Make typechecking indexed setters with tuples on the right more consistent

[brianrourkeboll]

Description

Fixes #16987.

• Wrap the value expression in indexed setters in extra parentheses in 3 more cases.

  In the scenarios where assigning an unparenthesized tuple using an indexed setter already works, MakeDelayedSet is actually being called twice — once before TcIndexingThen is called, and once inside of it. For SynExpr.NamedIndexedPropertySet, SynExpr.DotIndexedSet, and, SynExpr.DotNamedIndexedPropertySet, it was not being called twice, because we don't actually want to delay it; the expression does, however, need an extra set of parens in order to receive the same treatment later on as the value expression from SynExpr.Set. Whether double parens should really be needed there is a different question (that I did not investigate).

  Extra parens were already added around the value expr for SynExpr.Set

  fsharp/src/Compiler/Checking/CheckExpressions.fs

  Lines 5822 to 5825 in 6b6cca9

  	// synExpr1 <- synExpr2
  	| SynExpr.Set (synExpr1, synExpr2, mStmt) ->
  	TcNonControlFlowExpr env <| fun env ->
  	TcExprThen cenv overallTy env tpenv false synExpr1 [MakeDelayedSet(synExpr2, mStmt)]

  Extra parens were not added for other indexed setters

  fsharp/src/Compiler/Checking/CheckExpressions.fs

  Lines 5836 to 5839 in 6b6cca9

  	// Type.Items(synExpr1) <- synExpr2
  	| SynExpr.NamedIndexedPropertySet (synLongId, synExpr1, synExpr2, mStmt) ->
  	TcNonControlFlowExpr env <| fun env ->
  	TcExprNamedIndexPropertySet cenv overallTy env tpenv (synLongId, synExpr1, synExpr2, mStmt)

  Extra parens are (also) always added here, which is reached from both of the above paths

  fsharp/src/Compiler/Checking/CheckExpressions.fs

  Lines 6601 to 6606 in 6b6cca9

  	| Some (expr3, mOfLeftOfSet) ->
  	if isIndex then
  	[ DelayedDotLookup([ident(nm, mOfLeftOfSet)], mOfLeftOfSet)
  	DelayedApp(ExprAtomicFlag.Atomic, true, synLeftExprOpt, MakeIndexParam None, mOfLeftOfSet)
  	MakeDelayedSet(expr3, mWholeExpr)
  	yield! delayed ]

  In this PR, I am simply adding the extra parens inline when SynExpr.NamedIndexedPropertySet, SynExpr.DotIndexedSet, and, SynExpr.DotNamedIndexedPropertySet are encountered during typechecking. I could alternatively have updated MakeDelayedSet itself to always wrap in double parens, although that would mean that, in the codepaths where that function is already being called twice, we'd be adding extra parens unnecessarily. While excess parens do not affect typechecking in this case (unlike insufficient parens), it seems undesirable to allocate more nodes than we really need, only to strip them later anyway.

Checklist

• Test cases added.
• Release notes entry updated.

[github-actions]

❗ Release notes required

---

✅ Found changes and release notes in following paths:

Change path	Release notes path	Description
src/Compiler	docs/release-notes/.FSharp.Compiler.Service/8.0.400.md

[psfinaki]

Gathering mental energy for this, hope to review this tomorrow ;)

[psfinaki]

Okay this wasn't that hard to understand in the end 🤦

Thanks for the fix and for the thorough testing, consistency in one of the focus areas for F# these days.