[clang] ASTContext: flesh out implementation of getCommonNNS #131964
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This was originally split-off from #130537 |
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@llvm/pr-subscribers-clang Author: Matheus Izvekov (mizvekov) ChangesThis properly implements getCommonNNS, for getting the common NestedNameSpecifier, for which the previous implementation was a bare minimum placeholder. Full diff: https://github.com/llvm/llvm-project/pull/131964.diff 3 Files Affected:
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 0adbc19f40096..e256a382dffd6 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -264,7 +264,9 @@ Improvements to Clang's diagnostics
as function arguments or return value respectively. Note that
:doc:`ThreadSafetyAnalysis` still does not perform alias analysis. The
feature will be default-enabled with ``-Wthread-safety`` in a future release.
-- The ``-Wsign-compare`` warning now treats expressions with bitwise not(~) and minus(-) as signed integers
+- Clang will now do a better job producing common nested names, when producing
+ common types for ternary operator, template argument deduction and multiple return auto deduction.
+- The ``-Wsign-compare`` warning now treats expressions with bitwise not(~) and minus(-) as signed integers
except for the case where the operand is an unsigned integer
and throws warning if they are compared with unsigned integers (##18878).
- The ``-Wunnecessary-virtual-specifier`` warning has been added to warn about
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 7ed5b033d9bd8..8ae938244601b 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -13462,13 +13462,114 @@ static ElaboratedTypeKeyword getCommonTypeKeyword(const T *X, const T *Y) {
: ElaboratedTypeKeyword::None;
}
+static NestedNameSpecifier *getCommonNNS(ASTContext &Ctx,
+ NestedNameSpecifier *X,
+ NestedNameSpecifier *Y, bool IsSame) {
+ if (X == Y)
+ return X;
+
+ NestedNameSpecifier *Canon = Ctx.getCanonicalNestedNameSpecifier(X);
+ if (Canon != Ctx.getCanonicalNestedNameSpecifier(Y)) {
+ assert(!IsSame && "Should be the same NestedNameSpecifier");
+ return nullptr;
+ }
+
+ NestedNameSpecifier *R = nullptr;
+ switch (auto KX = X->getKind(), KY = Y->getKind(); KX) {
+ case NestedNameSpecifier::SpecifierKind::Identifier: {
+ assert(KY == NestedNameSpecifier::SpecifierKind::Identifier);
+ IdentifierInfo *II = X->getAsIdentifier();
+ assert(II == Y->getAsIdentifier());
+ NestedNameSpecifier *P =
+ ::getCommonNNS(Ctx, X->getPrefix(), Y->getPrefix(), /*IsSame=*/true);
+ R = NestedNameSpecifier::Create(Ctx, P, II);
+ break;
+ }
+ case NestedNameSpecifier::SpecifierKind::Namespace:
+ case NestedNameSpecifier::SpecifierKind::NamespaceAlias: {
+ assert(KY == NestedNameSpecifier::SpecifierKind::Namespace ||
+ KY == NestedNameSpecifier::SpecifierKind::NamespaceAlias);
+ NestedNameSpecifier *P = ::getCommonNNS(Ctx, X->getPrefix(), Y->getPrefix(),
+ /*IsSame=*/false);
+ NamespaceAliasDecl *AX = X->getAsNamespaceAlias(),
+ *AY = Y->getAsNamespaceAlias();
+ if (declaresSameEntity(AX, AY)) {
+ R = NestedNameSpecifier::Create(Ctx, P, ::getCommonDeclChecked(AX, AY));
+ break;
+ }
+ NamespaceDecl *NX = AX ? AX->getNamespace() : X->getAsNamespace(),
+ *NY = AY ? AY->getNamespace() : Y->getAsNamespace();
+ R = NestedNameSpecifier::Create(Ctx, P, ::getCommonDeclChecked(NX, NY));
+ break;
+ }
+ case NestedNameSpecifier::SpecifierKind::TypeSpec:
+ case NestedNameSpecifier::SpecifierKind::TypeSpecWithTemplate: {
+ assert(KY == NestedNameSpecifier::SpecifierKind::TypeSpec ||
+ KY == NestedNameSpecifier::SpecifierKind::TypeSpecWithTemplate);
+ bool Template =
+ KX == NestedNameSpecifier::SpecifierKind::TypeSpecWithTemplate &&
+ KY == NestedNameSpecifier::SpecifierKind::TypeSpecWithTemplate;
+
+ const Type *TX = X->getAsType(), *TY = Y->getAsType();
+ if (TX == TY) {
+ NestedNameSpecifier *P =
+ ::getCommonNNS(Ctx, X->getPrefix(), Y->getPrefix(),
+ /*IsSame=*/false);
+ R = NestedNameSpecifier::Create(Ctx, P, Template, TX);
+ break;
+ }
+ // TODO: Try to salvage the original prefix.
