[PATCH] D62814: [clangd] Treat lambdas as functions when preparing hover response

[Kadir Cetinkaya via Phabricator via cfe-commits]

kadircet updated this revision to Diff 202933.
kadircet marked an inline comment as done.
kadircet added a comment.

- Address comments


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D62814/new/

https://reviews.llvm.org/D62814

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
@@ -22,6 +22,7 @@
 #include "llvm/Support/ScopedPrinter.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <string>
 
 namespace clang {
 namespace clangd {
@@ -765,6 +766,70 @@
              {std::string("bool"), std::string("T"), std::string("false")},
          };
        }},
+      // Pointers to lambdas
+      {R"cpp(
+        void foo() {
+          auto lamb = [](int T, bool B) -> bool { return T && B; };
+          auto *b = &lamb;
+          auto *[[^c]] = &b;
+        }
+        )cpp",
+       [](HoverInfo &HI) {
+         HI.NamespaceScope = "";
+         HI.LocalScope = "foo::";
+         HI.Name = "c";
+         HI.Kind = SymbolKind::Variable;
+         HI.Definition = "auto *c = &b";
+         HI.Type = "<lambda> bool(int, bool)";
+         HI.ReturnType = "bool";
+         HI.Parameters = {
+             {std::string("int"), std::string("T"), llvm::None},
+             {std::string("bool"), std::string("B"), llvm::None},
+         };
+         return HI;
+       }},
+      // Lambda parameter with decltype reference
+      {R"cpp(
+        auto lamb = [](int T, bool B) -> bool { return T && B; };
+        void foo(decltype(lamb)& bar) {
+          [[ba^r]](0, false);
+        }
+        )cpp",
+       [](HoverInfo &HI) {
+         HI.NamespaceScope = "";
+         HI.LocalScope = "foo::";
+         HI.Name = "bar";
+         HI.Kind = SymbolKind::Variable;
+         HI.Definition = "decltype(lamb) &bar";
+         HI.Type = "<lambda> bool(int, bool)";
+         HI.ReturnType = "bool";
+         HI.Parameters = {
+             {std::string("int"), std::string("T"), llvm::None},
+             {std::string("bool"), std::string("B"), llvm::None},
+         };
+         return HI;
+       }},
+      // Lambda parameter with decltype
+      {R"cpp(
+        auto lamb = [](int T, bool B) -> bool { return T && B; };
+        void foo(decltype(lamb) bar) {
+          [[ba^r]](0, false);
+        }
+        )cpp",
+       [](HoverInfo &HI) {
+         HI.NamespaceScope = "";
+         HI.LocalScope = "foo::";
+         HI.Name = "bar";
+         HI.Kind = SymbolKind::Variable;
+         HI.Definition = "decltype(lamb) bar";
+         HI.Type = "<lambda> bool(int, bool)";
+         HI.ReturnType = "bool";
+         HI.Parameters = {
+             {std::string("int"), std::string("T"), llvm::None},
+             {std::string("bool"), std::string("B"), llvm::None},
+         };
+         return HI;
+       }},
       // Lambda variable
       {R"cpp(
         void foo() {
@@ -779,7 +844,12 @@
          HI.Name = "lamb";
          HI.Kind = SymbolKind::Variable;
          HI.Definition = "auto lamb = [&bar](int T, bool B) -> bool {}";
-         HI.Type = std::string("class (lambda)");
+         HI.Type = "<lambda> bool(int, bool)";
+         HI.ReturnType = "bool";
+         HI.Parameters = {
+             {std::string("int"), std::string("T"), llvm::None},
+             {std::string("bool"), std::string("B"), llvm::None},
+         };
          return HI;
        }},
       // Local variable in lambda
Index: clang-tools-extra/clangd/XRefs.cpp
===================================================================
--- clang-tools-extra/clangd/XRefs.cpp
+++ clang-tools-extra/clangd/XRefs.cpp
@@ -19,7 +19,9 @@
 #include "index/SymbolLocation.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclTemplate.h"
+#include "clang/AST/ExprCXX.h"
 #include "clang/AST/PrettyPrinter.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/AST/Type.h"
@@ -620,6 +622,23 @@
                          CharSourceRange::getCharRange(Loc, End));
 }
 
+static const FunctionDecl *getUnderlyingFunction(const Decl *D) {
+  // Extract lambda from variables.
+  if (const VarDecl *VD = llvm::dyn_cast<VarDecl>(D)) {
+    auto QT = VD->getType();
+    if (!QT.isNull()) {
+      while (!QT->getPointeeType().isNull())
+        QT = QT->getPointeeType();
+
+      if (const auto *CD = QT->getAsCXXRecordDecl())
+        return CD->getLambdaCallOperator();
+    }
+  }
+
+  // Non-lambda functions.
+  return D->getAsFunction();
+}
+
 /// Generate a \p Hover object given the declaration \p D.
 static HoverInfo getHoverContents(const Decl *D) {
   HoverInfo HI;
@@ -654,13 +673,15 @@
   }
 
   // Fill in types and params.
-  if (const FunctionDecl *FD = D->getAsFunction()) {
+  if (const FunctionDecl *FD = getUnderlyingFunction(D)) {
     HI.ReturnType.emplace();
     llvm::raw_string_ostream OS(*HI.ReturnType);
     FD->getReturnType().print(OS, Policy);
 
     HI.Type.emplace();
     llvm::raw_string_ostream TypeOS(*HI.Type);
+    if (llvm::isa<VarDecl>(D))
+      TypeOS << "<lambda> ";
     FD->getReturnType().print(TypeOS, Policy);
     TypeOS << '(';
 
@@ -693,8 +714,6 @@
     TypeOS << ')';
     // FIXME: handle variadics.
   } else if (const auto *VD = dyn_cast<ValueDecl>(D)) {
-    // FIXME: Currently lambdas are also handled as ValueDecls, they should be
-    // more similar to functions.
     HI.Type.emplace();
     llvm::raw_string_ostream OS(*HI.Type);
     VD->getType().print(OS, Policy);

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