Disable ICC compiler warnings

Author: mikkelfj

CMakeLists.txt

@@ -280,9 +280,21 @@ elseif (CMAKE_C_COMPILER_ID STREQUAL "GNU")
         # set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wconversion")
     endif()
 
-elseif (CMAKE_C_COMPILER_ID STREQUAL "Intel")
-    message(STATUS "Setting Intel C compiler options")
+elseif (CMAKE_C_COMPItheREQUAL "Intel")
+    # T(ICC) his applies to the Intel Classic Compiler (ICC) only,
+    # not Intel ICX compiler which appears to behave like clang.
+    # NOTE: the ICC compiler is deprecated by Intel, Godbolt, and the Linux kernel,
+    # and will likely not be supported by future flatcc releases.
+    message(STATUS "Setting Intel C (ICC) compiler options")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c11 -Wall -Wextra")
+    # warning #169: expected a declaration
+    # Fallthrough attribute does not like semicolon.
+    # this is fixed in Intel ICC 2021.5.0, but we only have 2021.4.0 in current CI build.
+    # warning #279: controlling expression is constant
+    # We have these everywhere in flatcc generated code.
+    # warning #188: enumerated type mixed with another type
+    # This is not very noisy, but still annoying, e.g. when zeroing an enum.
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -wd169 -wd279 -wd188")
 elseif (MSVC) # using STREQUAL here conflicts with string interpretation changes in CMake
     message(STATUS "Setting MSVC C compiler options")
     # -DFLATCC_PORTABLE also required, but set earlier