From a9cc014094eb08c25a248498280a1ee426a1aae9 Mon Sep 17 00:00:00 2001
From: Ryan Burns <rtburns-jpl@users.noreply.github.com>
Date: Tue, 17 Nov 2020 12:25:08 -0800
Subject: [PATCH] Enable -fno-common by default to catch ODR violations

This should prevent ODR-violating code in the future
---
 .cmake/isce2_buildflags.cmake | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/.cmake/isce2_buildflags.cmake b/.cmake/isce2_buildflags.cmake
index 5570353..255a56a 100644
--- a/.cmake/isce2_buildflags.cmake
+++ b/.cmake/isce2_buildflags.cmake
@@ -31,3 +31,19 @@ list(FIND CMAKE_PLATFORM_IMPLICIT_LINK_DIRECTORIES ${abs_libdir} isSystemDir)
 if("${isSystemDir}" STREQUAL "-1")
     list(APPEND CMAKE_INSTALL_RPATH ${abs_libdir})
 endif()
+
+option(ISCE2_STRICT_COMPILATION "Enable strict checks during compilation" ON)
+if(ISCE2_STRICT_COMPILATION)
+
+    # Set -fno-common when supported to catch ODR violations
+    include(CheckCCompilerFlag)
+    check_c_compiler_flag(-fno-common C_FNO_COMMON)
+    if(C_FNO_COMMON)
+        add_compile_options($<$<COMPILE_LANGUAGE:C>:-fno-common>)
+    endif()
+    include(CheckCXXCompilerFlag)
+    check_cxx_compiler_flag(-fno-common CXX_FNO_COMMON)
+    if(CXX_FNO_COMMON)
+        add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-fno-common>)
+    endif()
+endif()