Place implictly declared functions at block scope

Such implicitly declared functions behave as if the enclosing block
contained the declaration extern int name() (C90, 6.3.3.2 Function calls),
thus their names should have block scope (C90, 6.1.2.1 Scope of identifiers).

This patch fixes https://bugs.llvm.org/show_bug.cgi?id=33224

Differential Revision: https://reviews.llvm.org/D33676



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@310616 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Sema/Scope.h

@@ -124,6 +124,9 @@ public:
 
     /// We are currently in the filter expression of an SEH except block.
     SEHFilterScope = 0x200000,
+
+    /// This is a compound statement scope.
+    CompoundStmtScope = 0x400000,
   };
 private:
   /// The parent scope for this scope.  This is null for the translation-unit
@@ -429,6 +432,11 @@ public:
   /// \brief Determine whether this scope is a SEH '__except' block.
   bool isSEHExceptScope() const { return getFlags() & Scope::SEHExceptScope; }
 
+  /// \brief Determine whether this scope is a compound statement scope.
+  bool isCompoundStmtScope() const {
+    return getFlags() & Scope::CompoundStmtScope;
+  }
+
   /// \brief Returns if rhs has a higher scope depth than this.
   ///
   /// The caller is responsible for calling this only if one of the two scopes

lib/Parse/ParseCXXInlineMethods.cpp

@@ -518,7 +518,8 @@ void Parser::ParseLexedMethodDef(LexedMethod &LM) {
 
   // Parse the method body. Function body parsing code is similar enough
   // to be re-used for method bodies as well.
-  ParseScope FnScope(this, Scope::FnScope|Scope::DeclScope);
+  ParseScope FnScope(this, Scope::FnScope | Scope::DeclScope |
+                               Scope::CompoundStmtScope);
   Actions.ActOnStartOfFunctionDef(getCurScope(), LM.D);
 
   if (Tok.is(tok::kw_try)) {

lib/Parse/ParseDecl.cpp

@@ -1388,7 +1388,9 @@ void Parser::ParseLexedAttribute(LateParsedAttribute &LA,
 
       // If the Decl is on a function, add function parameters to the scope.
       bool HasFunScope = EnterScope && D->isFunctionOrFunctionTemplate();
-      ParseScope FnScope(this, Scope::FnScope|Scope::DeclScope, HasFunScope);
+      ParseScope FnScope(
+          this, Scope::FnScope | Scope::DeclScope | Scope::CompoundStmtScope,
+          HasFunScope);
       if (HasFunScope)
         Actions.ActOnReenterFunctionContext(Actions.CurScope, D);
 

lib/Parse/ParseExpr.cpp

@@ -2881,7 +2881,7 @@ ExprResult Parser::ParseBlockLiteralExpression() {
   // allows determining whether a variable reference inside the block is
   // within or outside of the block.
   ParseScope BlockScope(this, Scope::BlockScope | Scope::FnScope |
-                              Scope::DeclScope);
+                                  Scope::CompoundStmtScope | Scope::DeclScope);
 
   // Inform sema that we are starting a block.
   Actions.ActOnBlockStart(CaretLoc, getCurScope());

lib/Parse/ParseExprCXX.cpp

@@ -1281,7 +1281,8 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
 
   // FIXME: Rename BlockScope -> ClosureScope if we decide to continue using
   // it.
-  unsigned ScopeFlags = Scope::BlockScope | Scope::FnScope | Scope::DeclScope;
+  unsigned ScopeFlags = Scope::BlockScope | Scope::FnScope | Scope::DeclScope |
+                        Scope::CompoundStmtScope;
   ParseScope BodyScope(this, ScopeFlags);
 
   Actions.ActOnStartOfLambdaDefinition(Intro, D, getCurScope());

lib/Parse/ParseObjc.cpp

@@ -2478,7 +2478,7 @@ Parser::ParseObjCSynchronizedStmt(SourceLocation atLoc) {
     operand = Actions.ActOnObjCAtSynchronizedOperand(atLoc, operand.get());
 
   // Parse the compound statement within a new scope.
-  ParseScope bodyScope(this, Scope::DeclScope);
+  ParseScope bodyScope(this, Scope::DeclScope | Scope::CompoundStmtScope);
   StmtResult body(ParseCompoundStatementBody());
   bodyScope.Exit();
 
