From ac2fd6524afdbaa42266b2c8c198eac7a7ca0a18 Mon Sep 17 00:00:00 2001
From: makise-homura <akemi_homura@kurisa.ch>
Date: Tue, 18 Aug 2020 21:59:46 +0300
Subject: [PATCH] Support building on e2k (Elbrus) architecture

Signed-off-by: makise-homura <akemi_homura@kurisa.ch>
---
 CMakeLists.txt              | 15 ++++++++++++++-
 ChangeLog.d/e2k-support.txt |  5 +++++
 2 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 ChangeLog.d/e2k-support.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f8df14007..3fb4d364d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -152,6 +152,8 @@ endfunction(link_to_source)
 
 string(REGEX MATCH "Clang" CMAKE_COMPILER_IS_CLANG "${CMAKE_C_COMPILER_ID}")
 
+include(CheckCCompilerFlag)
+
 if(CMAKE_COMPILER_IS_GNU)
     # some warnings we want are not available with old GCC versions
     # note: starting with CMake 2.8 we could use CMAKE_C_COMPILER_VERSION
@@ -168,7 +170,18 @@ if(CMAKE_COMPILER_IS_GNU)
         set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wshadow")
     endif()
     if (GCC_VERSION VERSION_GREATER 5.0)
-        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wformat-signedness")
+        CHECK_C_COMPILER_FLAG("-Wformat-signedness" C_COMPILER_SUPPORTS_WFORMAT_SIGNEDNESS)
+        if(C_COMPILER_SUPPORTS_WFORMAT_SIGNEDNESS)
+            set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wformat-signedness")
+        endif()
+    endif()
+    CHECK_C_COMPILER_FLAG("-Wno-signed-one-bit-field" C_COMPILER_SUPPORTS_WSIGNED_ONE_BIT_FIELD)
+    if(C_COMPILER_SUPPORTS_WSIGNED_ONE_BIT_FIELD)
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-signed-one-bit-field")
+    endif()
+    CHECK_C_COMPILER_FLAG("-Wno-sign-compare" C_COMPILER_SUPPORTS_WSIGN_COMPARE)
+    if(C_COMPILER_SUPPORTS_WSIGN_COMPARE)
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-sign-compare")
     endif()
     set(CMAKE_C_FLAGS_RELEASE     "-O2")
     set(CMAKE_C_FLAGS_DEBUG       "-O0 -g3")
diff --git a/ChangeLog.d/e2k-support.txt b/ChangeLog.d/e2k-support.txt
new file mode 100644
index 000000000..19cc3ad68
--- /dev/null
+++ b/ChangeLog.d/e2k-support.txt
@@ -0,0 +1,5 @@
+Features
+   * Support building on e2k (Elbrus) architecture: correctly enable
+     -Wformat-signedness, and pass -Wno-signed-one-bit-field and
+     -Wno-sign-compare to get rid of excess warnings. Contributed by
+     makise-homura (Igor Molchanov) <akemi_homura@kurisa.ch>.