[cfe-commits] r97497 - in /cfe/trunk: include/clang/Basic/DiagnosticSemaKinds.td lib/Sema/JumpDiagnostics.cpp lib/Sema/Sema.cpp lib/Sema/Sema.h lib/Sema/SemaDecl.cpp lib/Sema/SemaDeclObjC.cpp lib/Sema/SemaExpr.cpp test/SemaCXX/statements.cpp
Douglas Gregor
dgregor at apple.com
Mon Mar 1 13:11:54 PST 2010
On Mar 1, 2010, at 12:59 PM, Chris Lattner wrote:
> Author: lattner
> Date: Mon Mar 1 14:59:53 2010
> New Revision: 97497
>
> URL: http://llvm.org/viewvc/llvm-project?rev=97497&view=rev
> Log:
> Implement jump checking for initialized c++ variables, implementing
> a fixme and PR6451.
>
> Only perform jump checking if the containing function has no errors,
> and add the infrastructure needed to do this.
>
> On the testcase in the PR, we produce:
>
> t.cc:6:3: error: illegal goto into protected scope
> goto later;
> ^
> t.cc:7:5: note: jump bypasses variable initialization
> X x;
> ^
Very nice, thanks!
>
> Modified:
> cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> cfe/trunk/lib/Sema/JumpDiagnostics.cpp
> cfe/trunk/lib/Sema/Sema.cpp
> cfe/trunk/lib/Sema/Sema.h
> cfe/trunk/lib/Sema/SemaDecl.cpp
> cfe/trunk/lib/Sema/SemaDeclObjC.cpp
> cfe/trunk/lib/Sema/SemaExpr.cpp
> cfe/trunk/test/SemaCXX/statements.cpp
>
> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=97497&r1=97496&r2=97497&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Mon Mar 1 14:59:53 2010
> @@ -1592,6 +1592,8 @@
> def err_addr_of_label_in_protected_scope : Error<
> "address taken of label in protected scope, jump to it would have "
> "unknown effect on scope">;
> +def note_protected_by_variable_init : Note<
> + "jump bypasses variable initialization">;
> def note_protected_by_vla_typedef : Note<
> "jump bypasses initialization of VLA typedef">;
> def note_protected_by_vla : Note<
>
> Modified: cfe/trunk/lib/Sema/JumpDiagnostics.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/JumpDiagnostics.cpp?rev=97497&r1=97496&r2=97497&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/JumpDiagnostics.cpp (original)
> +++ cfe/trunk/lib/Sema/JumpDiagnostics.cpp Mon Mar 1 14:59:53 2010
> @@ -77,7 +77,7 @@
>
> /// GetDiagForGotoScopeDecl - If this decl induces a new goto scope, return a
> /// diagnostic that should be emitted if control goes over it. If not, return 0.
> -static unsigned GetDiagForGotoScopeDecl(const Decl *D) {
> +static unsigned GetDiagForGotoScopeDecl(const Decl *D, bool isCPlusPlus) {
> if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
> if (VD->getType()->isVariablyModifiedType())
> return diag::note_protected_by_vla;
> @@ -85,6 +85,9 @@
> return diag::note_protected_by_cleanup;
> if (VD->hasAttr<BlocksAttr>())
> return diag::note_protected_by___block;
> + if (isCPlusPlus && VD->hasLocalStorage() && VD->hasInit())
> + return diag::note_protected_by_variable_init;
> +
> } else if (const TypedefDecl *TD = dyn_cast<TypedefDecl>(D)) {
> if (TD->getUnderlyingType()->isVariablyModifiedType())
> return diag::note_protected_by_vla_typedef;
> @@ -116,18 +119,17 @@
> Stmt *SubStmt = *CI;
> if (SubStmt == 0) continue;
>
> - // FIXME: diagnose jumps past initialization: required in C++, warning in C.
> - // goto L; int X = 4; L: ;
> + bool isCPlusPlus = this->S.getLangOptions().CPlusPlus;
>
> // If this is a declstmt with a VLA definition, it defines a scope from here
> // to the end of the containing context.
> if (DeclStmt *DS = dyn_cast<DeclStmt>(SubStmt)) {
> - // The decl statement creates a scope if any of the decls in it are VLAs or
> - // have the cleanup attribute.
> + // The decl statement creates a scope if any of the decls in it are VLAs
> + // or have the cleanup attribute.
