whisper : enable compiler warnings for src

This commit enables compiler warnings for the src directory. Currently
when the WHISPER_ALL_WARNINGS flag is set to ON is only enables warnings
in ggml, by setting GGML_ALL_WARNINGS to ON. This commit adds the same
compiler flags for whisper's src directory.

The motivation for this is to catch potential bugs and issues early on
in the development process.

Author: danbev

src/CMakeLists.txt

@@ -7,6 +7,26 @@ if (WIN32)
     endif()
 endif()
 
+
+if (WHISPER_ALL_WARNINGS)
+    if (NOT MSVC)
+        list(APPEND WARNING_FLAGS -Wall -Wextra -Wpedantic -Wcast-qual -Wno-unused-function)
+        list(APPEND C_FLAGS       -Wshadow -Wstrict-prototypes -Wpointer-arith -Wmissing-prototypes
+                                  -Werror=implicit-int -Werror=implicit-function-declaration)
+        list(APPEND CXX_FLAGS     -Wmissing-declarations -Wmissing-noreturn)
+
+        list(APPEND C_FLAGS   ${WARNING_FLAGS})
+        list(APPEND CXX_FLAGS ${WARNING_FLAGS})
+
+        add_compile_options("$<$<COMPILE_LANGUAGE:C>:${C_FLAGS};${GF_C_FLAGS}>"
+                            "$<$<COMPILE_LANGUAGE:CXX>:${CXX_FLAGS};${GF_CXX_FLAGS}>")
+    else()
+        # todo : msvc
+        set(C_FLAGS   "")
+        set(CXX_FLAGS "")
+    endif()
+endif()
+
 if (WHISPER_COREML)
     find_library(FOUNDATION_FRAMEWORK Foundation)
     find_library(COREML_FRAMEWORK CoreML)