[compiler v2] enable warnings on unused private funcs, structs, and constants

[junxzm1990]

Description

This PR

Warning Flag (-W) Propagation

Flow

aptos move compile --Wunused                                                                                                                                                                
         ↓                                                                                                                                                                                  
MovePackageOptions::warnings                                                                                                                                                                
         ↓                                                                                                                                                                                  
BuildOptions::warnings                                                                                                                                                                      
         ↓                                                                                                                                                                                  
move_compiler_v2::Options::warnings                                                                                                                                                         
         ↓                                                                                                                                                                                  
GlobalEnv (set_extension)                                                                                                                                                                   
         ↓                                                                                                                                                                                  
Checker (warning_enabled)                                                                                                                                                                   

Implementation

Layer	File
CLI	crates/aptos/src/common/types.rs
Aptos Tool	crates/aptos/src/move_tool/mod.rs
Package	third_party/move/tools/move-package/src/compilation/compiled_package.rs
Compiler	third_party/move/move-compiler-v2/src/lib.rs
Checker	third_party/move/move-compiler-v2/src/env_pipeline/function_checker.rs

Check logic:

pub fn warning_enabled(&self, name: &str) -> bool {                                                                                                                                         
    self.warnings.iter().any(|w| w == name || w == "all")                                                                                                                                   
}                                                                                                                                                                                           

Backward Compatibility

• Default: warnings = vec![] (empty)
• Activation: Explicit --Wunused or --Wall required
• Guard: All checks wrapped in if options.warning_enabled("unused")
• Impact: Zero breaking changes—existing builds unaffected

Close #18652

How Has This Been Tested?

• New test cases covering both happy paths and edge paths

Type of Change

• New feature
• Bug fix
• Breaking change
• Performance improvement
• Refactoring
• Dependency update
• Documentation update
• Tests

Which Components or Systems Does This Change Impact?

• Validator Node
• Full Node (API, Indexer, etc.)
• Move/Aptos Virtual Machine
• Aptos Framework
• Aptos CLI/SDK
• Developer Infrastructure
• Move Compiler
• Other (specify)

[junxzm1990]

• [compiler v2] enable warnings on unused private funcs, structs, and constants #18661 👈 (View in Graphite)
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.