fixes lent tuple codegen error

[ringabout]

ref #25783

This pull request addresses an issue with addressability of tuple elements of type lent or var in Nim, ensuring that expressions involving these types are handled correctly during type changes. The main changes introduce a check to prevent attempting to change the type of tuple elements that are views (var or lent), and a new test is added to verify the correct error is raised when trying to take the address of such elements.

Type system and semantic analysis improvements:

• Added the isViewTarget template in semexprs.nim to check if a type is a view (var or lent), and updated changeType to skip type changes for tuple elements that are views. This prevents invalid addressability operations on these types. [1] [2]

Testing:

• Added a new test tlent_tuple_address.nim to verify that attempting to take the address of tuple elements of type lent correctly produces an "expression has no address" error.

[Copilot]

Pull request overview

This PR addresses a semantic typing issue around tuple constructors when the expected tuple element types are view types (var/lent), which could lead to incorrect typing and downstream failures (notably for (lent T, lent T) scenarios referenced in #24723).

Changes:

• Update changeType to avoid rewriting tuple-constructor element node types when the target element type is var/lent.
• Add a regression test ensuring tuple yields requiring lent elements still correctly error when an element has no address.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
tests/lent/tlent_tuple_address.nim	Adds a regression test for tuple yields with lent elements that should fail due to an unaddressable expression.
compiler/semexprs.nim	Prevents changeType from force-typing tuple elements to var/lent, avoiding incorrect view-typing of non-addressable expressions.

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