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[CSClosure] Fix crash in fallthrough statement checking #59059

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Merged
merged 1 commit into from
May 25, 2022
Merged

[CSClosure] Fix crash in fallthrough statement checking #59059

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19 changes: 16 additions & 3 deletions lib/Sema/CSClosure.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1409,7 +1409,15 @@ class SyntacticElementSolutionApplication
}

auto caseStmt = cast<CaseStmt>(rawCase.get<Stmt *>());
visitCaseStmt(caseStmt);
// Body of the `case` statement can contain a `fallthrough`
// statement that requires both source and destination
// `case` preambles to be type-checked, so bodies of `case`
// statements should be visited after preambles.
visitCaseStmtPreamble(caseStmt);
}

for (auto *caseStmt : switchStmt->getCases()) {
visitCaseStmtBody(caseStmt);

// Check restrictions on '@unknown'.
if (caseStmt->hasUnknownAttr()) {
Expand All @@ -1436,7 +1444,7 @@ class SyntacticElementSolutionApplication
return doStmt;
}

ASTNode visitCaseStmt(CaseStmt *caseStmt) {
void visitCaseStmtPreamble(CaseStmt *caseStmt) {
// Translate the patterns and guard expressions for each case label item.
for (auto &caseItem : caseStmt->getMutableCaseLabelItems()) {
SolutionApplicationTarget caseTarget(&caseItem,
Expand All @@ -1453,11 +1461,16 @@ class SyntacticElementSolutionApplication
solution.getType(prev)->mapTypeOutOfContext());
expected->setInterfaceType(type);
}
}

// Translate the body.
void visitCaseStmtBody(CaseStmt *caseStmt) {
auto *newBody = visit(caseStmt->getBody()).get<Stmt *>();
caseStmt->setBody(cast<BraceStmt>(newBody));
}

ASTNode visitCaseStmt(CaseStmt *caseStmt) {
visitCaseStmtPreamble(caseStmt);
visitCaseStmtBody(caseStmt);
return caseStmt;
}

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20 changes: 20 additions & 0 deletions test/expr/closure/multi_statement.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -404,3 +404,23 @@ func test_type_finder_doesnt_walk_into_inner_closures() {
return x
}
}

// rdar://93796211 (issue#59035) - crash during solution application to fallthrough statement
func test_fallthrough_stmt() {
{
var collector: [Void] = []
for _: Void in [] {
switch (() as Void?, ()) {
case (let a?, let b):
// expected-warning@-1 {{constant 'b' inferred to have type '()', which may be unexpected}}
// expected-note@-2 {{add an explicit type annotation to silence this warning}}
collector.append(a)
fallthrough
case (nil, let b):
// expected-warning@-1 {{constant 'b' inferred to have type '()', which may be unexpected}}
// expected-note@-2 {{add an explicit type annotation to silence this warning}}
collector.append(b)
}
}
}()
}