[Sema] Remove completion assert in foldSequence for now

Turns out we can also hit this case for some pattern type-checking
cases. I'll fix those in a follow-up and reinstate the assertion.

Author: hamishknight

lib/Sema/TypeCheckExpr.cpp

@@ -613,15 +613,15 @@ swift::DefaultTypeRequest::evaluate(Evaluator &evaluator,
 }
 
 Expr *TypeChecker::foldSequence(SequenceExpr *expr, DeclContext *dc) {
-  // We may end up running pre-checking multiple times for completion, just use
-  // the folded expression if we've already folded the sequence.
-  // FIXME: We ought to fix completion to not pre-check multiple times, strictly
-  // speaking it isn't idempotent (e.g for things like `markDirectCallee`).
-  if (auto *folded = expr->getFoldedExpr()) {
-    ASSERT(dc->getASTContext().CompletionCallback &&
-           "Attempting to fold sequence twice?");
+  // We may end up running pre-checking multiple times for completion and
+  // pattern type-checking, just use the folded expression if we've already
+  // folded the sequence.
+  // FIXME: We ought to fix these cases to not pre-check multiple times,
+  // strictly speaking it isn't idempotent (e.g for things like
+  // `markDirectCallee`).
+  if (auto *folded = expr->getFoldedExpr())
     return folded;
-  }
+
   // First resolve any unresolved decl references in operator positions.
   for (auto i : indices(expr->getElements())) {
     if (i % 2 == 0)

validation-test/compiler_crashers_2/1f6ae695bebb359b.swift renamed to validation-test/compiler_crashers_2_fixed/1f6ae695bebb359b.swift

@@ -1,3 +1,3 @@
 // {"signature":"makeBinOp(swift::ASTContext&, swift::Expr*, swift::Expr*, swift::Expr*, swift::PrecedenceGroupDecl*, bool)"}
-// RUN: not --crash %target-swift-frontend -typecheck %s
+// RUN: not %target-swift-frontend -typecheck %s
 let a= switch a { case &b as? b