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[CodeComplete] Match argument labels when completing function arguments #36538

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Mar 26, 2021
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[CodeComplete] Match argument labels when completing function arguments #36538

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96 changes: 85 additions & 11 deletions lib/IDE/ExprContextAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -745,6 +745,79 @@ static bool getPositionInArgs(DeclContext &DC, Expr *Args, Expr *CCExpr,
return false;
}

/// Get index of \p CCExpr in \p Params. Note that the position in \p Params may
/// be different than the position in \p Args if there are defaulted arguments
/// in \p Params which don't occur in \p Args.
///
/// \returns \c true if success, \c false if \p CCExpr is not a part of \p Args.
static bool getPositionInParams(DeclContext &DC, Expr *Args, Expr *CCExpr,
ArrayRef<AnyFunctionType::Param> Params,
unsigned &PosInParams) {
if (isa<ParenExpr>(Args)) {
PosInParams = 0;
return true;
}

auto *tuple = dyn_cast<TupleExpr>(Args);
if (!tuple) {
return false;
}

auto &SM = DC.getASTContext().SourceMgr;
PosInParams = 0;
unsigned PosInArgs = 0;
bool LastParamWasVariadic = false;
// We advance PosInArgs until we find argument that is after the code
// completion token, which is when we stop.
// For each argument, we try to find a matching parameter either by matching
// argument labels, in which case PosInParams may be advanced by more than 1,
// or by advancing PosInParams and PosInArgs both by 1.
for (; PosInArgs < tuple->getNumElements(); ++PosInArgs) {
if (!SM.isBeforeInBuffer(tuple->getElement(PosInArgs)->getEndLoc(),
CCExpr->getStartLoc())) {
// The arg is after the code completion position. Stop.
break;
}

auto ArgName = tuple->getElementName(PosInArgs);
// If the last parameter we matched was variadic, we claim all following
// unlabeled arguments for that variadic parameter -> advance PosInArgs but
// not PosInParams.
if (LastParamWasVariadic && ArgName.empty()) {
continue;
} else {
LastParamWasVariadic = false;
}

// Look for a matching parameter label.
bool FoundLabelMatch = false;
for (unsigned i = PosInParams; i < Params.size(); ++i) {
if (Params[i].getLabel() == ArgName) {
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class C {
  func foo(x: Int..., y: Int, z: Int)  {}
}
func test(c: C) {
  c.foo(x: 10, 20, 30, y: 40, #^HERE^#)
}

When PosInArgs is 1, this loop ends up with ++PosInParams which is incorrect. I think we need some special handling for variadic parameters.

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Good thinking! I added special handling for variadics so that variadic parameters consume all unlabelled arguments following them.

Also added the test case you suggested.

// We have found a label match. Advance the position in the params
// to point to the param after the one with this label.
PosInParams = i + 1;
FoundLabelMatch = true;
if (Params[i].isVariadic()) {
LastParamWasVariadic = true;
}
break;
}
}

if (!FoundLabelMatch) {
// We haven't found a matching argument label. Assume the current one is
// named incorrectly and advance by one.
++PosInParams;
}
}
if (PosInArgs < tuple->getNumElements() && PosInParams < Params.size()) {
// We didn't search until the end, so we found a position in Params. Success
return true;
} else {
return false;
}
}

/// Given an expression and its context, the analyzer tries to figure out the
/// expected type of the expression by analyzing its context.
class ExprContextAnalyzer {
Expand Down Expand Up @@ -791,14 +864,12 @@ class ExprContextAnalyzer {
PossibleCallees.assign(Candidates.begin(), Candidates.end());

// Determine the position of code completion token in call argument.
unsigned Position;
unsigned PositionInArgs;
bool HasName;
if (!getPositionInArgs(*DC, Arg, ParsedExpr, Position, HasName))
if (!getPositionInArgs(*DC, Arg, ParsedExpr, PositionInArgs, HasName))
return false;

// Collect possible types (or labels) at the position.
// FIXME: Take variadic and optional parameters into account. We need to do
// something equivalent to 'constraints::matchCallArguments'
{
bool MayNeedName = !HasName && !E->isImplicit() &&
(isa<CallExpr>(E) | isa<SubscriptExpr>(E) ||
Expand All @@ -811,13 +882,22 @@ class ExprContextAnalyzer {
memberDC = typeAndDecl.Decl->getInnermostDeclContext();

auto Params = typeAndDecl.Type->getParams();
unsigned PositionInParams;
if (!getPositionInParams(*DC, Arg, ParsedExpr, Params,
PositionInParams)) {
// If the argument doesn't have a matching position in the parameters,
// indicate that with optional nullptr param.
if (seenArgs.insert({Identifier(), CanType()}).second)
recordPossibleParam(nullptr, /*isRequired=*/false);
continue;
}
ParameterList *paramList = nullptr;
if (auto VD = typeAndDecl.Decl) {
paramList = getParameterList(VD);
if (paramList && paramList->size() != Params.size())
paramList = nullptr;
}
for (auto Pos = Position; Pos < Params.size(); ++Pos) {
for (auto Pos = PositionInParams; Pos < Params.size(); ++Pos) {
const auto &paramType = Params[Pos];
Type ty = paramType.getPlainType();
if (memberDC && ty->hasTypeParameter())
Expand All @@ -843,12 +923,6 @@ class ExprContextAnalyzer {
if (!canSkip)
break;
}
// If the argument position is out of expeceted number, indicate that
// with optional nullptr param.
if (Position >= Params.size()) {
if (seenArgs.insert({Identifier(), CanType()}).second)
recordPossibleParam(nullptr, /*isRequired=*/false);
}
}
}
return !PossibleTypes.empty() || !PossibleParams.empty();
Expand Down
36 changes: 30 additions & 6 deletions test/IDE/complete_call_arg.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,10 @@

// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=LABEL_IN_SELF_DOT_INIT | %FileCheck %s -check-prefix=LABEL_IN_SELF_DOT_INIT

// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=MISSING_REQUIRED_PARAM | %FileCheck %s -check-prefix=MISSING_REQUIRED_PARAM

// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=NAMED_PARAMETER_WITH_LEADING_VARIADIC | %FileCheck %s -check-prefix=NAMED_PARAMETER_WITH_LEADING_VARIADIC

var i1 = 1
var i2 = 2
var oi1 : Int?
Expand Down Expand Up @@ -700,9 +704,7 @@ func testStaticMemberCall() {
// STATIC_METHOD_SECOND: End completions

let _ = TestStaticMemberCall.create2(1, arg3: 2, #^STATIC_METHOD_SKIPPED^#)
// STATIC_METHOD_SKIPPED: Begin completions, 2 items
// FIXME: 'arg3' shouldn't be suggested.
// STATIC_METHOD_SKIPPED: Pattern/ExprSpecific: {#arg3: Int#}[#Int#];
// STATIC_METHOD_SKIPPED: Begin completions, 1 item
// STATIC_METHOD_SKIPPED: Pattern/ExprSpecific: {#arg4: Int#}[#Int#];
// STATIC_METHOD_SKIPPED: End completions

Expand Down Expand Up @@ -739,9 +741,7 @@ func testImplicitMember() {
// IMPLICIT_MEMBER_SECOND: End completions

let _: TestStaticMemberCall = .create2(1, arg3: 2, #^IMPLICIT_MEMBER_SKIPPED^#)
// IMPLICIT_MEMBER_SKIPPED: Begin completions, 2 items
// FIXME: 'arg3' shouldn't be suggested.
// IMPLICIT_MEMBER_SKIPPED: Pattern/ExprSpecific: {#arg3: Int#}[#Int#];
// IMPLICIT_MEMBER_SKIPPED: Begin completions, 1 item
// IMPLICIT_MEMBER_SKIPPED: Pattern/ExprSpecific: {#arg4: Int#}[#Int#];
// IMPLICIT_MEMBER_SKIPPED: End completions

Expand Down Expand Up @@ -923,3 +923,27 @@ func testLabelsInSelfDotInit() {
}
}
}

func testMissingRequiredParameter() {
class C {
func foo(x: Int, y: Int, z: Int) {}
}
func test(c: C) {
c.foo(y: 1, #^MISSING_REQUIRED_PARAM^#)
// MISSING_REQUIRED_PARAM: Begin completions, 1 item
// MISSING_REQUIRED_PARAM-DAG: Pattern/ExprSpecific: {#z: Int#}[#Int#]
// MISSING_REQUIRED_PARAM: End completions
}
}

func testAfterVariadic() {
class C {
func foo(x: Int..., y: Int, z: Int) {}
}
func test(c: C) {
c.foo(x: 10, 20, 30, y: 40, #^NAMED_PARAMETER_WITH_LEADING_VARIADIC^#)
// NAMED_PARAMETER_WITH_LEADING_VARIADIC: Begin completions, 1 item
// NAMED_PARAMETER_WITH_LEADING_VARIADIC-DAG: Pattern/ExprSpecific: {#z: Int#}[#Int#]
// NAMED_PARAMETER_WITH_LEADING_VARIADIC: End completions
}
}
4 changes: 1 addition & 3 deletions test/IDE/complete_call_as_function.swift
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Expand Up @@ -103,10 +103,8 @@ func testCallAsFunctionOverloaded(fn: Functor) {
//OVERLOADED_PAREN: End completions

fn(h: .left, #^OVERLOADED_ARG2_LABEL^#)
// FIXME: Should only suggest 'v:' (rdar://problem/60346573).
//OVERLOADED_ARG2_LABEL: Begin completions, 2 items
//OVERLOADED_ARG2_LABEL: Begin completions, 1 item
//OVERLOADED_ARG2_LABEL-DAG: Pattern/ExprSpecific: {#v: Functor.Vertical#}[#Functor.Vertical#];
//OVERLOADED_ARG2_LABEL-DAG: Pattern/ExprSpecific: {#h: Functor.Horizontal#}[#Functor.Horizontal#];
//OVERLOADED_ARG2_LABEL: End completions

fn(h: .left, v: .#^OVERLOADED_ARG2_VALUE^#)
Expand Down