[clang] [clang-repl] Names declared in if conditions and for-init statements are local to the inner context (C++ 3.3.2p4) (PR #84150)

via cfe-commits cfe-commits at lists.llvm.org
Wed Mar 6 03:03:01 PST 2024


Stefan =?utf-8?q?Gränitz?= <stefan.graenitz at gmail.com>,
Stefan =?utf-8?q?Gränitz?= <stefan.graenitz at gmail.com>,
Stefan =?utf-8?q?Gränitz?= <stefan.graenitz at gmail.com>,
Stefan =?utf-8?q?Gränitz?= <stefan.graenitz at gmail.com>,
Stefan =?utf-8?q?Gränitz?= <stefan.graenitz at gmail.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/84150 at github.com>


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Stefan Gränitz (weliveindetail)

<details>
<summary>Changes</summary>

A `TopLevelStmtDecl` must be a `DeclContext` itself to avoid variable definitions to be added to the outer `TranslationUnitDecl` context. Additionally, `ActOnForStmt()` requires a `CompoundScope` when processing a `NullStmt` body.

---
Full diff: https://github.com/llvm/llvm-project/pull/84150.diff


9 Files Affected:

- (modified) clang/include/clang/AST/Decl.h (+10-6) 
- (modified) clang/include/clang/AST/DeclBase.h (+1) 
- (modified) clang/include/clang/Basic/DeclNodes.td (+1-1) 
- (modified) clang/include/clang/Sema/Sema.h (+2-1) 
- (modified) clang/lib/AST/Decl.cpp (+8-3) 
- (modified) clang/lib/AST/DeclBase.cpp (+1) 
- (modified) clang/lib/Parse/ParseDecl.cpp (+16-8) 
- (modified) clang/lib/Sema/SemaDecl.cpp (+13-3) 
- (modified) clang/test/Interpreter/execute-stmts.cpp (+13-1) 


``````````diff
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index 61117cc5ce71f9..a5879591f4c659 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -4419,7 +4419,7 @@ class FileScopeAsmDecl : public Decl {
 ///
 /// \note This is used in libInterpreter, clang -cc1 -fincremental-extensions
 /// and in tools such as clang-repl.
-class TopLevelStmtDecl : public Decl {
+class TopLevelStmtDecl : public Decl, public DeclContext {
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
 
@@ -4427,7 +4427,7 @@ class TopLevelStmtDecl : public Decl {
   bool IsSemiMissing = false;
 
   TopLevelStmtDecl(DeclContext *DC, SourceLocation L, Stmt *S)
-      : Decl(TopLevelStmt, DC, L), Statement(S) {}
+      : Decl(TopLevelStmt, DC, L), DeclContext(TopLevelStmt), Statement(S) {}
 
   virtual void anchor();
 
@@ -4438,15 +4438,19 @@ class TopLevelStmtDecl : public Decl {
   SourceRange getSourceRange() const override LLVM_READONLY;
   Stmt *getStmt() { return Statement; }
   const Stmt *getStmt() const { return Statement; }
-  void setStmt(Stmt *S) {
-    assert(IsSemiMissing && "Operation supported for printing values only!");
-    Statement = S;
-  }
+  void setStmt(Stmt *S);
   bool isSemiMissing() const { return IsSemiMissing; }
   void setSemiMissing(bool Missing = true) { IsSemiMissing = Missing; }
 
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classofKind(Kind K) { return K == TopLevelStmt; }
+
+  static DeclContext *castToDeclContext(const TopLevelStmtDecl *D) {
+    return static_cast<DeclContext *>(const_cast<TopLevelStmtDecl *>(D));
+  }
+  static TopLevelStmtDecl *castFromDeclContext(const DeclContext *DC) {
+    return static_cast<TopLevelStmtDecl *>(const_cast<DeclContext *>(DC));
+  }
 };
 
 /// Represents a block literal declaration, which is like an
diff --git a/clang/include/clang/AST/DeclBase.h b/clang/include/clang/AST/DeclBase.h
index 9a4736019d1b1b..76810a86a78a46 100644
--- a/clang/include/clang/AST/DeclBase.h
