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diff --git a/tiff/cmake/CompilerChecks.cmake b/tiff/cmake/CompilerChecks.cmake
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+# Compiler feature checks
+#
+# Copyright © 2015 Open Microscopy Environment / University of Dundee
+# Copyright © 2021 Roger Leigh <rleigh@codelibre.net>
+# Written by Roger Leigh <rleigh@codelibre.net>
+#
+# Permission to use, copy, modify, distribute, and sell this software and
+# its documentation for any purpose is hereby granted without fee, provided
+# that (i) the above copyright notices and this permission notice appear in
+# all copies of the software and related documentation, and (ii) the names of
+# Sam Leffler and Silicon Graphics may not be used in any advertising or
+# publicity relating to the software without the specific, prior written
+# permission of Sam Leffler and Silicon Graphics.
+#
+# THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
+# WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+#
+# IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
+# ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
+# OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+# WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
+# LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+# OF THIS SOFTWARE.
+
+
+include(CheckCCompilerFlag)
+
+
+# These are annoyingly verbose, produce false positives or don't work
+# nicely with all supported compiler versions, so are disabled unless
+# explicitly enabled.
+option(extra-warnings "Enable extra compiler warnings" OFF)
+
+# This will cause the compiler to fail when an error occurs.
+option(fatal-warnings "Compiler warnings are errors" OFF)
+
+# Check if the compiler supports each of the following additional
+# flags, and enable them if supported.  This greatly improves the
+# quality of the build by checking for a number of common problems,
+# some of which are quite serious.
+if(CMAKE_C_COMPILER_ID STREQUAL "GNU" OR
+        CMAKE_C_COMPILER_ID MATCHES "Clang")
+    set(test_flags
+            -Wall
+            -Winline
+            -Wformat-security
+            -Wpointer-arith
+            -Wdisabled-optimization
+            -Wno-unknown-pragmas
+            -fstrict-aliasing)
+    if(extra-warnings)
+        list(APPEND test_flags
+                -pedantic
+                -Wextra
+                -Wformat
+                -Wformat-overflow
+                -Wformat-nonliteral
+                -Wformat-signedness
+                -Wformat-truncation
+                -Wdeclaration-after-statement
+                -Wconversion
+                -Wsign-conversion
+                -Wnull-dereference
+                -Wdouble-promotion
+                -Wmisleading-indentation
+                -Wmissing-include-dirs
+                -Wswitch-default
+                -Wswitch-enum
+                -Wunused-local-typedefs
+                -Wunused-parameter
+                -Wuninitialized
+                -Warith-conversion
+                -Wbool-operation
+                -Wduplicated-branches
+                -Wduplicated-cond
+                -Wshadow
+                -Wunused-macros
+                -Wc99-c11-compat
+                -Wcast-qual
+                -Wcast-align
+                -Wwrite-strings
+                -Wdangling-else
+                -Wsizeof-array-div
+                -Wsizeof-pointer-div
+                -Wsizeof-pointer-memaccess
+                -Wlogical-op
+                -Wlogical-not-parentheses
+                -Wstrict-prototypes
+                -Wmissing-declarations
+                -Wredundant-decls
+                -Wno-int-to-pointer-cast
+                -Wfloat-equal
+                -Wfloat-conversion
+                -Wmissing-prototypes
+                -Wunreachable-code)
+    endif()
+    if(fatal-warnings)
+        list(APPEND test_flags
+                -Werror)
+    endif()
+elseif(CMAKE_C_COMPILER_ID STREQUAL "MSVC")
+    set(test_flags)
+    if(extra-warnings)
+        list(APPEND test_flags
+                /W4)
+    else()
+        list(APPEND test_flags
+                /W3)
+    endif()
+    if (fatal-warnings)
+        list(APPEND test_flags
+                /WX)
+    endif()
+endif()
+
+foreach(flag ${test_flags})
+    string(REGEX REPLACE "[^A-Za-z0-9]" "_" flag_var "${flag}")
+    set(test_c_flag "C_FLAG${flag_var}")
+    CHECK_C_COMPILER_FLAG(${flag} "${test_c_flag}")
+    if (${test_c_flag})
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${flag}")
+    endif (${test_c_flag})
+endforeach(flag ${test_flags})