From 6333cc2a12dc72d0cfaaac5ade00e9a1b9d6dbce Mon Sep 17 00:00:00 2001
From: Richard Smith <richard@metafoo.co.uk>
Date: Mon, 9 Mar 2020 17:03:56 -0700
Subject: [PATCH] Revert "PR45083: Mark statement expressions as being
 dependent if they contain"

This reverts commit 2669e41b7b9c1561a01048d5ed0aba3c62432dfc, which was
pushed by mistake.
---
 clang/include/clang/AST/Expr.h             | 10 ++++-
 clang/lib/AST/Expr.cpp                     | 47 ----------------------
 clang/test/SemaTemplate/dependent-expr.cpp | 42 +------------------
 3 files changed, 10 insertions(+), 89 deletions(-)

diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index 75b7a5f6ecd3..7271dbb830a2 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -3959,8 +3959,14 @@ class StmtExpr : public Expr {
   Stmt *SubStmt;
   SourceLocation LParenLoc, RParenLoc;
 public:
-  StmtExpr(CompoundStmt *SubStmt, QualType T,
-           SourceLocation LParen, SourceLocation RParen);
+  // FIXME: Does type-dependence need to be computed differently?
+  // FIXME: Do we need to compute instantiation instantiation-dependence for
+  // statements? (ugh!)
+  StmtExpr(CompoundStmt *substmt, QualType T,
+           SourceLocation lp, SourceLocation rp) :
+    Expr(StmtExprClass, T, VK_RValue, OK_Ordinary,
+         T->isDependentType(), false, false, false),
+    SubStmt(substmt), LParenLoc(lp), RParenLoc(rp) { }
 
   /// Build an empty statement expression.
   explicit StmtExpr(EmptyShell Empty) : Expr(StmtExprClass, Empty) { }
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index feaa9e01f8eb..4eb7a177de00 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -4101,53 +4101,6 @@ void ExtVectorElementExpr::getEncodedElementAccess(
   }
 }
 
-StmtExpr::StmtExpr(CompoundStmt *SubStmt, QualType T, SourceLocation LParen,
-                   SourceLocation RParen)
-    : Expr(StmtExprClass, T, VK_RValue, OK_Ordinary, T->isDependentType(),
-           false, false, false),
-      SubStmt(SubStmt), LParenLoc(LParen), RParenLoc(RParen) {
-  llvm::SmallVector<Stmt*, 16> Queue(1, SubStmt);
-  while (!Queue.empty()) {
-    Stmt *S = Queue.pop_back_val();
-    if (!S)
-      continue;
-
-    // If any subexpression is dependent, the statement expression is dependent
-    // in the same way.
-    if (Expr *E = dyn_cast<Expr>(S)) {
-      addDependence(E->getDependence());
-      continue;
-    }
-
-    // FIXME: Need to properly compute whether DeclStmts contain unexpanded
-    // parameter packs.
-    if (DeclStmt *DS = dyn_cast<DeclStmt>(S)) {
-      for (Decl *D : DS->decls()) {
-        // If any contained declaration is in a dependent context, then it
-        // needs to be instantiated, so the statement expression itself is
-        // instantiation-dependent.
-        //
-        // Note that we don't need to worry about the case where the context is
-        // non-dependent but contains dependent entities here (eg, inside a
-        // variable template or alias template): that can only happen at file
-        // scope, where statement expressions are prohibited.
-        if (D->getLexicalDeclContext()->isDependentContext())
-          addDependence(ExprDependence::Instantiation);
-
-        // If any contained variable declaration has a dependent type, we can't
-        // evaluate that declaration.
-        if (auto *VD = dyn_cast<VarDecl>(D))
-          if (VD->getType()->isDependentType())
-            addDependence(ExprDependence::Value);
-      }
-    }
-
-    // Recurse to substatements.
-    // FIXME: Should we skip the unchosen side of 'if constexpr' if known?
-    Queue.insert(Queue.end(), S->child_begin(), S->child_end());
-  }
-}
-
 ShuffleVectorExpr::ShuffleVectorExpr(const ASTContext &C, ArrayRef<Expr*> args,
                                      QualType Type, SourceLocation BLoc,
                                      SourceLocation RP)
diff --git a/clang/test/SemaTemplate/dependent-expr.cpp b/clang/test/SemaTemplate/dependent-expr.cpp
index 12a99acc21cd..bb1e239c3490 100644
--- a/clang/test/SemaTemplate/dependent-expr.cpp
+++ b/clang/test/SemaTemplate/dependent-expr.cpp
@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++2a %s
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// expected-no-diagnostics
 
 // PR5908
 template <typename Iterator>
@@ -107,42 +108,3 @@ namespace PR18152 {
   };
   template struct A<0>;
 }
-
-template<typename T> void stmt_expr_1() {
-  // GCC doesn't check this: it appears to treat statement-expressions as being
-  // value-dependent if they appear in a dependent context, regardless of their
-  // contents.
-  static_assert( ({ false; }), "" ); // expected-error {{failed}}
-}
-void stmt_expr_2() {
-  static_assert( ({ false; }), "" ); // expected-error {{failed}}
-}
-
-namespace PR45083 {
-  struct A { bool x; };
-
-  template<typename> struct B : A {
-    void f() {
-      const int n = ({ if (x) {} 0; });
-    }
-  };
-
-  template void B<int>::f();
-
-  template<typename> void f() {
-    decltype(({})) x; // expected-error {{incomplete type}}
-  }
-  template void f<int>();
-
-  template<typename> auto g() {
-    auto c = [](auto, int) -> decltype(({})) {};
-    using T = decltype(c(0.0, 0));
-    using T = void;
-    return c(0, 0);
-  }
-  using U = decltype(g<int>()); // expected-note {{previous}}
-  using U = float; // expected-error {{different types ('float' vs 'decltype(g<int>())' (aka 'void'))}}
-
-  void h(auto a, decltype(g<char>())*) {} // expected-note {{previous}}
-  void h(auto a, void*) {} // expected-error {{redefinition}}
-}