From 0e523618a17a99647fc13a2be1577b9c887d6d64 Mon Sep 17 00:00:00 2001
From: Alexander Alekhin <alexander.a.alekhin@gmail.com>
Date: Sat, 3 Jul 2021 10:57:18 +0000
Subject: [PATCH] cmake: exclude -pthread from Emscripten default build

---
 cmake/OpenCVCompilerOptions.cmake | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/cmake/OpenCVCompilerOptions.cmake b/cmake/OpenCVCompilerOptions.cmake
index 0a10bfffcf..303d4f451e 100644
--- a/cmake/OpenCVCompilerOptions.cmake
+++ b/cmake/OpenCVCompilerOptions.cmake
@@ -177,7 +177,13 @@ if(CV_GCC OR CV_CLANG)
   endif()
 
   # We need pthread's
-  if(UNIX AND NOT ANDROID AND NOT (APPLE AND CV_CLANG)) # TODO
+  if((UNIX
+          AND NOT ANDROID
+          AND NOT (APPLE AND CV_CLANG)
+          AND NOT EMSCRIPTEN
+      )
+      OR (EMSCRIPTEN AND WITH_PTHREADS_PF)  # https://github.com/opencv/opencv/issues/20285
+  )
     add_extra_compiler_option(-pthread)
   endif()