Avoid stack overflow in Sequentials pattern

[0101]

Fixes#11667

[vzarytovskii]

nice

[abonie]

Should there be a unit test too?

[0101]

Should there be a unit test too?

Probably. Although testing for stack overflow can be tricky.

[nojaf]

Probably. Although testing for stack overflow can be tricky.

In Fantomas, we had a similar problem once. I've added the following test to reproduce the problem:

[<Test>]let``avoid stack-overflow in long array/list,2485`` ()=letmkStringExpr()=
SynExpr.Const(
SynConst.String((System.Guid.NewGuid().ToString("N"), SynStringKind.Regular, Range.Zero)),
Range.Zero
)letlongArrayExpr:SynExpr =let recmkArray count childExpr =if count =20_000then
childExpr
else
mkArray
(count +1)(SynExpr.Sequential(
DebugPointAtSequential.SuppressNeither,true,
mkStringExpr (),
childExpr,
Range.Zero
))
SynExpr.ArrayOrListComputed(true, mkArray 0(mkStringExpr ()), Range.Zero)letast=
ParsedInput.ImplFile(
ParsedImplFileInput("filename.fsx",true,
QualifiedNameOfFile(Ident("", Range.Zero)),[],[],[ SynModuleOrNamespace([],false,
SynModuleOrNamespaceKind.AnonModule,[ SynModuleDecl.Expr(longArrayExpr, Range.Zero)],
PreXmlDoc.Empty,[],
None,
Range.Zero,{ LeadingKeyword = SynModuleOrNamespaceLeadingKeyword.None })],(false,false),{ ConditionalDirectives =[]
CodeComments =[]},
Set.empty
))let_rootNode= ASTTransformer.mkOak None ast
Assert.Pass()