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[clangd] Function return type hints: support lambdas, don't duplicate "->"

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While here, fix an ugliness:
  auto foo()->auto { return 42; }
This (silly) code gains a "-> int" hint. While correct and useful, it renders as
  auto foo()->int->auto { return 42; }
which is confusing enough to do more harm than good I think.

Differential Revision: https://reviews.llvm.org/D120416
This commit is contained in:
Sam McCall 2022-02-23 16:59:19 +01:00
parent a74ff3ac2e
commit 257559ed9a
2 changed files with 30 additions and 9 deletions
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27
clang-tools-extra/clangd/InlayHints.cpp
View file

@ -254,17 +254,30 @@ public:
}
bool VisitFunctionDecl(FunctionDecl *D) {
if (auto *AT = D->getReturnType()->getContainedAutoType()) {
QualType Deduced = AT->getDeducedType();
if (!Deduced.isNull()) {
addTypeHint(D->getFunctionTypeLoc().getRParenLoc(), D->getReturnType(),
/*Prefix=*/"-> ");
}
if (auto *FPT =
llvm::dyn_cast<FunctionProtoType>(D->getType().getTypePtr())) {
if (!FPT->hasTrailingReturn())
addReturnTypeHint(D, D->getFunctionTypeLoc().getRParenLoc());
}
return true;
}
bool VisitLambdaExpr(LambdaExpr *E) {
FunctionDecl *D = E->getCallOperator();
if (!E->hasExplicitResultType())
addReturnTypeHint(D, E->hasExplicitParameters()
? D->getFunctionTypeLoc().getRParenLoc()
: E->getIntroducerRange().getEnd());
return true;
}
void addReturnTypeHint(FunctionDecl *D, SourceLocation Loc) {
auto *AT = D->getReturnType()->getContainedAutoType();
if (!AT || AT->getDeducedType().isNull())
return;
addTypeHint(Loc, D->getReturnType(), /*Prefix=*/"-> ");
}
bool VisitVarDecl(VarDecl *D) {
// Do not show hints for the aggregate in a structured binding,
// but show hints for the individual bindings.

12
clang-tools-extra/clangd/unittests/InlayHintTests.cpp
View file

@ -527,13 +527,18 @@ TEST(TypeHints, Lambda) {
assertTypeHints(R"cpp(
void f() {
int cap = 42;
auto $L[[L]] = [cap, $init[[init]] = 1 + 1](int a) {
auto $L[[L]] = [cap, $init[[init]] = 1 + 1](int a$ret[[)]] {
return a + cap + init;
};
}
)cpp",
ExpectedHint{": (lambda)", "L"},
ExpectedHint{": int", "init"});
ExpectedHint{": int", "init"}, ExpectedHint{"-> int", "ret"});
// Lambda return hint shown even if no param list.
assertTypeHints("auto $L[[x]] = <:$ret[[:>]]{return 42;};",
ExpectedHint{": (lambda)", "L"},
ExpectedHint{"-> int", "ret"});
}
// Structured bindings tests.
@ -616,6 +621,9 @@ TEST(TypeHints, ReturnTypeDeduction) {
// Do not hint `auto` for trailing return type.
auto f3() -> int;
// Do not hint when a trailing return type is specified.
auto f4() -> auto* { return "foo"; }
// `auto` conversion operator
struct A {
operator auto($retConv[[)]] { return 42; }