> for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
> I != E; ++I) {
> // If this decl causes a new scope, push and switch to it.
> - if (unsigned Diag = GetDiagForGotoScopeDecl(*I)) {
> + if (unsigned Diag = GetDiagForGotoScopeDecl(*I, isCPlusPlus)) {
> Scopes.push_back(GotoScope(ParentScope, Diag, (*I)->getLocation()));
> ParentScope = Scopes.size()-1;
> }
>
> Modified: cfe/trunk/lib/Sema/Sema.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/Sema.cpp?rev=97497&r1=97496&r2=97497&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/Sema.cpp (original)
> +++ cfe/trunk/lib/Sema/Sema.cpp Mon Mar 1 14:59:53 2010
> @@ -127,6 +127,8 @@
> if (getLangOptions().CPlusPlus)
> FieldCollector.reset(new CXXFieldCollector());
>
> + NumErrorsAtStartOfFunction = 0;
> +
> // Tell diagnostics how to render things from the AST library.
> PP.getDiagnostics().SetArgToStringFn(&FormatASTNodeDiagnosticArgument,
> &Context);
>
> Modified: cfe/trunk/lib/Sema/Sema.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/Sema.h?rev=97497&r1=97496&r2=97497&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/Sema.h (original)
> +++ cfe/trunk/lib/Sema/Sema.h Mon Mar 1 14:59:53 2010
> @@ -147,6 +147,10 @@
> /// return types, if any, in the block body.
> QualType ReturnType;
>
> + /// SavedNumErrorsAtStartOfFunction - This is the value of the
> + /// NumErrorsAtStartOfFunction variable at the point when the block started.
> + unsigned SavedNumErrorsAtStartOfFunction;
> +
> /// SavedFunctionNeedsScopeChecking - This is the value of
> /// CurFunctionNeedsScopeChecking at the point when the block started.
> bool SavedFunctionNeedsScopeChecking;
> @@ -241,6 +245,13 @@
> /// the current full expression.
> llvm::SmallVector<CXXTemporary*, 8> ExprTemporaries;
>
> + /// NumErrorsAtStartOfFunction - This is the number of errors that were
> + /// emitted to the diagnostics object at the start of the current
> + /// function/method definition. If no additional errors are emitted by the
> + /// end of the function, we assume the AST is well formed enough to be
> + /// worthwhile to emit control flow diagnostics.
> + unsigned NumErrorsAtStartOfFunction;
> +
> /// CurFunctionNeedsScopeChecking - This is set to true when a function or
> /// ObjC method body contains a VLA or an ObjC try block, which introduce
> /// scopes that need to be checked for goto conditions. If a function does
>
> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=97497&r1=97496&r2=97497&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Mon Mar 1 14:59:53 2010
> @@ -850,7 +850,7 @@
> // is normally mapped to an error, but can be controlled with
> // -Wtypedef-redefinition. If either the original or the redefinition is
> // in a system header, don't emit this for compatibility with GCC.
> - if (PP.getDiagnostics().getSuppressSystemWarnings() &&
> + if (getDiagnostics().getSuppressSystemWarnings() &&
> (Context.getSourceManager().isInSystemHeader(Old->getLocation()) ||
> Context.getSourceManager().isInSystemHeader(New->getLocation())))
> return;
> @@ -2500,7 +2500,12 @@
>
> bool isVM = T->isVariablyModifiedType();
> if (isVM || NewVD->hasAttr<CleanupAttr>() ||
> - NewVD->hasAttr<BlocksAttr>())
> + NewVD->hasAttr<BlocksAttr>() ||
> + // FIXME: We need to diagnose jumps passed initialized variables in C++.
> + // However, this turns on the scope checker for everything with a variable
> + // which may impact compile time. See if we can find a better solution
> + // to this, perhaps only checking functions that contain gotos in C++?
> + (LangOpts.CPlusPlus && NewVD->hasLocalStorage()))
> CurFunctionNeedsScopeChecking = true;
>
> if ((isVM && NewVD->hasLinkage()) ||
> @@ -4079,6 +4084,7 @@
> FD = cast<FunctionDecl>(D.getAs<Decl>());
>
> CurFunctionNeedsScopeChecking = false;
> + NumErrorsAtStartOfFunction = getDiagnostics().getNumErrors();
>
> // See if this is a redefinition.
