Give integer and float literals a sign

[oli-obk]

Proposal

A lot of situations in the compiler check for unary negation of literals.

I think the only place that should have to handle such things is the overflowing literals lint to detect double negation. Everywhere else we should just have the concept of negative literals.

There is an implementation for this from the HIR on forward: rust-lang/rust#136860

Doing it on the AST has language implications that we will need to think about more, but I think overall it makes things simpler or at least more explicit.

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Process

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• File an issue describing the proposal.
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  • Compiler team members can initiate a check-off via @rfcbot fcp merge on either the MCP or the PR.
• Once an MCP is seconded, the Final Comment Period begins. If no objections are raised after 10 days, the MCP is considered approved.

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[rustbot]

Important

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cc @rust-lang/compiler