[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

Author: HighCommander4

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 @@ struct TargetFinder {
       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.

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.