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FixCode: add a fixit to insert the missing enum element cases in switch statements. (#7759)
This doesn't work on entirely empty switch block because we reject such statement during parsing.
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‎lib/SILOptimizer/Mandatory/DataflowDiagnostics.cpp‎

Lines changed: 86 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -13,6 +13,7 @@
1313
#include "swift/SILOptimizer/PassManager/Passes.h"
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#include "swift/SILOptimizer/PassManager/Transforms.h"
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#include "swift/AST/ASTContext.h"
16+
#include "swift/AST/ASTPrinter.h"
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#include "swift/AST/DiagnosticEngine.h"
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#include "swift/AST/DiagnosticsSIL.h"
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#include "swift/AST/Expr.h"
@@ -21,6 +22,8 @@
2122
#include "swift/SIL/SILLocation.h"
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#include "swift/SIL/SILModule.h"
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#include "swift/SIL/SILVisitor.h"
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#include "swift/Syntax/TokenKinds.h"
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using namespace swift;
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template<typename...T, typename...U>
@@ -57,6 +60,88 @@ static void diagnoseMissingReturn(const UnreachableInst *UI,
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}
5861

5962

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/// If the pattern handles an enum element, remove the enum element from the
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/// given set. If seeing uncertain patterns, e.g. any pattern, return true;
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/// otherwise return false.
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static bool
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removedHandledEnumElements(Pattern *P,
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llvm::DenseSet<EnumElementDecl*> &UnhandledElements) {
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if (auto *EEP = dyn_cast<EnumElementPattern>(P)) {
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UnhandledElements.erase(EEP->getElementDecl());
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} else if (auto *VP = dyn_cast<VarPattern>(P)) {
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return removedHandledEnumElements(VP->getSubPattern(), UnhandledElements);
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} else {
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return true;
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}
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return false;
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};
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static void diagnoseMissingCases(ASTContext &Context,
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const SwitchStmt *SwitchS) {
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SourceLoc EndLoc = SwitchS->getEndLoc();
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StringRef Placeholder = "<#Code#>";
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SmallString<32> Buffer;
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llvm::raw_svector_ostream OS(Buffer);
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auto DefaultDiag = [&]() {
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OS << tok::kw_default << ": " << Placeholder << "\n";
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Context.Diags.diagnose(EndLoc, diag::non_exhaustive_switch).
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fixItInsert(EndLoc, Buffer.str());
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};
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// To find the subject enum decl for this switch statement.
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EnumDecl *SubjectED = nullptr;
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if (auto SubjectTy = SwitchS->getSubjectExpr()->getType()) {
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if (auto *ND = SubjectTy->getAnyNominal()) {
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SubjectED = ND->getAsEnumOrEnumExtensionContext();
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}
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}
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// The switch is not about an enum decl, add "default:" instead.
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if (!SubjectED) {
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DefaultDiag();
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return;
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}
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// Assume enum elements are not handled in the switch statement.
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llvm::DenseSet<EnumElementDecl*> UnhandledElements;
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SubjectED->getAllElements(UnhandledElements);
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for (auto Current : SwitchS->getCases()) {
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// For each handled enum element, remove it from the bucket.
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for (auto Item : Current->getCaseLabelItems()) {
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if (removedHandledEnumElements(Item.getPattern(), UnhandledElements)) {
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DefaultDiag();
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return;
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}
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}
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}
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// No unhandled cases, so we are not sure the exact case to add, fall back to
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// default instead.
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if (UnhandledElements.empty()) {
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DefaultDiag();
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return;
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}
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// Sort the missing elements to a vector because set does not guarantee orders.
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SmallVector<EnumElementDecl*, 4> SortedElements;
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SortedElements.insert(SortedElements.begin(), UnhandledElements.begin(),
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UnhandledElements.end());
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std::sort(SortedElements.begin(),SortedElements.end(),
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[](EnumElementDecl *LHS, EnumElementDecl *RHS) {
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return LHS->getNameStr().compare(RHS->getNameStr()) < 0;
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});
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// Print each enum element name.
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std::for_each(SortedElements.begin(), SortedElements.end(),
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[&](EnumElementDecl *EE) {
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OS << tok::kw_case << " ." << EE->getNameStr() << ": " <<
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Placeholder << "\n";
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});
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Context.Diags.diagnose(EndLoc, diag::non_exhaustive_switch).
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fixItInsert(EndLoc, Buffer.str());
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}
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60145
static void diagnoseUnreachable(const SILInstruction *I,
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ASTContext &Context) {
62147
if (auto *UI = dyn_cast<UnreachableInst>(I)) {
@@ -83,7 +168,7 @@ static void diagnoseUnreachable(const SILInstruction *I,
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84169
// A non-exhaustive switch would also produce an unreachable instruction.
85170
if (L.isASTNode<SwitchStmt>()) {
86-
diagnose(Context, L.getEndSourceLoc(), diag::non_exhaustive_switch);
171+
diagnoseMissingCases(Context, L.getAsASTNode<SwitchStmt>());
87172
return;
88173
}
89174

