_FILE_OUT_PATH}/${QMAKE_FILE_OUT_BASE}
-qvkgen_h.output = $$OUT_PWD/vulkan/qvulkanfunctions.h
-qvkgen_h.input = QMAKE_QVKGEN_INPUT
-qtConfig(vulkan): \
-    qvkgen_h.variable_out = HEADERS
-else: \
-    qvkgen_h.CONFIG += target_predeps no_link
-QMAKE_EXTRA_COMPILERS += qvkgen_h
-
-qvkgen_ph.commands = $$escape_expand(\\n)
-qvkgen_ph.output = $$OUT_PWD/vulkan/qvulkanfunctions_p.h
-qvkgen_ph.input = QMAKE_QVKGEN_INPUT
-qvkgen_ph.depends += $$OUT_PWD/vulkan/qvulkanfunctions.h
-qtConfig(vulkan): \
-    qvkgen_ph.variable_out = HEADERS
-else: \
-    qvkgen_ph.CONFIG += target_predeps no_link
-QMAKE_EXTRA_COMPILERS += qvkgen_ph
-
-qvkgen_pimpl.commands = $$escape_expand(\\n)
-qvkgen_pimpl.output = $$OUT_PWD/vulkan/qvulkanfunctions_p.cpp
-qvkgen_pimpl.input = QMAKE_QVKGEN_INPUT
-qvkgen_pimpl.depends += $$OUT_PWD/vulkan/qvulkanfunctions_p.h
-qtConfig(vulkan): \
-    qvkgen_pimpl.variable_out = SOURCES
-else: \
-    qvkgen_pimpl.CONFIG += target_predeps no_link
-QMAKE_EXTRA_COMPILERS += qvkgen_pimpl
+qtConfig(vkgen) {
+    # Generate qvulkanfunctions.h, qvulkanfunctions_p.h, qvulkanfunctions_p.cpp
+    QMAKE_QVKGEN_INPUT = vulkan/vk.xml
+    QMAKE_QVKGEN_LICENSE_HEADER = $$QT_SOURCE_TREE/header.LGPL
+    qtPrepareTool(QMAKE_QVKGEN, qvkgen)
+
+    qvkgen_h.commands = $$QMAKE_QVKGEN ${QMAKE_FILE_IN} $$shell_quote($$QMAKE_QVKGEN_LICENSE_HEADER) ${QMAKE_FILE_OUT_PATH}/${QMAKE_FILE_OUT_BASE}
+    qvkgen_h.output = $$OUT_PWD/vulkan/qvulkanfunctions.h
+    qvkgen_h.input = QMAKE_QVKGEN_INPUT
+    qtConfig(vulkan): \
+        qvkgen_h.variable_out = HEADERS
+    else: \
+        qvkgen_h.CONFIG += target_predeps no_link
+    QMAKE_EXTRA_COMPILERS += qvkgen_h
+
+    qvkgen_ph.commands = $$escape_expand(\\n)
+    qvkgen_ph.output = $$OUT_PWD/vulkan/qvulkanfunctions_p.h
+    qvkgen_ph.input = QMAKE_QVKGEN_INPUT
+    qvkgen_ph.depends += $$OUT_PWD/vulkan/qvulkanfunctions.h
+    qtConfig(vulkan): \
+        qvkgen_ph.variable_out = HEADERS
+    else: \
+        qvkgen_ph.CONFIG += target_predeps no_link
+    QMAKE_EXTRA_COMPILERS += qvkgen_ph
+
+    qvkgen_pimpl.commands = $$escape_expand(\\n)
+    qvkgen_pimpl.output = $$OUT_PWD/vulkan/qvulkanfunctions_p.cpp
+    qvkgen_pimpl.input = QMAKE_QVKGEN_INPUT
+    qvkgen_pimpl.depends += $$OUT_PWD/vulkan/qvulkanfunctions_p.h
+    qtConfig(vulkan): \
+        qvkgen_pimpl.variable_out = SOURCES
+    else: \
+        qvkgen_pimpl.CONFIG += target_predeps no_link
+    QMAKE_EXTRA_COMPILERS += qvkgen_pimpl
+} else {
+    # generate dummy files to make qmake happy
+    write_file($$OUT_PWD/vulkan/qvulkanfunctions.h)
+    write_file($$OUT_PWD/vulkan/qvulkanfunctions_p.h)
+}
 
 # Ensure qvulkanfunctions.h gets installed correctly
 targ_headers.CONFIG += no_check_exist
diff --git a/src/src.pro b/src/src.pro
index b1afdd27a5..9ccc1e8f65 100644
--- a/src/src.pro
+++ b/src/src.pro
@@ -214,9 +214,11 @@ qtConfig(gui) {
         SUBDIRS += src_3rdparty_freetype
         src_platformsupport.depends += src_3rdparty_freetype
     }
-    SUBDIRS += src_tools_qvkgen
-    src_gui.depends += src_tools_qvkgen
-    TOOLS += src_tools_qvkgen
+    qtConfig(vkgen) {
+        SUBDIRS += src_tools_qvkgen
+        src_gui.depends += src_tools_qvkgen
+        TOOLS += src_tools_qvkgen
+    }
     SUBDIRS += src_gui src_platformsupport src_platformheaders
     qtConfig(opengl): SUBDIRS += src_openglextensions
     src_plugins.depends += src_gui src_platformsupport src_platformheaders