From cbcd07a4815f546739fb1374a7f24f35e5352e17 Mon Sep 17 00:00:00 2001
From: Nathan Ridge <zeratul976@hotmail.com>
Date: Tue, 21 Jan 2020 16:55:43 -0500
Subject: [PATCH] [clangd] Add C++20 concepts support to TargetFinder

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D73140
---
 clang-tools-extra/clangd/FindTarget.cpp                |  4 ++++
 clang-tools-extra/clangd/unittests/FindTargetTests.cpp | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/clang-tools-extra/clangd/FindTarget.cpp b/clang-tools-extra/clangd/FindTarget.cpp
index 6123ffbb76a..ca0584cbec7 100644
--- a/clang-tools-extra/clangd/FindTarget.cpp
+++ b/clang-tools-extra/clangd/FindTarget.cpp
@@ -17,6 +17,7 @@
 #include "clang/AST/DeclarationName.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
+#include "clang/AST/ExprConcepts.h"
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/NestedNameSpecifier.h"
 #include "clang/AST/PrettyPrinter.h"
@@ -279,6 +280,9 @@ public:
       void VisitCallExpr(const CallExpr *CE) {
         Outer.add(CE->getCalleeDecl(), Flags);
       }
+      void VisitConceptSpecializationExpr(const ConceptSpecializationExpr *E) {
+        Outer.add(E->getNamedConcept(), Flags);
+      }
       void VisitDeclRefExpr(const DeclRefExpr *DRE) {
         const Decl *D = DRE->getDecl();
         // UsingShadowDecl allows us to record the UsingDecl.
diff --git a/clang-tools-extra/clangd/unittests/FindTargetTests.cpp b/clang-tools-extra/clangd/unittests/FindTargetTests.cpp
index 96e488d8a0f..0f450e8dfc2 100644
--- a/clang-tools-extra/clangd/unittests/FindTargetTests.cpp
+++ b/clang-tools-extra/clangd/unittests/FindTargetTests.cpp
@@ -339,6 +339,24 @@ TEST_F(TargetDeclTest, ClassTemplate) {
                {"struct Test", Rel::TemplatePattern});
 }
 
+TEST_F(TargetDeclTest, Concept) {
+  Code = R"cpp(
+    template <typename T>
+    concept Fooable = requires (T t) { t.foo(); };
+
+    template <typename T> requires [[Fooable]]<T>
+    void bar(T t) {
+      t.foo();
+    }
+  )cpp";
+  Flags.push_back("-std=c++2a");
+  EXPECT_DECLS(
+      "ConceptSpecializationExpr",
+      // FIXME: Should we truncate the pretty-printed form of a concept decl
+      // somewhere?
+      {"template <typename T> concept Fooable = requires (T t) { t.foo(); };"});
+}
+
 TEST_F(TargetDeclTest, FunctionTemplate) {
   Code = R"cpp(
     // Implicit specialization.
-- 
2.11.0