From c72b7b8e5e530fbd03b704380940f5fa86e5341d Mon Sep 17 00:00:00 2001
From: Joerg Bornemann <joerg.bornemann@qt.io>
Date: Fri, 2 Jul 2021 08:58:55 +0200
Subject: [PATCH] Revert "Make toolchain inspection more robust"

This reverts commit 7c62caa3555d247be569102d8f01b3e7ae362b8a.

Certain toolchain files cannot be read in CMake script mode with CMake
versions >= 3.20.

For example, the vcpkg toolchain file overrides add_executable, and
that fails with CMake 3.20:
CMake Error at D:/dev_tools/vcpkg/scripts/buildsystems/vcpkg.cmake:662 (function):
 Built-in flow control command "add_executable" cannot be overridden.

Pick-to: 6.2
Fixes: QTBUG-93627
Change-Id: Ib6e6352dff50b9684dcf81401d138e27e16292c3
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
---
 cmake/QtAutoDetect.cmake        | 37 ++++-----------------------------
 cmake/QtLoadFilePrintVars.cmake | 15 -------------
 2 files changed, 4 insertions(+), 48 deletions(-)
 delete mode 100644 cmake/QtLoadFilePrintVars.cmake

diff --git a/cmake/QtAutoDetect.cmake b/cmake/QtAutoDetect.cmake
index 6a94515e605..8c5cca0ecf7 100644
--- a/cmake/QtAutoDetect.cmake
+++ b/cmake/QtAutoDetect.cmake
@@ -72,37 +72,6 @@ function(qt_auto_detect_cmake_generator)
     endif()
 endfunction()
 
-# Peek into CMAKE_TOOLCHAIN_FILE before it is actually loaded.
-#
-# Usage:
-#   qt_autodetect_read_toolchain_file(tcf VARIABLES CMAKE_SYSTEM_NAME)
-#   if(tcf_CMAKE_SYSTEM_NAME STREQUAL "Android")
-#      ...we have detected Android
-#   endif()
-#
-function(qt_auto_detect_read_toolchain_file prefix)
-    cmake_parse_arguments(arg "" "" "VARIABLES" ${ARGN})
-    set(script_path "${CMAKE_CURRENT_LIST_DIR}/QtLoadFilePrintVars.cmake")
-    execute_process(
-        COMMAND "${CMAKE_COMMAND}" "-DIN_FILE=${CMAKE_TOOLCHAIN_FILE}"
-                "-DVARIABLES=${arg_VARIABLES}" -P "${script_path}"
-        RESULT_VARIABLE exit_code
-        OUTPUT_VARIABLE output
-        ERROR_VARIABLE ignore)
-    if(NOT exit_code EQUAL 0)
-        message(FATAL_ERROR "Executing CMake script ${script_path} failed with code ${exit_code}.")
-    endif()
-    string(REGEX REPLACE "^.*---QtLoadFilePrintVars---\n" "" output "${output}")
-    string(REPLACE ";" "\;" output "${output}")
-    string(REPLACE "\n" ";" output "${output}")
-    foreach(line IN LISTS output)
-        string(REGEX MATCH "-- ([^ ]+) (.*)" m "${line}")
-        if(CMAKE_MATCH_1 IN_LIST arg_VARIABLES)
-            set(${prefix}_${CMAKE_MATCH_1} "${CMAKE_MATCH_2}" PARENT_SCOPE)
-        endif()
-    endforeach()
-endfunction()
-
 function(qt_auto_detect_android)
     # Auto-detect NDK root
     if(NOT DEFINED ANDROID_NDK_ROOT AND DEFINED ANDROID_SDK_ROOT)
@@ -151,8 +120,10 @@ function(qt_auto_detect_android)
     endif()
 
     if(DEFINED CMAKE_TOOLCHAIN_FILE AND NOT DEFINED QT_AUTODETECT_ANDROID)
-        qt_auto_detect_read_toolchain_file(tcf VARIABLES CMAKE_SYSTEM_NAME)
-        if(tcf_CMAKE_SYSTEM_NAME STREQUAL "Android")
+
+        file(READ ${CMAKE_TOOLCHAIN_FILE} toolchain_file_content OFFSET 0 LIMIT 80)
+        string(FIND "${toolchain_file_content}" "The Android Open Source Project" find_result REVERSE)
+        if (NOT ${find_result} EQUAL -1)
             set(android_detected TRUE)
         else()
             set(android_detected FALSE)
diff --git a/cmake/QtLoadFilePrintVars.cmake b/cmake/QtLoadFilePrintVars.cmake
deleted file mode 100644
index fe0f3ee8d2d..00000000000
--- a/cmake/QtLoadFilePrintVars.cmake
+++ /dev/null
@@ -1,15 +0,0 @@
-# Load a file and print variables and their values
-#
-# IN_FILE: path to a file to be included
-# VARIABLES: list of variables to be printed
-
-cmake_minimum_required(VERSION 3.16)
-include("${IN_FILE}")
-
-# Print a magic comment that the caller must look for
-message(STATUS "---QtLoadFilePrintVars---")
-
-# Print the variables
-foreach(v IN LISTS VARIABLES)
-    message(STATUS "${v} ${${v}}")
-endforeach()