Documentation cmake (#1549)

* Documenting the compiler flags

* Moved some android compiler flags and added documentation on them too.

* Some more restructuring.

Removed unnecessary comments that were self described by the code.
Added some more explanations around certain parts of CMake and especially around compiler flags.

1 files changed, 53 insertions, 7 deletions

diff --git a/cmake/CompilerFlags.cmake b/cmake/CompilerFlags.cmake
index 41fee692..970462c8 100644
--- a/cmake/CompilerFlags.cmake
+++ b/cmake/CompilerFlags.cmake
@@ -1,29 +1,53 @@
 include(AddIfFlagCompiles)
 
+# Makes +/- operations on void pointers be considered an error
+# https://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html
 add_if_flag_compiles(-Werror=pointer-arith CMAKE_C_FLAGS)
+
+# Generates error whenever a function is used before being declared
+# https://gcc.gnu.org/onlinedocs/gcc-4.0.1/gcc/Warning-Options.html
 add_if_flag_compiles(-Werror=implicit-function-declaration CMAKE_C_FLAGS)
-# src/external/jar_xm.h does shady stuff
+
+# Allows some casting of pointers without generating a warning
 add_if_flag_compiles(-fno-strict-aliasing CMAKE_C_FLAGS)
 
+if (ENABLE_MSAN AND ENABLE_ASAN)
+    # MSAN and ASAN both work on memory - ASAN does more things
+    MESSAGE(WARNING "Compiling with both AddressSanitizer and MemorySanitizer is not recommended")
+endif()
+
 if (ENABLE_ASAN)
+    
+    # If enabled it would generate errors/warnings for all kinds of memory errors
+    # (like returning a stack variable by reference)
+    # https://clang.llvm.org/docs/AddressSanitizer.html
+    
     add_if_flag_compiles(-fno-omit-frame-pointer CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
     add_if_flag_compiles(-fsanitize=address CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
+    
 endif()
+
 if (ENABLE_UBSAN)
+    
+    # If enabled this will generate errors for undefined behavior points
+    # (like adding +1 to the maximum int value)
+    # https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html
+    
     add_if_flag_compiles(-fno-omit-frame-pointer CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
     add_if_flag_compiles(-fsanitize=undefined CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
+    
 endif()
+
 if (ENABLE_MSAN)
+    
+    # If enabled this will generate warnings for places where uninitialized memory is used
+    # https://clang.llvm.org/docs/MemorySanitizer.html
+    
     add_if_flag_compiles(-fno-omit-frame-pointer CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
     add_if_flag_compiles(-fsanitize=memory CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
+    
 endif()
 
-if (ENABLE_MSAN AND ENABLE_ASAN)
-    MESSAGE(WARNING "Compiling with both AddressSanitizer and MemorySanitizer is not recommended")
-endif()
-
-add_definitions("-DRAYLIB_CMAKE=1")
-
 if(CMAKE_VERSION VERSION_LESS "3.1")
     if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
         add_if_flag_compiles(-std=gnu99 CMAKE_C_FLAGS)
@@ -31,3 +55,25 @@ if(CMAKE_VERSION VERSION_LESS "3.1")
 else()
     set (CMAKE_C_STANDARD 99)
 endif()
+
+if(${PLATFORM} MATCHES "Android")
+    
+    # If enabled will remove dead code during the linking process
+    # https://gcc.gnu.org/onlinedocs/gnat_ugn/Compilation-options.html
+    add_if_flag_compiles(-ffunction-sections CMAKE_C_FLAGS)
+    
+    # If enabled will generate some exception data (usually disabled for C programs)
+    # https://gcc.gnu.org/onlinedocs/gcc-4.2.4/gcc/Code-Gen-Options.html
+    add_if_flag_compiles(-funwind-tables CMAKE_C_FLAGS)
+    
+    # If enabled adds stack protection guards around functions that allocate memory
+    # https://www.keil.com/support/man/docs/armclang_ref/armclang_ref_cjh1548250046139.htm
+    add_if_flag_compiles(-fstack-protector-strong CMAKE_C_FLAGS)
+    
+    # Marks that the library will not be compiled with an executable stack
+    add_if_flag_compiles(-Wa,--noexecstack CMAKE_C_FLAGS)
+    
+    # Do not expand symbolic links or resolve paths like "/./" or "/../", etc.
+    # https://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html
+    add_if_flag_compiles(-no-canonical-prefixes CMAKE_C_FLAGS)
+endif()