[PATCH] D132136: [clang] Perform implicit lvalue-to-rvalue cast with new interpreter

[Timm Bäder via Phabricator via cfe-commits]

tbaeder updated this revision to Diff 457838.
tbaeder added a comment.

Add a unit test.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D132136/new/

https://reviews.llvm.org/D132136

Files:
  clang/lib/AST/ExprConstant.cpp
  clang/test/AST/Interp/literals.cpp
  clang/unittests/AST/EvaluateAsRValueTest.cpp


Index: clang/unittests/AST/EvaluateAsRValueTest.cpp
===================================================================
--- clang/unittests/AST/EvaluateAsRValueTest.cpp
+++ clang/unittests/AST/EvaluateAsRValueTest.cpp
@@ -107,3 +107,50 @@
         Args));
   }
 }
+
+class CheckLValueToRValueConversionVisitor
+    : public clang::RecursiveASTVisitor<CheckLValueToRValueConversionVisitor> {
+public:
+  bool VisitDeclRefExpr(const clang::DeclRefExpr *E) {
+    clang::Expr::EvalResult Result;
+    E->EvaluateAsRValue(Result, E->getDecl()->getASTContext(), true);
+
+    EXPECT_TRUE(Result.Val.hasValue());
+    // Since EvaluateAsRValue does an implicit lvalue-to-rvalue conversion,
+    // the result cannot be a LValue.
+    EXPECT_FALSE(Result.Val.isLValue());
+
+    return true;
+  }
+};
+
+class CheckConversionAction : public clang::ASTFrontendAction {
+public:
+  std::unique_ptr<clang::ASTConsumer>
+  CreateASTConsumer(clang::CompilerInstance &Compiler,
+                    llvm::StringRef FilePath) override {
+    return std::make_unique<Consumer>();
+  }
+
+private:
+  class Consumer : public clang::ASTConsumer {
+  public:
+    ~Consumer() override {}
+
+    void HandleTranslationUnit(clang::ASTContext &Ctx) override {
+      CheckLValueToRValueConversionVisitor Evaluator;
+      Evaluator.TraverseDecl(Ctx.getTranslationUnitDecl());
+    }
+  };
+};
+
+TEST(EvaluateAsRValue, LValueToRValueConversionWorks) {
+  std::string ModesToTest[] = {"", "-fexperimental-new-constant-interpreter"};
+  for (std::string const &Mode : ModesToTest) {
+    std::vector<std::string> Args(1, Mode);
+    ASSERT_TRUE(runToolOnCodeWithArgs(std::make_unique<CheckConversionAction>(),
+                                      "constexpr int a = 20;\n"
+                                      "static_assert(a == 20, \"\");\n",
+                                      Args));
+  }
+}
Index: clang/test/AST/Interp/literals.cpp
===================================================================
--- clang/test/AST/Interp/literals.cpp
+++ clang/test/AST/Interp/literals.cpp
@@ -11,6 +11,7 @@
 static_assert(number == 10, "");
 static_assert(number != 10, ""); // expected-error{{failed}} \
                                  // ref-error{{failed}} \
+                                 // expected-note{{evaluates to}} \
                                  // ref-note{{evaluates to}}
 
 constexpr bool getTrue() { return true; }
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -14934,25 +14934,27 @@
 /// lvalue-to-rvalue cast if it is an lvalue.
 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) {
   assert(!E->isValueDependent());
+
+  if (E->getType().isNull())
+    return false;
+
+  if (!CheckLiteralType(Info, E))
+    return false;
+
   if (Info.EnableNewConstInterp) {
     if (!Info.Ctx.getInterpContext().evaluateAsRValue(Info, E, Result))
       return false;
   } else {
-    if (E->getType().isNull())
-      return false;
-
-    if (!CheckLiteralType(Info, E))
-      return false;
-
     if (!::Evaluate(Result, Info, E))
       return false;
+  }
 
-    if (E->isGLValue()) {
-      LValue LV;
-      LV.setFrom(Info.Ctx, Result);
-      if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
-        return false;
-    }
+  // Implicit lvalue-to-rvalue cast.
+  if (E->isGLValue()) {
+    LValue LV;
+    LV.setFrom(Info.Ctx, Result);
+    if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
+      return false;
   }
 
   // Check this core constant expression is a constant expression.

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