@@ -2514,7 +2514,7 @@ StmtResult Parser::ParseObjCTryStmt(SourceLocation atLoc) {
   }
   StmtVector CatchStmts;
   StmtResult FinallyStmt;
-  ParseScope TryScope(this, Scope::DeclScope);
+  ParseScope TryScope(this, Scope::DeclScope | Scope::CompoundStmtScope);
   StmtResult TryBody(ParseCompoundStatementBody());
   TryScope.Exit();
   if (TryBody.isInvalid())
@@ -2535,7 +2535,9 @@ StmtResult Parser::ParseObjCTryStmt(SourceLocation atLoc) {
       ConsumeToken(); // consume catch
       if (Tok.is(tok::l_paren)) {
         ConsumeParen();
-        ParseScope CatchScope(this, Scope::DeclScope|Scope::AtCatchScope);
+        ParseScope CatchScope(this, Scope::DeclScope |
+                                        Scope::CompoundStmtScope |
+                                        Scope::AtCatchScope);
         if (Tok.isNot(tok::ellipsis)) {
           DeclSpec DS(AttrFactory);
           ParseDeclarationSpecifiers(DS);
@@ -2579,7 +2581,8 @@ StmtResult Parser::ParseObjCTryStmt(SourceLocation atLoc) {
     } else {
       assert(Tok.isObjCAtKeyword(tok::objc_finally) && "Lookahead confused?");
       ConsumeToken(); // consume finally
-      ParseScope FinallyScope(this, Scope::DeclScope);
+      ParseScope FinallyScope(this,
+                              Scope::DeclScope | Scope::CompoundStmtScope);
 
       StmtResult FinallyBody(true);
       if (Tok.is(tok::l_brace))
@@ -2616,7 +2619,7 @@ Parser::ParseObjCAutoreleasePoolStmt(SourceLocation atLoc) {
   }
   // Enter a scope to hold everything within the compound stmt.  Compound
   // statements can always hold declarations.
-  ParseScope BodyScope(this, Scope::DeclScope);
+  ParseScope BodyScope(this, Scope::DeclScope | Scope::CompoundStmtScope);
 
   StmtResult AutoreleasePoolBody(ParseCompoundStatementBody());
 
@@ -3650,11 +3653,10 @@ void Parser::ParseLexedObjCMethodDefs(LexedMethod &LM, bool parseMethod) {
   assert(Tok.isOneOf(tok::l_brace, tok::kw_try, tok::colon) && 
          "Inline objective-c method not starting with '{' or 'try' or ':'");
   // Enter a scope for the method or c-function body.
-  ParseScope BodyScope(this,
-                       parseMethod
-                       ? Scope::ObjCMethodScope|Scope::FnScope|Scope::DeclScope
-                       : Scope::FnScope|Scope::DeclScope);
-    
+  ParseScope BodyScope(this, (parseMethod ? Scope::ObjCMethodScope : 0) |
+                                 Scope::FnScope | Scope::DeclScope |
+                                 Scope::CompoundStmtScope);
+
   // Tell the actions module that we have entered a method or c-function definition 
   // with the specified Declarator for the method/function.
   if (parseMethod)

lib/Parse/ParseOpenMP.cpp

@@ -302,6 +302,7 @@ Parser::ParseOpenMPDeclareReductionDirective(AccessSpecifier AS) {
   for (auto *D : DRD.get()) {
     TentativeParsingAction TPA(*this);
     ParseScope OMPDRScope(this, Scope::FnScope | Scope::DeclScope |
+                                    Scope::CompoundStmtScope |
                                     Scope::OpenMPDirectiveScope);
     // Parse <combiner> expression.
     Actions.ActOnOpenMPDeclareReductionCombinerStart(getCurScope(), D);
@@ -337,6 +338,7 @@ Parser::ParseOpenMPDeclareReductionDirective(AccessSpecifier AS) {
           IsCorrect;
       if (Tok.isNot(tok::annot_pragma_openmp_end)) {
         ParseScope OMPDRScope(this, Scope::FnScope | Scope::DeclScope |
+                                        Scope::CompoundStmtScope |
                                         Scope::OpenMPDirectiveScope);
         // Parse expression.
         Actions.ActOnOpenMPDeclareReductionInitializerStart(getCurScope(), D);
@@ -405,8 +407,9 @@ public:
 
