29 featcompiler optimisation in tree frontend optnone injection clean diagnostics in compiler wrapper

[SizzleUnrlsd]

1. Frontend OptNone (dedicated architecture)

New module:

•	optnone_action.hpp
•	optnone_action.cpp

Role: an ASTConsumer that adds OptimizeNoneAttr + NoInlineAttr to user functions (i.e., those not coming from system headers).
Executed before codegen (via HandleTopLevelDecl + HandleInlineFunctionDefinition).

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2. Pipeline integration

compiler.cpp
The custom OptNoneAction<...> wraps Clang actions (EmitLLVMOnly, EmitLLVM, etc.).
A helper ensures the module is consumed before the action is destroyed (UAF fix).

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3. Configuration flag

New CLI flag:

•	--ct-optnone / --ct-no-optnone

Added to config:

•	config.hpp
•	config.cpp

CLI documentation:

•	help.cc

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4. Warnings handling and compatibility

Detect conflict --ct-optnone + -disable-O0-optnone → clear warning.
In ToMemory, remove -c and -disable-O0-optnone to avoid “unused” warnings.

Fixed bugs

•	ASAN use-after-free: CodeGenAction destroyed the LLVMContext before the module was used.

Fix via a helper that keeps the action alive during module->print(...).
• Attributes not visible: initially injected too late (HandleTranslationUnit), fixed by acting before codegen.

Final result

•	The --ct-optnone flag forces optnone/noinline on user functions.
•	It works even if the automatic -O0 optnone is disabled.
•	No more useless warnings when compiling in-memory.