build(c): set -Og -ggdb and warn about Conda setting -O2

Fixes #1608.

c/cmake_modules/AdbcDefines.cmake

@@ -60,8 +60,8 @@ if(CXX_LINKER_SUPPORTS_VERSION_SCRIPT)
 endif()
 
 # Set common build options
+string(TOLOWER "${CMAKE_BUILD_TYPE}" _lower_build_type)
 if("${ADBC_BUILD_WARNING_LEVEL}" STREQUAL "")
-  string(TOLOWER "${CMAKE_BUILD_TYPE}" _lower_build_type)
   if("${_lower_build_type}" STREQUAL "release")
     set(ADBC_BUILD_WARNING_LEVEL "PRODUCTION")
   else()
@@ -92,6 +92,17 @@ elseif(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang"
       -Werror
       -Wno-unused-parameter)
   set(ADBC_C_CXX_FLAGS_PRODUCTION -Wall)
+
+  string(APPEND C_DEBUG_FLAGS " -Og -ggdb")
+  string(APPEND CXX_DEBUG_FLAGS " -Og -ggdb")
+  string(APPEND C_RELWITHDEBINFO_FLAGS " -Og -ggdb")
+  string(APPEND CXX_RELWITHDEBINFO_FLAGS " -Og -ggdb")
+
+  if("${_lower_build_type}" STREQUAL "debug" AND "${CMAKE_CXX_FLAGS}" MATCHES "-O2")
+    # Activate scripts for Conda compilers set CXXFLAGS etc. with -O2.
+    message(WARNING "This is a debug build, but your CXXFLAGS have -O2. This is common in Conda environments.\nReset your CFLAGS, CPPFLAGS, and CXXFLAGS to -Og for debugging."
+    )
+  endif()
 else()
   message(WARNING "Unknown compiler: ${CMAKE_CXX_COMPILER_ID}")
 endif()