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Emit Debug Variables for Errors Bound in Catch Clauses #40372

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Merged
merged 1 commit into from
Dec 3, 2021
Merged

Emit Debug Variables for Errors Bound in Catch Clauses #40372

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9 changes: 9 additions & 0 deletions lib/SILGen/SILGenPattern.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3007,6 +3007,10 @@ void SILGenFunction::emitCatchDispatch(DoCatchStmt *S, ManagedValue exn,
// If we don't have a multi-pattern 'catch', we can emit the
// body inline. Emit the statement here and bail early.
if (clause->getCaseLabelItems().size() == 1) {
// Debug values for catch clause variables must be nested within a scope for
// the catch block to avoid name conflicts.
DebugScope scope(*this, CleanupLocation(clause));

// If we have case body vars, set them up to point at the matching var
// decls.
if (clause->hasCaseBodyVariables()) {
Expand All @@ -3027,6 +3031,11 @@ void SILGenFunction::emitCatchDispatch(DoCatchStmt *S, ManagedValue exn,
// Ok, we found a match. Update the VarLocs for the case block.
auto v = VarLocs[vd];
VarLocs[expected] = v;

// Emit a debug description of the incoming arg, nested within the scope
// for the pattern match.
SILDebugVariable dbgVar(vd->isLet(), /*ArgNo=*/0);
B.emitDebugDescription(vd, v.value, dbgVar);
}
}
}
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39 changes: 35 additions & 4 deletions test/DebugInfo/catch_let.swift
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Expand Up @@ -9,14 +9,45 @@ func throwing() throws -> () {

func use<T>(_ t: T) {}

public func foo() {
// CHECK-LABEL: define {{.*}}explicitBinding{{.*}}
public func explicitBinding() {
do {
try throwing()
}
catch let error {
// CHECK: call void @llvm.dbg.declare(metadata %swift.error** %{{.*}}, metadata ![[ERROR:[0-9]+]],
// CHECK: ![[ERROR]] = !DILocalVariable(name: "error"
// CHECK: call void @llvm.dbg.declare(metadata %swift.error** %{{.*}}, metadata ![[EXPLICIT_ERROR:[0-9]+]],
use(error)
}
}
foo();
explicitBinding()

// CHECK-LABEL: define {{.*}}implicitBinding{{.*}}
public func implicitBinding() {
do {
try throwing()
}
catch {
// CHECK: call void @llvm.dbg.declare(metadata %swift.error** %{{.*}}, metadata ![[IMPLICIT_ERROR:[0-9]+]],
use(error)
}
}
implicitBinding()

// CHECK-LABEL: define {{.*}}multiBinding{{.*}}
public func multiBinding() {
do {
try throwing()
}
catch let error as MyError, let error as MyError {
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I'm curious why multiple/duplicate bindings isn't an error.

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Absolutely agreed https://bugs.swift.org/browse/SR-15548

// CHECK: call void @llvm.dbg.declare(metadata %swift.error** %{{.*}}, metadata ![[MULTI_BINDING_ERROR:[0-9]+]],
// CHECK-NOT: call void @llvm.dbg.declare(metadata %swift.error** %{{.*}}
use(error)
} catch {
use(error)
}
}
multiBinding()

// CHECK: ![[EXPLICIT_ERROR]] = !DILocalVariable(name: "error"
// CHECK: ![[IMPLICIT_ERROR]] = !DILocalVariable(name: "error"
// CHECK: ![[MULTI_BINDING_ERROR]] = !DILocalVariable(name: "error"
1 change: 1 addition & 0 deletions test/SILGen/errors.swift
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Expand Up @@ -108,6 +108,7 @@ func dont_return<T>(_ argument: T) throws -> T {
// Catch HomeworkError.CatAteIt.
// CHECK: [[MATCH]]([[T0:%.*]] : @owned $Cat):
// CHECK-NEXT: [[BORROWED_T0:%.*]] = begin_borrow [lexical] [[T0]]
// CHECK-NEXT: debug_value [[BORROWED_T0]] : $Cat
// CHECK-NEXT: [[T0_COPY:%.*]] = copy_value [[BORROWED_T0]]
// CHECK-NEXT: end_borrow [[BORROWED_T0]]
// CHECK-NEXT: destroy_value [[T0]]
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