     // If the Decl is on a function, add function parameters to the scope.
     HasFunScope = D->isFunctionOrFunctionTemplate();
-    FnScope = new Parser::ParseScope(&P, Scope::FnScope | Scope::DeclScope,
-                                     HasFunScope);
+    FnScope = new Parser::ParseScope(
+        &P, Scope::FnScope | Scope::DeclScope | Scope::CompoundStmtScope,
+        HasFunScope);
     if (HasFunScope)
       Actions.ActOnReenterFunctionContext(Actions.getCurScope(), D);
   }
@@ -813,8 +816,8 @@ StmtResult Parser::ParseOpenMPDeclarativeOrExecutableDirective(
   SmallVector<OMPClause *, 5> Clauses;
   SmallVector<llvm::PointerIntPair<OMPClause *, 1, bool>, OMPC_unknown + 1>
   FirstClauses(OMPC_unknown + 1);
-  unsigned ScopeFlags =
-      Scope::FnScope | Scope::DeclScope | Scope::OpenMPDirectiveScope;
+  unsigned ScopeFlags = Scope::FnScope | Scope::DeclScope |
+                        Scope::CompoundStmtScope | Scope::OpenMPDirectiveScope;
   SourceLocation Loc = ConsumeAnnotationToken(), EndLoc;
   auto DKind = ParseOpenMPDirectiveKind(*this);
   OpenMPDirectiveKind CancelRegion = OMPD_unknown;

lib/Parse/ParsePragma.cpp

@@ -533,7 +533,8 @@ StmtResult Parser::HandlePragmaCaptured()
 
   SourceLocation Loc = Tok.getLocation();
 
-  ParseScope CapturedRegionScope(this, Scope::FnScope | Scope::DeclScope);
+  ParseScope CapturedRegionScope(this, Scope::FnScope | Scope::DeclScope |
+                                           Scope::CompoundStmtScope);
   Actions.ActOnCapturedRegionStart(Loc, getCurScope(), CR_Default,
                                    /*NumParams=*/1);
 

lib/Parse/ParseStmt.cpp

@@ -453,9 +453,10 @@ StmtResult Parser::ParseSEHTryBlock() {
   if (Tok.isNot(tok::l_brace))
     return StmtError(Diag(Tok, diag::err_expected) << tok::l_brace);
 
-  StmtResult TryBlock(ParseCompoundStatement(/*isStmtExpr=*/false,
-                      Scope::DeclScope | Scope::SEHTryScope));
-  if(TryBlock.isInvalid())
+  StmtResult TryBlock(ParseCompoundStatement(
+      /*isStmtExpr=*/false,
+      Scope::DeclScope | Scope::CompoundStmtScope | Scope::SEHTryScope));
+  if (TryBlock.isInvalid())
     return TryBlock;
 
   StmtResult Handler;
@@ -840,7 +841,8 @@ StmtResult Parser::ParseDefaultStatement() {
 }
 
 StmtResult Parser::ParseCompoundStatement(bool isStmtExpr) {
-  return ParseCompoundStatement(isStmtExpr, Scope::DeclScope);
+  return ParseCompoundStatement(isStmtExpr,
+                                Scope::DeclScope | Scope::CompoundStmtScope);
 }
 
 /// ParseCompoundStatement - Parse a "{}" block.
@@ -2085,9 +2087,10 @@ StmtResult Parser::ParseCXXTryBlockCommon(SourceLocation TryLoc, bool FnTry) {
   if (Tok.isNot(tok::l_brace))
     return StmtError(Diag(Tok, diag::err_expected) << tok::l_brace);
 
-  StmtResult TryBlock(ParseCompoundStatement(/*isStmtExpr=*/false,
-                      Scope::DeclScope | Scope::TryScope |
-                        (FnTry ? Scope::FnTryCatchScope : 0)));
+  StmtResult TryBlock(ParseCompoundStatement(
+      /*isStmtExpr=*/false, Scope::DeclScope | Scope::TryScope |
+                                Scope::CompoundStmtScope |
+                                (FnTry ? Scope::FnTryCatchScope : 0)));
   if (TryBlock.isInvalid())
     return TryBlock;
 

lib/Parse/ParseTemplate.cpp

@@ -1380,7 +1380,8 @@ void Parser::ParseLateTemplatedFuncDef(LateParsedTemplate &LPT) {
 
   // Parse the method body. Function body parsing code is similar enough
   // to be re-used for method bodies as well.
-  ParseScope FnScope(this, Scope::FnScope|Scope::DeclScope);
+  ParseScope FnScope(this, Scope::FnScope | Scope::DeclScope |
+                               Scope::CompoundStmtScope);
 
   // Recreate the containing function DeclContext.
   Sema::ContextRAII FunctionSavedContext(Actions,

lib/Parse/Parser.cpp

@@ -1075,8 +1075,9 @@ Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
       TemplateInfo.Kind == ParsedTemplateInfo::Template &&
       Actions.canDelayFunctionBody(D)) {
     MultiTemplateParamsArg TemplateParameterLists(*TemplateInfo.TemplateParams);
-    
-    ParseScope BodyScope(this, Scope::FnScope|Scope::DeclScope);
+
+    ParseScope BodyScope(this, Scope::FnScope | Scope::DeclScope |
+                                   Scope::CompoundStmtScope);
     Scope *ParentScope = getCurScope()->getParent();
 