+++ b/clang/include/clang/AST/DeclBase.h
@@ -2120,6 +2120,7 @@ class DeclContext {
     case Decl::Block:
     case Decl::Captured:
     case Decl::ObjCMethod:
+    case Decl::TopLevelStmt:
       return true;
     default:
       return getDeclKind() >= Decl::firstFunction &&
diff --git a/clang/include/clang/Basic/DeclNodes.td b/clang/include/clang/Basic/DeclNodes.td
index 8b1f415dd5fe2c..48396e85c5adac 100644
--- a/clang/include/clang/Basic/DeclNodes.td
+++ b/clang/include/clang/Basic/DeclNodes.td
@@ -95,7 +95,7 @@ def LinkageSpec : DeclNode<Decl>, DeclContext;
 def Export : DeclNode<Decl>, DeclContext;
 def ObjCPropertyImpl : DeclNode<Decl>;
 def FileScopeAsm : DeclNode<Decl>;
-def TopLevelStmt : DeclNode<Decl>;
+def TopLevelStmt : DeclNode<Decl>, DeclContext;
 def AccessSpec : DeclNode<Decl>;
 def Friend : DeclNode<Decl>;
 def FriendTemplate : DeclNode<Decl>;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index ef4b93fac95ce5..db45de107163a2 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -3307,7 +3307,8 @@ class Sema final {
                               SourceLocation AsmLoc,
                               SourceLocation RParenLoc);
 
-  Decl *ActOnTopLevelStmtDecl(Stmt *Statement);
+  TopLevelStmtDecl *ActOnStartTopLevelStmtDecl(Scope *S);
+  void ActOnFinishTopLevelStmtDecl(TopLevelStmtDecl *D, Stmt *Statement);
 
   /// Handle a C++11 empty-declaration and attribute-declaration.
   Decl *ActOnEmptyDeclaration(Scope *S, const ParsedAttributesView &AttrList,
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 5d6bb72a208a1a..5f2edee3e60a0d 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -5539,14 +5539,13 @@ FileScopeAsmDecl *FileScopeAsmDecl::CreateDeserialized(ASTContext &C,
 void TopLevelStmtDecl::anchor() {}
 
 TopLevelStmtDecl *TopLevelStmtDecl::Create(ASTContext &C, Stmt *Statement) {
-  assert(Statement);
   assert(C.getLangOpts().IncrementalExtensions &&
          "Must be used only in incremental mode");
 
-  SourceLocation BeginLoc = Statement->getBeginLoc();
+  SourceLocation Loc = Statement ? Statement->getBeginLoc() : SourceLocation();
   DeclContext *DC = C.getTranslationUnitDecl();
 
-  return new (C, DC) TopLevelStmtDecl(DC, BeginLoc, Statement);
+  return new (C, DC) TopLevelStmtDecl(DC, Loc, Statement);
 }
 
 TopLevelStmtDecl *TopLevelStmtDecl::CreateDeserialized(ASTContext &C,
@@ -5559,6 +5558,12 @@ SourceRange TopLevelStmtDecl::getSourceRange() const {
   return SourceRange(getLocation(), Statement->getEndLoc());
 }
 
+void TopLevelStmtDecl::setStmt(Stmt *S) {
+  assert(S);
+  Statement = S;
+  setLocation(Statement->getBeginLoc());
+}
+
 void EmptyDecl::anchor() {}
 
 EmptyDecl *EmptyDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L) {
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 10fe8bb97ce660..fcedb3cfd176a0 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -1352,6 +1352,7 @@ DeclContext *DeclContext::getPrimaryContext() {
   case Decl::ExternCContext:
   case Decl::LinkageSpec:
   case Decl::Export:
+  case Decl::TopLevelStmt:
   case Decl::Block:
   case Decl::Captured:
   case Decl::OMPDeclareReduction:
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index edfab11c37cf0f..25634a5889271e 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -5676,24 +5676,32 @@ Parser::DeclGroupPtrTy Parser::ParseTopLevelStmtDecl() {
   // Parse a top-level-stmt.
   Parser::StmtVector Stmts;
   ParsedStmtContext SubStmtCtx = ParsedStmtContext();
-  Actions.PushFunctionScope();
