This can be renamed on the next version after 21.08.0. User wanted to test
some patches committed upstream so ended up needing to rebase this patch.

From a9f54d7c37b2b738767d757517466768a9f5a8fe Mon Sep 17 00:00:00 2001
From: Theo Anderson <telans@posteo.de>
Date: Wed, 14 Apr 2021 10:16:11 +1200
Subject: [PATCH] build: respect cflags

[Rebased by: Stefan Radermacher <gentoo@zaister.de>]
Signed-off-by: Theo Anderson <telans@posteo.de>
--- a/cmake/modules/PopplerMacros.cmake
+++ b/cmake/modules/PopplerMacros.cmake
@@ -87,20 +87,15 @@ set(_known_build_types RELWITHDEBINFO;RELEASE;DEBUG;DEBUGFULL;PROFILE)
 # CMake toolchain file). To avoid surprising compilation errors, we emit an
 # error in that case, so that the user can handle the  passed CMAKE_BUILD_TYPE
 # in the compiler flags logic below.
-if (NOT "${_CMAKE_BUILD_TYPE_UPPER}" IN_LIST _known_build_types)
-  message(FATAL_ERROR "Unsupported CMAKE_BUILD_TYPE: ${CMAKE_BUILD_TYPE}")
-endif()
 set(_save_cflags "${CMAKE_C_FLAGS}")
 set(_save_cxxflags "${CMAKE_CXX_FLAGS}")
 
 if(CMAKE_COMPILER_IS_GNUCXX)
-  # set the default compile warnings
   set(_warn "-Wall -Wextra -Wpedantic")
   set(_warn "${_warn} -Wno-unused-parameter")
   set(_warn "${_warn} -Wcast-align")
   set(_warn "${_warn} -Wformat-security")
   set(_warn "${_warn} -Wframe-larger-than=65536")
-  set(_warn "${_warn} -Wlogical-op")
   set(_warn "${_warn} -Wmissing-format-attribute")
   set(_warn "${_warn} -Wnon-virtual-dtor")
   set(_warn "${_warn} -Woverloaded-virtual")
@@ -116,20 +111,6 @@ if(CMAKE_COMPILER_IS_GNUCXX)
 
   set(DEFAULT_COMPILE_WARNINGS "${_warn}")
   set(DEFAULT_COMPILE_WARNINGS_EXTRA "${_warn} ${_warnx}")
-
-  set(CMAKE_CXX_FLAGS                "-fno-exceptions -fno-check-new -fno-common -fno-operator-names -D_DEFAULT_SOURCE")
-  set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g")
-  set(CMAKE_CXX_FLAGS_RELEASE        "-O2 -DNDEBUG")
-  set(CMAKE_CXX_FLAGS_DEBUG          "-g -O2 -fno-reorder-blocks -fno-schedule-insns -fno-inline")
-  set(CMAKE_CXX_FLAGS_DEBUGFULL      "-g3 -fno-inline")
-  set(CMAKE_CXX_FLAGS_PROFILE        "-g3 -fno-inline -ftest-coverage -fprofile-arcs")
-  set(CMAKE_C_FLAGS                  "-std=c99 -D_DEFAULT_SOURCE")
-  set(CMAKE_C_FLAGS_RELWITHDEBINFO   "-O2 -g")
-  set(CMAKE_C_FLAGS_RELEASE          "-O2 -DNDEBUG")
-  set(CMAKE_C_FLAGS_DEBUG            "-g -O2 -fno-reorder-blocks -fno-schedule-insns -fno-inline")
-  set(CMAKE_C_FLAGS_DEBUGFULL        "-g3 -fno-inline")
-  set(CMAKE_C_FLAGS_PROFILE          "-g3 -fno-inline -ftest-coverage -fprofile-arcs")
-
   poppler_check_link_flag("-Wl,--as-needed" GCC_HAS_AS_NEEDED)
   if(GCC_HAS_AS_NEEDED)
     set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--as-needed")
@@ -139,56 +120,8 @@ if(CMAKE_COMPILER_IS_GNUCXX)
   set(_compiler_flags_changed 1)
 endif (CMAKE_COMPILER_IS_GNUCXX)
 