     D.setFunctionDefinitionKind(FDK_Definition);
@@ -1106,7 +1107,8 @@ Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
            (Tok.is(tok::l_brace) || Tok.is(tok::kw_try) ||
             Tok.is(tok::colon)) && 
       Actions.CurContext->isTranslationUnit()) {
-    ParseScope BodyScope(this, Scope::FnScope|Scope::DeclScope);
+    ParseScope BodyScope(this, Scope::FnScope | Scope::DeclScope |
+                                   Scope::CompoundStmtScope);
     Scope *ParentScope = getCurScope()->getParent();
 
     D.setFunctionDefinitionKind(FDK_Definition);
@@ -1124,7 +1126,8 @@ Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
   }
 
   // Enter a scope for the function body.
-  ParseScope BodyScope(this, Scope::FnScope|Scope::DeclScope);
+  ParseScope BodyScope(this, Scope::FnScope | Scope::DeclScope |
+                                 Scope::CompoundStmtScope);
 
   // Tell the actions module that we have entered a function definition with the
   // specified Declarator for the function.

lib/Sema/SemaDecl.cpp

@@ -12677,12 +12677,16 @@ NamedDecl *Sema::ImplicitlyDefineFunction(SourceLocation Loc,
                 SourceLocation());
   D.SetIdentifier(&II, Loc);
 
-  // Insert this function into translation-unit scope.
+  // Insert this function into the enclosing block scope.
+  while (S && !S->isCompoundStmtScope())
+    S = S->getParent();
+  if (S == nullptr)
+    S = TUScope;
 
   DeclContext *PrevDC = CurContext;
   CurContext = Context.getTranslationUnitDecl();
 
-  FunctionDecl *FD = cast<FunctionDecl>(ActOnDeclarator(TUScope, D));
+  FunctionDecl *FD = cast<FunctionDecl>(ActOnDeclarator(S, D));
   FD->setImplicit();
 
   CurContext = PrevDC;

test/Sema/implicit-decl-c90.c

@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 %s -std=c90 -verify -fsyntax-only
+void t0(int x) {
+  int (*p)();
+  if(x > 0)
+    x = g() + 1;
+  p = g;
+  if(x < 0) {
+    extern void u(int (*)[h()]);
+    int (*q)() = h;
+  }
+  p = h; /* expected-error {{use of undeclared identifier 'h'}} */
+}
+
+void t1(int x) {
+  int (*p)();
+  switch (x) {
+    g();
+  case 0:
+    x = h() + 1;
+    break;
+  case 1:
+    p = g;
+    p = h;
+    break;
+  }
+  p = g; /* expected-error {{use of undeclared identifier 'g'}} */
+  p = h; /* expected-error {{use of undeclared identifier 'h'}} */
+}
+
+int t2(int x) {
+  int y = ({ if (x > 0) x = g() + 1; 2*x; });
+  int (*p)() = g; /* expected-error {{use of undeclared identifier 'g'}} */
+  return y;
+}
+
+int (*p)() = g; /* expected-error {{use of undeclared identifier 'g'}} */
+int (*q)() = h; /* expected-error {{use of undeclared identifier 'h'}} */
+
+float g(); /* not expecting conflicting types diagnostics here */

test/Sema/implicit-decl.c

@@ -9,8 +9,7 @@ void func() {
    int32_t *vector[16];
    const char compDesc[16 + 1];
    int32_t compCount = 0;
-   if (_CFCalendarDecomposeAbsoluteTimeV(compDesc, vector, compCount)) { // expected-note {{previous implicit declaration is here}} \
-         expected-error {{implicit declaration of function '_CFCalendarDecomposeAbsoluteTimeV' is invalid in C99}}
+   if (_CFCalendarDecomposeAbsoluteTimeV(compDesc, vector, compCount)) { // expected-error {{implicit declaration of function '_CFCalendarDecomposeAbsoluteTimeV' is invalid in C99}}
    }
 
    printg("Hello, World!\n"); // expected-error{{implicit declaration of function 'printg' is invalid in C99}} \
@@ -18,7 +17,7 @@ void func() {
 
   __builtin_is_les(1, 3); // expected-error{{use of unknown builtin '__builtin_is_les'}}
 }
-Boolean _CFCalendarDecomposeAbsoluteTimeV(const char *componentDesc, int32_t **vector, int32_t count) { // expected-error{{conflicting types for '_CFCalendarDecomposeAbsoluteTimeV'}}
+Boolean _CFCalendarDecomposeAbsoluteTimeV(const char *componentDesc, int32_t **vector, int32_t count) {
  return 0;
 }