[PATCH] D158985: [AST] Fix crash in evaluation of OpaqueExpr in Clangd

[Ilya Biryukov via Phabricator via cfe-commits]

ilya-biryukov created this revision.
ilya-biryukov added a reviewer: kadircet.
Herald added a subscriber: arphaman.
Herald added a project: All.
ilya-biryukov requested review of this revision.
Herald added subscribers: cfe-commits, MaskRay.
Herald added projects: clang, clang-tools-extra.

The code mistakenly returns the value as evaluated whenever the
temporary is allocated, but not yet evaluated.

I could only reproduce in Clangd and could not come up with an example
that would crash the compiler. Clangd runs more evaluations for hover
than the language would allow.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D158985

Files:
  clang-tools-extra/clangd/unittests/HoverTests.cpp
  clang/lib/AST/ExprConstant.cpp


Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -7646,7 +7646,8 @@
   }
 
   bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
-    if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E))
+    if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E);
+        Value && !Value->isAbsent())
       return DerivedSuccess(*Value, E);
 
     const Expr *Source = E->getSourceExpr();
Index: clang-tools-extra/clangd/unittests/HoverTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/HoverTests.cpp
+++ clang-tools-extra/clangd/unittests/HoverTests.cpp
@@ -2954,6 +2954,32 @@
          HI.NamespaceScope = "";
          HI.Value = "0";
        }},
+      // Should not crash.
+      {R"objc(
+        typedef struct MyRect {} MyRect;
+
+        @interface IFace
+        @property(nonatomic) MyRect frame;
+        @end
+
+        MyRect foobar() {
+          MyRect mr;
+          return mr;
+        }
+        void test() {
+          IFace *v;
+          v.frame = [[foo^bar]]();
+        }
+        )objc",
+       [](HoverInfo &HI) {
+         HI.Name = "foobar";
+         HI.Kind = index::SymbolKind::Function;
+         HI.NamespaceScope = "";
+         HI.Definition = "MyRect foobar()";
+         HI.Type = {"MyRect ()", "MyRect ()"};
+         HI.ReturnType = {"MyRect", "MyRect"};
+         HI.Parameters.emplace();
+       }},
       {R"cpp(
          void foo(int * __attribute__(([[non^null]], noescape)) );
          )cpp",


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