Feat: implement #[precond] #[hazard] and #[option] proc-macros

[zjp-CN]

This PR mainly implements safety attribute proc-macros listed in the title

• close Syntax: ::memo doesn't compile due to AST parsing from rustc, even for registered tool #6
• cc Attribute syntax #2

For example, #[precond] will expand to

• #[doc] which is used to generate rustdoc content
• #[Safety::inner(Property, kind = "precond", ...)] a registered tool attribute , used in the rustc driver with kind and Property analyzed

#![feature(register_tool)]
#![register_tool(Safety)]

use safety_tool_lib::safety;

#[safety::precond(
    UnReachable,
    memo = "It's undefined behavior to reach code marked with this intrinsic function."
)]

is expanded to

/// It's undefined behavior to reach code marked with this intrinsic function.
#[Safety::inner(
    UnReachable,
    kind = "precond",
    memo = "It's undefined behavior to reach code marked with this intrinsic function."
)]

More examples

#[safety::precond(
    Init(self.ptr, u8, self.len),
    memo = "The ptr must be initialized first!"
)]
#[safety::precond(
    InBound(self.ptr, u8, self.len),
    memo = "The ptr must be within the length."
)]
#[safety::precond(
    ValidNum(self.len*sizeof(u8), [0,isize::MAX]),
    memo = "Slice length can't exceed isize::MAX due to allocation limit."
)]
#[safety::hazard(
    Alias(self.ptr),
    memo = "Make sure don't alias the ptr."
)]

expanded to

/// The ptr must be initialized first!
#[Safety::inner(
    Init(self.ptr, u8, self.len),
    kind = "precond",
    memo = "The ptr must be initialized first!"
)]
/// The ptr must be within the length.
#[Safety::inner(
    InBound(self.ptr, u8, self.len),
    kind = "precond",
    memo = "The ptr must be within the length."
)]
/// Slice length can't exceed isize::MAX due to allocation limit.
#[Safety::inner(
    ValidNum(self.len*sizeof(u8), [0, isize::MAX]),
    kind = "precond",
    memo = "Slice length can't exceed isize::MAX due to allocation limit."
)]
/// Make sure don't alias the ptr.
#[Safety::inner(
    Alias(self.ptr),
    kind = "hazard",
    memo = "Make sure don't alias the ptr."
)]

Implementation details:

• safety-tool-parser crate is a attribute macro syntax parser, and shared between safety-tool-macro and rustc driver
• safety-tool-macro crate is a proc-macro lib, used to add #[doc] and #[Safety::inner] attributes for the annotated function
• safety-tool-lib crate is mainly for public use, especially for another tool like klint
  • the lib crate will contain the analysis routines

NOTE: the registered tool attribute is changed from safety to Safety.