[libclang] Fix crash in member access code completion with implicit base

If there is an unresolved member access AST node, and the base is
implicit, do not access/use it for generating candidate overloads for
code completion results.

Fixes PR31093.

llvm-svn: 298903

3 files changed, 44 insertions, 12 deletions

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index ea4a33d3f57..cfac3f1dc1d 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -4318,7 +4318,10 @@ void Sema::CodeCompleteCall(Scope *S, Expr *Fn, ArrayRef<Expr *> Args) {
       UME->copyTemplateArgumentsInto(TemplateArgsBuffer);
       TemplateArgs = &TemplateArgsBuffer;
     }
-    SmallVector<Expr *, 12> ArgExprs(1, UME->getBase());
+
+    // Add the base as first argument (use a nullptr if the base is implicit).
+    SmallVector<Expr *, 12> ArgExprs(
+        1, UME->isImplicitAccess() ? nullptr : UME->getBase());
     ArgExprs.append(Args.begin(), Args.end());
     UnresolvedSet<8> Decls;
     Decls.append(UME->decls_begin(), UME->decls_end());
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 82834057ee2..bba8216fa2b 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -6307,30 +6307,45 @@ void Sema::AddFunctionCandidates(const UnresolvedSetImpl &Fns,
   for (UnresolvedSetIterator F = Fns.begin(), E = Fns.end(); F != E; ++F) {
     NamedDecl *D = F.getDecl()->getUnderlyingDecl();
     if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
-      if (isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic())
+      if (isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic()) {
+        QualType ObjectType;
+        Expr::Classification ObjectClassification;
+        if (Expr *E = Args[0]) {
+          // Use the explit base to restrict the lookup:
+          ObjectType = E->getType();
+          ObjectClassification = E->Classify(Context);
+        } // .. else there is an implit base.
         AddMethodCandidate(cast<CXXMethodDecl>(FD), F.getPair(),
-                           cast<CXXMethodDecl>(FD)->getParent(),
-                           Args[0]->getType(), Args[0]->Classify(Context),
-                           Args.slice(1), CandidateSet, SuppressUserConversions,
-                           PartialOverloading);
-      else
+                           cast<CXXMethodDecl>(FD)->getParent(), ObjectType,
+                           ObjectClassification, Args.slice(1), CandidateSet,
+                           SuppressUserConversions, PartialOverloading);
+      } else {
         AddOverloadCandidate(FD, F.getPair(), Args, CandidateSet,
                              SuppressUserConversions, PartialOverloading);
+      }
     } else {
       FunctionTemplateDecl *FunTmpl = cast<FunctionTemplateDecl>(D);
       if (isa<CXXMethodDecl>(FunTmpl->getTemplatedDecl()) &&
-          !cast<CXXMethodDecl>(FunTmpl->getTemplatedDecl())->isStatic())
+          !cast<CXXMethodDecl>(FunTmpl->getTemplatedDecl())->isStatic()) {
+        QualType ObjectType;
+        Expr::Classification ObjectClassification;
+        if (Expr *E = Args[0]) {
+          // Use the explit base to restrict the lookup:
+          ObjectType = E->getType();
+          ObjectClassification = E->Classify(Context);
+        } // .. else there is an implit base.
         AddMethodTemplateCandidate(
             FunTmpl, F.getPair(),
             cast<CXXRecordDecl>(FunTmpl->getDeclContext()),
-            ExplicitTemplateArgs, Args[0]->getType(),
-            Args[0]->Classify(Context), Args.slice(1), CandidateSet,
-            SuppressUserConversions, PartialOverloading);
-      else
+            ExplicitTemplateArgs, ObjectType, ObjectClassification,
+            Args.slice(1), CandidateSet, SuppressUserConversions,
+            PartialOverloading);
+      } else {
         AddTemplateOverloadCandidate(FunTmpl, F.getPair(),
                                      ExplicitTemplateArgs, Args,
                                      CandidateSet, SuppressUserConversions,
                                      PartialOverloading);
+      }
     }
   }
 }
diff --git a/clang/test/CodeCompletion/member-access.cpp b/clang/test/CodeCompletion/member-access.cpp
index 8195f764fbb..66872272ee6 100644
--- a/clang/test/CodeCompletion/member-access.cpp
+++ b/clang/test/CodeCompletion/member-access.cpp
@@ -37,6 +37,17 @@ struct Test1 {
   }
 };
 
+struct Foo {
+  void foo() const;
+  static void foo(bool);
+};
+
+struct Bar {
+  void foo(bool param) {
+    Foo::foo(  );// unresolved member expression with an implicit base
+  }
+};
+
   // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:29:6 %s -o - | FileCheck -check-prefix=CHECK-CC1 %s
   // CHECK-CC1: Base1 : Base1::
   // CHECK-CC1: member1 : [#int#][#Base1::#]member1
@@ -52,3 +63,6 @@ struct Test1 {
 
 // Make sure this doesn't crash
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:36:7 %s -verify
+
+// Make sure this also doesn't crash
+// RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:47:14 %s