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[3.0 compat] Don't diagnose @escaping var-arg closures. #5217

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Merged
merged 1 commit into from
Oct 11, 2016
Merged

[3.0 compat] Don't diagnose @escaping var-arg closures. #5217

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10 changes: 9 additions & 1 deletion lib/Sema/TypeCheckType.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2002,8 +2002,16 @@ Type TypeResolver::resolveAttributedType(TypeAttributes &attrs,
// Handle @escaping
if (hasFunctionAttr && ty->is<FunctionType>()) {
if (attrs.has(TAK_escaping)) {
// For compatibility with 3.0, we don't emit an error if it appears on a
// variadic argument list.
//
// FIXME: Version-gate on Swift language version 3, as we don't want its
// presence to confuse users.
bool skipDiagnostic = isVariadicFunctionParam;

// The attribute is meaningless except on parameter types.
if (!isFunctionParam) {
bool shouldDiagnose = !isFunctionParam && !skipDiagnostic;
if (shouldDiagnose) {
auto &SM = TC.Context.SourceMgr;
auto loc = attrs.getLoc(TAK_escaping);
auto attrRange = SourceRange(
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5 changes: 5 additions & 0 deletions test/attr/attr_escaping.swift
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Expand Up @@ -139,6 +139,11 @@ func takesVarargsOfFunctions(fns: () -> ()...) {
}
}

// This is allowed, in order to keep source compat with Swift version 3.0.
//
// FIXME: version-gate on Swift version 3
func takesVarargsOfFunctionsExplicitEscaping(fns: @escaping () -> ()...) {}

func takesNoEscapeFunction(fn: () -> ()) { // expected-note {{parameter 'fn' is implicitly non-escaping}}
takesVarargsOfFunctions(fns: fn) // expected-error {{passing non-escaping parameter 'fn' to function expecting an @escaping closure}}
}
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