+ // If getCommonSugaredType removed any top level sugar, the original prefix
+ // is not applicable anymore.
+ NestedNameSpecifier *P = nullptr;
+ const Type *T = Ctx.getCommonSugaredType(QualType(X->getAsType(), 0),
+ QualType(Y->getAsType(), 0),
+ /*Unqualified=*/true)
+ .getTypePtr();
+ switch (T->getTypeClass()) {
+ case Type::Elaborated: {
+ auto *ET = cast<ElaboratedType>(T);
+ R = NestedNameSpecifier::Create(Ctx, ET->getQualifier(), Template,
+ ET->getNamedType().getTypePtr());
+ break;
+ }
+ case Type::DependentName: {
+ auto *DN = cast<DependentNameType>(T);
+ R = NestedNameSpecifier::Create(Ctx, DN->getQualifier(),
+ DN->getIdentifier());
+ break;
+ }
+ case Type::DependentTemplateSpecialization: {
+ auto *DTST = cast<DependentTemplateSpecializationType>(T);
+ T = Ctx.getDependentTemplateSpecializationType(
+ DTST->getKeyword(), /*NNS=*/nullptr, DTST->getIdentifier(),
+ DTST->template_arguments())
+ .getTypePtr();
+ P = DTST->getQualifier();
+ R = NestedNameSpecifier::Create(Ctx, DTST->getQualifier(), Template, T);
+ break;
+ }
+ default:
+ R = NestedNameSpecifier::Create(Ctx, P, Template, T);
+ break;
+ }
+ break;
+ }
+ case NestedNameSpecifier::SpecifierKind::Global:
+ assert(KY == NestedNameSpecifier::SpecifierKind::Global);
+ return X;
+ case NestedNameSpecifier::SpecifierKind::Super:
+ assert(KY == NestedNameSpecifier::SpecifierKind::Super);
+ return X;
+ }
+ assert(Ctx.getCanonicalNestedNameSpecifier(R) == Canon);
+ return R;
+}
+
template <class T>
-static NestedNameSpecifier *getCommonNNS(ASTContext &Ctx, const T *X,
- const T *Y) {
- // FIXME: Try to keep the common NNS sugar.