+  ParseScope FnScope(this, Scope::FnScope | Scope::DeclScope |
+                               Scope::CompoundStmtScope);
+  TopLevelStmtDecl *TLSD = Actions.ActOnStartTopLevelStmtDecl(getCurScope());
   StmtResult R = ParseStatementOrDeclaration(Stmts, SubStmtCtx);
-  Actions.PopFunctionScopeInfo();
   if (!R.isUsable())
     return nullptr;
 
-  SmallVector<Decl *, 2> DeclsInGroup;
-  DeclsInGroup.push_back(Actions.ActOnTopLevelStmtDecl(R.get()));
+  Actions.ActOnFinishTopLevelStmtDecl(TLSD, R.get());
 
   if (Tok.is(tok::annot_repl_input_end) &&
       Tok.getAnnotationValue() != nullptr) {
     ConsumeAnnotationToken();
-    cast<TopLevelStmtDecl>(DeclsInGroup.back())->setSemiMissing();
+    TLSD->setSemiMissing();
   }
 
-  // Currently happens for things like  -fms-extensions and use `__if_exists`.
-  for (Stmt *S : Stmts)
-    DeclsInGroup.push_back(Actions.ActOnTopLevelStmtDecl(S));
+  SmallVector<Decl *, 2> DeclsInGroup;
+  DeclsInGroup.push_back(TLSD);
+
+  // Currently happens for things like -fms-extensions and use `__if_exists`.
+  for (Stmt *S : Stmts) {
+    // Here we should be safe as `__if_exists` and friends are not introducing
+    // new variables which need to live outside file scope.
+    TopLevelStmtDecl *D = Actions.ActOnStartTopLevelStmtDecl(getCurScope());
+    Actions.ActOnFinishTopLevelStmtDecl(D, S);
+    DeclsInGroup.push_back(D);
+  }
 
   return Actions.BuildDeclaratorGroup(DeclsInGroup);
 }
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 9fdd8eb236d1ee..438a4b7fbe844a 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -20446,12 +20446,22 @@ Decl *Sema::ActOnFileScopeAsmDecl(Expr *expr,
   return New;
 }
 
-Decl *Sema::ActOnTopLevelStmtDecl(Stmt *Statement) {
-  auto *New = TopLevelStmtDecl::Create(Context, Statement);
-  Context.getTranslationUnitDecl()->addDecl(New);
+TopLevelStmtDecl *Sema::ActOnStartTopLevelStmtDecl(Scope *S) {
+  auto *New = TopLevelStmtDecl::Create(Context, /*Statement=*/nullptr);
+  CurContext->addDecl(New);
+  PushDeclContext(S, New);
+  PushFunctionScope();
+  PushCompoundScope(false);
   return New;
 }
 
+void Sema::ActOnFinishTopLevelStmtDecl(TopLevelStmtDecl *D, Stmt *Statement) {
+  D->setStmt(Statement);
+  PopCompoundScope();
+  PopFunctionScopeInfo();
+  PopDeclContext();
+}
+
 void Sema::ActOnPragmaRedefineExtname(IdentifierInfo* Name,
                                       IdentifierInfo* AliasName,
                                       SourceLocation PragmaLoc,
diff --git a/clang/test/Interpreter/execute-stmts.cpp b/clang/test/Interpreter/execute-stmts.cpp
index 2d4c17e0c91e66..e341b06d154f18 100644
--- a/clang/test/Interpreter/execute-stmts.cpp
+++ b/clang/test/Interpreter/execute-stmts.cpp
@@ -9,7 +9,6 @@
 //CODEGEN-CHECK-COUNT-2: define internal void @__stmts__
 //CODEGEN-CHECK-NOT: define internal void @__stmts__
 
-
 extern "C" int printf(const char*,...);
 
 template <typename T> T call() { printf("called\n"); return T(); }
@@ -41,3 +40,16 @@ for (; i > 4; --i) { printf("i = %d\n", i); };
 
 int j = i; printf("j = %d\n", j);
 // CHECK-NEXT: j = 4
+
+if (int i = j) printf("i = %d\n", i);
+// CHECK-NEXT: i = 4
+
+for (int i = j; i > 3; --i) printf("i = %d\n", i);
+// CHECK-NEXT: i = 4
+
+for(int i=0; i<2; i+=1) {};
+
+for(int i=0; i<2; i+=1) ;
+
+int *aa=nullptr;
+if (auto *b=aa) *b += 1;

``````````

</details>


https://github.com/llvm/llvm-project/pull/84150


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