From b515fa56a3144289023dc9588c5f73283599e4d4 Mon Sep 17 00:00:00 2001
From: Lorn Potter <lorn.potter@gmail.com>
Date: Wed, 24 Aug 2022 17:57:54 +1000
Subject: [PATCH] wasm: add Emscripten version check for apps
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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This will tell developers if they are using the wrong version which may
not build or might cause other issues.

Pick-to: 6.4
Fixes: QTBUG-105922
Change-Id: Ic5c4549d5637182dce380e415f131e33a4da416f
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
---
 cmake/QtPublicWasmToolchainHelpers.cmake | 25 ++++++++++++++++++++++++
 src/corelib/Qt6WasmMacros.cmake          |  2 ++
 2 files changed, 27 insertions(+)

diff --git a/cmake/QtPublicWasmToolchainHelpers.cmake b/cmake/QtPublicWasmToolchainHelpers.cmake
index 949cbe9df21..433b29a9def 100644
--- a/cmake/QtPublicWasmToolchainHelpers.cmake
+++ b/cmake/QtPublicWasmToolchainHelpers.cmake
@@ -72,3 +72,28 @@ function(__qt_internal_show_error_no_emscripten_toolchain_file_found_when_using_
         "or provide a path to a valid emscripten installation via the EMSDK "
         "environment variable.")
 endfunction()
+
+function(__qt_internal_get_qt_build_emsdk_version out_var)
+    if(EXISTS "${QT6_INSTALL_PREFIX}/src/corelib/global/qconfig.h")
+        file(READ "${QT6_INSTALL_PREFIX}/src/corelib/global/qconfig.h" ver)
+    else()
+        file(READ "${QT6_INSTALL_PREFIX}/include/QtCore/qconfig.h" ver)
+    endif()
+    string(REGEX MATCH "#define QT_EMCC_VERSION.\"[0-9]+\\.[0-9]+\\.[0-9]+\"" emOutput ${ver})
+    string(REGEX MATCH "[0-9]+\\.[0-9]+\\.[0-9]+" build_emcc_version "${emOutput}")
+    set(${out_var} "${build_emcc_version}" PARENT_SCOPE)
+endfunction()
+
+function(_qt_test_emscripten_version)
+    __qt_internal_get_emcc_recommended_version(_recommended_emver)
+    __qt_internal_get_emroot_path_suffix_from_emsdk_env(emroot_path)
+    __qt_internal_query_emsdk_version("${emroot_path}" TRUE current_emsdk_ver)
+    __qt_internal_get_qt_build_emsdk_version(qt_build_emcc_version)
+
+    if(NOT "${qt_build_emcc_version}" STREQUAL "${current_emsdk_ver}")
+        message("Qt Wasm built with Emscripten version: ${qt_build_emcc_version}")
+        message("You are using Emscripten version: ${current_emsdk_ver}")
+        message("The recommended version of Emscripten for this Qt is: ${_recommended_emver}")
+        message("This may not work correctly")
+    endif()
+endfunction()
diff --git a/src/corelib/Qt6WasmMacros.cmake b/src/corelib/Qt6WasmMacros.cmake
index c3e9613206d..59f69174dbf 100644
--- a/src/corelib/Qt6WasmMacros.cmake
+++ b/src/corelib/Qt6WasmMacros.cmake
@@ -3,6 +3,8 @@
 
 # Copy in Qt HTML/JS launch files for apps.
 function(_qt_internal_wasm_add_target_helpers target)
+
+    _qt_test_emscripten_version()
     get_target_property(targetType "${target}" TYPE)
     if("${targetType}" STREQUAL "EXECUTABLE")