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[SR-13639][Diag] Don't diagnose local type declarations as unreachable #34493

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Merged
merged 1 commit into from
Nov 2, 2020
Merged

[SR-13639][Diag] Don't diagnose local type declarations as unreachable #34493

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5 changes: 5 additions & 0 deletions lib/SILGen/SILGenStmt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -326,6 +326,11 @@ void StmtEmitter::visitBraceStmt(BraceStmt *S) {
// Ignore all other implicit expressions.
continue;
}
} else if (auto D = ESD.dyn_cast<Decl*>()) {
// Local type declarations are not unreachable because they can appear
// after the declared type has already been used.
if (isa<TypeDecl>(D))
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One more thing I realized: local functions (FuncDecl) need the same treatment, because they can also be forward-referenced. Do you mind adding that in this PR or a follow-up?

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@guitard0g guitard0g Oct 30, 2020 •
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Sure thing. On a related note, while testing I found out forward references in this scenario seem to crash the compiler. That bug may need to be fixed before we can add proper tests for the forward reference scenario.

continue;
}

if (StmtType != UnknownStmtType) {
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4 changes: 2 additions & 2 deletions test/SILGen/local_types.swift
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Expand Up @@ -4,7 +4,7 @@
func function1() {
return

class UnreachableClass {} // expected-warning {{code after 'return' will never be executed}}
class LocalClass {}
}

func function2() {
Expand All @@ -19,4 +19,4 @@ func function2() {

// CHECK-LABEL: sil private [transparent] [ossa] @$s11local_types9function2yyFyycfU_1SL_V1xSivpfi : $@convention(thin) () -> Int

// CHECK-LABEL: sil_vtable UnreachableClass
// CHECK-LABEL: sil_vtable LocalClass
11 changes: 10 additions & 1 deletion test/SILGen/unreachable_code.swift
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@@ -1,4 +1,4 @@
// RUN: %target-swift-emit-sil %s -o /dev/null -verify
// RUN: %target-swift-emit-sil %s -verify | %FileCheck %s

func testUnreachableAfterReturn() -> Int {
var x: Int = 3
Expand Down Expand Up @@ -146,3 +146,12 @@ func testUnreachableCatchClause() {
print("some error")
}
}

func sr13639() -> Int {
return Foo.bar
struct Foo { // no-warning
static var bar = 0
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Can you define a method inside Foo and add a CHECK: line to ensure the method is actually emitted, too?

// CHECK: sil private @$s16unreachable_code7sr13639SiyF3FooL_V7fooFuncyyF : $@convention(method) (Foo) -> ()
func fooFunc() {}
}
}