‎test/FixCode/fixits-switch.swift‎

Lines changed: 65 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,65 @@
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// RUN: not %swift -emit-sil -target %target-triple %s -emit-fixits-path %t.remap -I %S/Inputs
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// RUN: c-arcmt-test %t.remap | arcmt-test -verify-transformed-files %s.result
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enum E1 : Int {
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case e1
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case e2
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case e3
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case e4
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}
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func foo1(_ e : E1) -> Int {
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switch(e) {
13+
case .e1:
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return 1
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}
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}
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func foo2(_ i : Int) -> Int {
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switch i {
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case 1:
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return 1
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}
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}
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func foo3(_ c : Character) -> Character {
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switch c {
27+
case "a":
28+
return "a"
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}
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}
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enum E2 {
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case e1(a: Int, s: Int)
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case e2(a: Int)
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case e3(a: Int)
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}
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func foo4(_ e : E2) -> Int {
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switch e {
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case .e2:
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return 1
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}
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}
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func foo5(_ e : E1) -> Int {
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switch e {
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case _ where e.rawValue > 0:
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return 1
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}
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}
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func foo6(_ e : E2) -> Int {
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switch e {
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case let .e1(x, y):
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return x + y
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}
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}
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func foo7(_ e : E2) -> Int {
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switch e {
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case .e2(1): return 0
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case .e1: return 0
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case .e3: return 0
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}
65+
}

‎test/FixCode/fixits-switch.swift.result‎

Lines changed: 76 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,76 @@
1+
// RUN: not %swift -emit-sil -target %target-triple %s -emit-fixits-path %t.remap -I %S/Inputs
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// RUN: c-arcmt-test %t.remap | arcmt-test -verify-transformed-files %s.result
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enum E1 : Int {
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case e1
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case e2
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case e3
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case e4
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}
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func foo1(_ e : E1) -> Int {
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switch(e) {
13+
case .e1:
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return 1
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case .e2: <#Code#>
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case .e3: <#Code#>
17+
case .e4: <#Code#>
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}
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}
20+
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func foo2(_ i : Int) -> Int {
22+
switch i {
23+
case 1:
24+
return 1
25+
default: <#Code#>
26+
}
27+
}
28+
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func foo3(_ c : Character) -> Character {
30+
switch c {
31+
case "a":
32+
return "a"
33+
default: <#Code#>
34+
}
35+
}
36+
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enum E2 {
38+
case e1(a: Int, s: Int)
39+
case e2(a: Int)
40+
case e3(a: Int)
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}
42+
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func foo4(_ e : E2) -> Int {
44+
switch e {
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case .e2:
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return 1
47+
case .e1: <#Code#>
48+
case .e3: <#Code#>
49+
}
50+
}
51+
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func foo5(_ e : E1) -> Int {
53+
switch e {
54+
case _ where e.rawValue > 0:
55+
return 1
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default: <#Code#>
57+
}
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}
59+
60+
func foo6(_ e : E2) -> Int {
61+
switch e {
62+
case let .e1(x, y):
63+
return x + y
64+
case .e2: <#Code#>
65+
case .e3: <#Code#>
66+
}
67+
}
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69+
func foo7(_ e : E2) -> Int {
70+
switch e {
71+
case .e2(1): return 0
72+
case .e1: return 0
73+
case .e3: return 0
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default: <#Code#>
75+
}
76+
}

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