> // But don't complain if we're in GNU89 mode and the previous definition
> @@ -4257,7 +4263,8 @@
> CheckUnreachable(AC);
>
> // Verify that that gotos and switch cases don't jump into scopes illegally.
> - if (CurFunctionNeedsScopeChecking)
> + if (CurFunctionNeedsScopeChecking &&
> + NumErrorsAtStartOfFunction == getDiagnostics().getNumErrors())
> DiagnoseInvalidJumps(Body);
>
> // C++ constructors that have function-try-blocks can't have return
> @@ -4272,7 +4279,7 @@
> // If any errors have occurred, clear out any temporaries that may have
> // been leftover. This ensures that these temporaries won't be picked up for
> // deletion in some later function.
> - if (PP.getDiagnostics().hasErrorOccurred())
> + if (getDiagnostics().hasErrorOccurred())
> ExprTemporaries.clear();
>
> assert(ExprTemporaries.empty() && "Leftover temporaries in function");
>
> Modified: cfe/trunk/lib/Sema/SemaDeclObjC.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclObjC.cpp?rev=97497&r1=97496&r2=97497&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaDeclObjC.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaDeclObjC.cpp Mon Mar 1 14:59:53 2010
> @@ -50,6 +50,7 @@
> return;
>
> CurFunctionNeedsScopeChecking = false;
> + NumErrorsAtStartOfFunction = getDiagnostics().getNumErrors();
>
> // Allow the rest of sema to find private method decl implementations.
> if (MDecl->isInstanceMethod())
>
> Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=97497&r1=97496&r2=97497&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaExpr.cpp Mon Mar 1 14:59:53 2010
> @@ -6734,8 +6734,10 @@
> BSI->hasBlockDeclRefExprs = false;
> BSI->hasPrototype = false;
> BSI->SavedFunctionNeedsScopeChecking = CurFunctionNeedsScopeChecking;
> + BSI->SavedNumErrorsAtStartOfFunction = NumErrorsAtStartOfFunction;
> CurFunctionNeedsScopeChecking = false;
> -
> + NumErrorsAtStartOfFunction = getDiagnostics().getNumErrors();
> +
> BSI->TheDecl = BlockDecl::Create(Context, CurContext, CaretLoc);
> CurContext->addDecl(BSI->TheDecl);
> PushDeclContext(BlockScope, BSI->TheDecl);
> @@ -6849,6 +6851,7 @@
> llvm::OwningPtr<BlockScopeInfo> CC(CurBlock);
>
> CurFunctionNeedsScopeChecking = CurBlock->SavedFunctionNeedsScopeChecking;
> + NumErrorsAtStartOfFunction = CurBlock->SavedNumErrorsAtStartOfFunction;
>
> // Pop off CurBlock, handle nested blocks.
> PopDeclContext();
> @@ -6895,9 +6898,12 @@
> BlockTy = Context.getBlockPointerType(BlockTy);
>
> // If needed, diagnose invalid gotos and switches in the block.
> - if (CurFunctionNeedsScopeChecking)
> + if (CurFunctionNeedsScopeChecking &&
> + NumErrorsAtStartOfFunction == getDiagnostics().getNumErrors())
> DiagnoseInvalidJumps(static_cast<CompoundStmt*>(body.get()));
> +
> CurFunctionNeedsScopeChecking = BSI->SavedFunctionNeedsScopeChecking;
> + NumErrorsAtStartOfFunction = BSI->SavedNumErrorsAtStartOfFunction;
>
> BSI->TheDecl->setBody(body.takeAs<CompoundStmt>());
>
>
> Modified: cfe/trunk/test/SemaCXX/statements.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/statements.cpp?rev=97497&r1=97496&r2=97497&view=diff
> ==============================================================================
> --- cfe/trunk/test/SemaCXX/statements.cpp (original)
> +++ cfe/trunk/test/SemaCXX/statements.cpp Mon Mar 1 14:59:53 2010
> @@ -1,5 +1,17 @@
> -// RUN: %clang_cc1 %s -fsyntax-only -pedantic
> +// RUN: %clang_cc1 %s -fsyntax-only -pedantic -verify
>
> void foo() {
> return foo();
> }
> +
> +// PR6451 - C++ Jump checking
> +struct X {
> + X();
> +};
> +
> +void test2() {
> + goto later; // expected-error {{illegal goto into protected scope}}
> + X x; // expected-note {{jump bypasses variable initialization}}
> +later:
> + ;
> +}
>
>
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