-if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
-# set the default compile warnings
-  set(_warn "-Wall -Wextra -Wpedantic")
-  set(_warn "${_warn} -Wno-unused-parameter")
-  set(_warn "${_warn} -Wcast-align")
-  set(_warn "${_warn} -Wformat-security")
-  set(_warn "${_warn} -Wframe-larger-than=65536")
-  set(_warn "${_warn} -Wmissing-format-attribute")
-  set(_warn "${_warn} -Wnon-virtual-dtor")
-  set(_warn "${_warn} -Woverloaded-virtual")
-  set(_warn "${_warn} -Wmissing-declarations")
-  set(_warn "${_warn} -Wundef")
-  set(_warn "${_warn} -Wzero-as-null-pointer-constant")
-  set(_warn "${_warn} -Wshadow")
-  set(_warn "${_warn} -Wweak-vtables")
-
-  # set extra warnings
-  set(_warnx "${_warnx} -Wconversion")
-
-  set(DEFAULT_COMPILE_WARNINGS "${_warn}")
-  set(DEFAULT_COMPILE_WARNINGS_EXTRA "${_warn} ${_warnx}")
-
-  set(CMAKE_CXX_FLAGS                "-fno-exceptions -fno-check-new -fno-common -D_DEFAULT_SOURCE")
-  set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g")
-  set(CMAKE_CXX_FLAGS_RELEASE        "-O2 -DNDEBUG")
-  # clang does not support -fno-reorder-blocks -fno-schedule-insns, so do not use -O2
-  set(CMAKE_CXX_FLAGS_DEBUG          "-g")
-  set(CMAKE_CXX_FLAGS_DEBUGFULL      "-g3 -fno-inline")
-  set(CMAKE_CXX_FLAGS_PROFILE        "-g3 -fno-inline -ftest-coverage -fprofile-arcs")
-  set(CMAKE_C_FLAGS                  "-std=c99 -D_DEFAULT_SOURCE")
-  set(CMAKE_C_FLAGS_RELWITHDEBINFO   "-O2 -g")
-  set(CMAKE_C_FLAGS_RELEASE          "-O2 -DNDEBUG")
-  # clang does not support -fno-reorder-blocks -fno-schedule-insns, so do not use -O2
-  set(CMAKE_C_FLAGS_DEBUG            "-g")
-  set(CMAKE_C_FLAGS_DEBUGFULL        "-g3 -fno-inline")
-  set(CMAKE_C_FLAGS_PROFILE          "-g3 -fno-inline -ftest-coverage -fprofile-arcs")
-  set(_compiler_flags_changed 1)
-endif()
-
-if(CMAKE_C_COMPILER MATCHES "icc")
-  set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g")
-  set(CMAKE_CXX_FLAGS_RELEASE        "-O2 -DNDEBUG")
-  set(CMAKE_CXX_FLAGS_DEBUG          "-O2 -g -0b0 -noalign")
-  set(CMAKE_CXX_FLAGS_DEBUGFULL      "-g -Ob0 -noalign")
-  set(CMAKE_C_FLAGS_RELWITHDEBINFO   "-O2 -g")
-  set(CMAKE_C_FLAGS_RELEASE          "-O2 -DNDEBUG")
-  set(CMAKE_C_FLAGS_DEBUG            "-O2 -g -Ob0 -noalign")
-  set(CMAKE_C_FLAGS_DEBUGFULL        "-g -Ob0 -noalign")
-  set(_compiler_flags_changed 1)
-endif(CMAKE_C_COMPILER MATCHES "icc")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wnon-virtual-dtor -Woverloaded-virtual")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
 
 if(_compiler_flags_changed)
   # Ensure that the previous CMAKE_{C,CXX}_FLAGS are included in the current configuration flags.
-- 
2.33.0