- return X->getQualifier() == Y->getQualifier()
- ? X->getQualifier()
- : Ctx.getCanonicalNestedNameSpecifier(X->getQualifier());
+static NestedNameSpecifier *getCommonQualifier(ASTContext &Ctx, const T *X,
+ const T *Y, bool IsSame) {
+ return ::getCommonNNS(Ctx, X->getQualifier(), Y->getQualifier(), IsSame);
}
template <class T>
@@ -13879,8 +13980,9 @@ static QualType getCommonNonSugarTypeNode(ASTContext &Ctx, const Type *X,
*NY = cast<DependentNameType>(Y);
assert(NX->getIdentifier() == NY->getIdentifier());
return Ctx.getDependentNameType(
- getCommonTypeKeyword(NX, NY), getCommonNNS(Ctx, NX, NY),
- NX->getIdentifier(), NX->getCanonicalTypeInternal());
+ getCommonTypeKeyword(NX, NY),
+ getCommonQualifier(Ctx, NX, NY, /*IsSame=*/true), NX->getIdentifier(),
+ NX->getCanonicalTypeInternal());
}
case Type::DependentTemplateSpecialization: {
const auto *TX = cast<DependentTemplateSpecializationType>(X),
@@ -13889,8 +13991,9 @@ static QualType getCommonNonSugarTypeNode(ASTContext &Ctx, const Type *X,
auto As = getCommonTemplateArguments(Ctx, TX->template_arguments(),
TY->template_arguments());
return Ctx.getDependentTemplateSpecializationType(
- getCommonTypeKeyword(TX, TY), getCommonNNS(Ctx, TX, TY),
- TX->getIdentifier(), As);
+ getCommonTypeKeyword(TX, TY),
+ getCommonQualifier(Ctx, TX, TY, /*IsSame=*/true), TX->getIdentifier(),
+ As);
}
case Type::UnaryTransform: {
const auto *TX = cast<UnaryTransformType>(X),
@@ -14047,7 +14150,8 @@ static QualType getCommonSugarTypeNode(ASTContext &Ctx, const Type *X,
case Type::Elaborated: {
const auto *EX = cast<ElaboratedType>(X), *EY = cast<ElaboratedType>(Y);
return Ctx.getElaboratedType(
- ::getCommonTypeKeyword(EX, EY), ::getCommonNNS(Ctx, EX, EY),
+ ::getCommonTypeKeyword(EX, EY),
+ ::getCommonQualifier(Ctx, EX, EY, /*IsSame=*/false),
Ctx.getQualifiedType(Underlying),
::getCommonDecl(EX->getOwnedTagDecl(), EY->getOwnedTagDecl()));
}
diff --git a/clang/test/SemaCXX/sugar-common-types.cpp b/clang/test/SemaCXX/sugar-common-types.cpp
index 39a762127811f..3c4de0e2abd5e 100644
--- a/clang/test/SemaCXX/sugar-common-types.cpp
+++ b/clang/test/SemaCXX/sugar-common-types.cpp
@@ -44,7 +44,7 @@ template <class T> struct S1 {
};
N t10 = 0 ? S1<X1>() : S1<Y1>(); // expected-error {{from 'S1<B1>' (aka 'S1<int>')}}
-N t11 = 0 ? S1<X1>::S2<X2>() : S1<Y1>::S2<Y2>(); // expected-error {{from 'S1<int>::S2<B2>' (aka 'S2<void>')}}
+N t11 = 0 ? S1<X1>::S2<X2>() : S1<Y1>::S2<Y2>(); // expected-error {{from 'S1<B1>::S2<B2>' (aka 'S2<void>')}}
template <class T> using Al = S1<T>;
@@ -88,7 +88,7 @@ N t19 = 0 ? (__underlying_type(EnumsX::X)){} : (__underlying_type(EnumsY::Y)){};
// expected-error@-1 {{rvalue of type 'B1' (aka 'int')}}
N t20 = 0 ? (__underlying_type(EnumsX::X)){} : (__underlying_type(EnumsY::X)){};
-// expected-error@-1 {{rvalue of type '__underlying_type(Enums::X)' (aka 'int')}}
+// expected-error@-1 {{rvalue of type '__underlying_type(EnumsB::X)' (aka 'int')}}
using QX = const SB1 *;
using QY = const ::SB1 *;
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erichkeane
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A few small comments, but comments on the function would be great. Code itself looks fine as best I can tell.
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erichkeane
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This properly implements getCommonNNS, for getting the common NestedNameSpecifier, for which the previous implementation was a bare minimum placeholder.
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This properly implements getCommonNNS, for getting the common NestedNameSpecifier, for which the previous implementation was a bare minimum placeholder.