[PATCH] D93314: [clangd] go-to-definition on auto unwraps array/pointer types

[Sam McCall via Phabricator via cfe-commits]

sammccall created this revision.
sammccall added a reviewer: qchateau.
Herald added subscribers: usaxena95, kadircet, arphaman.
sammccall requested review of this revision.
Herald added subscribers: cfe-commits, MaskRay, ilya-biryukov.
Herald added a project: clang.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D93314

Files:
  clang-tools-extra/clangd/XRefs.cpp
  clang-tools-extra/clangd/unittests/XRefsTests.cpp


Index: clang-tools-extra/clangd/unittests/XRefsTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/XRefsTests.cpp
+++ clang-tools-extra/clangd/unittests/XRefsTests.cpp
@@ -657,6 +657,13 @@
         ^auto x = ns1::S1{};
       )cpp",
 
+      R"cpp(// auto unwraps pointers
+        struct [[S]] {};
+        S **const*&y();
+
+        ^auto x = y();
+      )cpp",
+
       R"cpp(// decltype on struct
         namespace ns1 {
         struct [[S1]] {};
Index: clang-tools-extra/clangd/XRefs.cpp
===================================================================
--- clang-tools-extra/clangd/XRefs.cpp
+++ clang-tools-extra/clangd/XRefs.cpp
@@ -34,6 +34,7 @@
 #include "clang/AST/Stmt.h"
 #include "clang/AST/StmtCXX.h"
 #include "clang/AST/Type.h"
+#include "clang/AST/TypeVisitor.h"
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/LangOptions.h"
@@ -463,6 +464,31 @@
   return Result;
 }
 
+// Unwrap a type for the purposes of go-to-definition on auto.
+// e.g. pointer types - there's no definition for Foo*, so show class Foo.
+// We could consider unwrapping unique_ptr<T> too - confusing? slippery slope?
+// We could also move this into targetDecl(), but it's semantically iffy.
+QualType unwrapType(QualType T) {
+  struct OneStepUnwrap : TypeVisitor<OneStepUnwrap, QualType> {
+    QualType VisitType(const Type *T) { return QualType(); }
+    QualType VisitArrayType(const ArrayType *T) { return T->getElementType(); }
+    QualType VisitPointerType(const PointerType *T) {
+      return T->getPointeeType();
+    }
+    QualType VisitReferenceType(const ReferenceType *T) {
+      return T->getPointeeTypeAsWritten();
+    }
+  } Unwrap;
+  if (T.isNull())
+    return T;
+  while (true) {
+    QualType Next = Unwrap.Visit(T.getTypePtr());
+    if (Next.isNull())
+      return T;
+    T = Next;
+  }
+}
+
 std::vector<LocatedSymbol> locateSymbolForType(const ParsedAST &AST,
                                                const QualType &Type) {
   const auto &SM = AST.getSourceManager();
@@ -473,7 +499,7 @@
     return {};
   }
 
-  auto Decls = targetDecl(DynTypedNode::create(Type.getNonReferenceType()),
+  auto Decls = targetDecl(DynTypedNode::create(unwrapType(Type)),
                           DeclRelation::TemplatePattern | DeclRelation::Alias);
   if (Decls.empty())
     return {};



Index: clang-tools-extra/clangd/unittests/XRefsTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/XRefsTests.cpp
+++ clang-tools-extra/clangd/unittests/XRefsTests.cpp
@@ -657,6 +657,13 @@
         ^auto x = ns1::S1{};
       )cpp",
 
+      R"cpp(// auto unwraps pointers
+        struct [[S]] {};
+        S **const*&y();
+
+        ^auto x = y();
+      )cpp",
+
       R"cpp(// decltype on struct
         namespace ns1 {
         struct [[S1]] {};
Index: clang-tools-extra/clangd/XRefs.cpp
===================================================================
--- clang-tools-extra/clangd/XRefs.cpp
+++ clang-tools-extra/clangd/XRefs.cpp
@@ -34,6 +34,7 @@
 #include "clang/AST/Stmt.h"
 #include "clang/AST/StmtCXX.h"
 #include "clang/AST/Type.h"
+#include "clang/AST/TypeVisitor.h"
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/LangOptions.h"
@@ -463,6 +464,31 @@
   return Result;
 }
 
+// Unwrap a type for the purposes of go-to-definition on auto.
+// e.g. pointer types - there's no definition for Foo*, so show class Foo.
+// We could consider unwrapping unique_ptr<T> too - confusing? slippery slope?
+// We could also move this into targetDecl(), but it's semantically iffy.
+QualType unwrapType(QualType T) {
+  struct OneStepUnwrap : TypeVisitor<OneStepUnwrap, QualType> {
+    QualType VisitType(const Type *T) { return QualType(); }
+    QualType VisitArrayType(const ArrayType *T) { return T->getElementType(); }
+    QualType VisitPointerType(const PointerType *T) {
+      return T->getPointeeType();
+    }
+    QualType VisitReferenceType(const ReferenceType *T) {
+      return T->getPointeeTypeAsWritten();
+    }
+  } Unwrap;
+  if (T.isNull())
+    return T;
+  while (true) {
+    QualType Next = Unwrap.Visit(T.getTypePtr());
+    if (Next.isNull())
+      return T;
+    T = Next;
+  }
+}
+
 std::vector<LocatedSymbol> locateSymbolForType(const ParsedAST &AST,
                                                const QualType &Type) {
   const auto &SM = AST.getSourceManager();
@@ -473,7 +499,7 @@
     return {};
   }
 
-  auto Decls = targetDecl(DynTypedNode::create(Type.getNonReferenceType()),
+  auto Decls = targetDecl(DynTypedNode::create(unwrapType(Type)),
                           DeclRelation::TemplatePattern | DeclRelation::Alias);
   if (Decls.empty())
     return {};

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