On Wed, Mar 7, 2018 at 1:55 PM, Reid Kleckner via cfe-commits < cfe-commits@lists.llvm.org> wrote:
> Author: rnk > Date: Wed Mar 7 10:55:10 2018 > New Revision: 326926 > > URL: http://llvm.org/viewvc/llvm-project?rev=326926&view=rev > Log: > Push a function scope when parsing function bodies without a declaration > > Summary: > This is PR36536. > > There are a few ways to reach Sema::ActOnStartOfFunctionDef with a null > Decl. Currently, the parser continues on to attempt to parse the > statements in the function body without pushing a function scope or > declaration context. However, lots of statement parsing logic relies on > getCurFunction() returning something reasonable. It turns out that > getCurFunction() will never return null today because of an optimization > where Sema pre-allocates one FunctionScopeInfo and reuses it when > possible. This goes wrong when something inside the function body causes > us to push another function scope, such as requiring an implicit > definition of a special member function. Reusing the state clears it > out, which will lead to bugs. In PR36536, we found that the SwitchStack > gets unbalanced, because we push a switch, clear out the stack, and then > try to pop a switch that isn't there. > > As a follow-up, I plan to move the pre-allocated FunctionScopeInfo out > of the FunctionScopes stack. This means the FunctionScopes stack will > often be empty, and callers of getCurFunction() will need to check for > null. > > Reviewers: thakis > > Subscribers: cfe-commits > > Differential Revision: https://reviews.llvm.org/D43980 > > Added: > cfe/trunk/test/SemaCXX/pr36536.cpp > Modified: > cfe/trunk/lib/Sema/SemaDecl.cpp > > Modified: cfe/trunk/lib/Sema/SemaDecl.cpp > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/ > SemaDecl.cpp?rev=326926&r1=326925&r2=326926&view=diff > ============================================================ > ================== > --- cfe/trunk/lib/Sema/SemaDecl.cpp (original) > +++ cfe/trunk/lib/Sema/SemaDecl.cpp Wed Mar 7 10:55:10 2018 > @@ -12406,8 +12406,13 @@ static void RebuildLambdaScopeInfo(CXXMe > > Decl *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Decl *D, > SkipBodyInfo *SkipBody) { > - if (!D) > + if (!D) { > + // Parsing the function declaration failed in some way. Push on a > fake scope > + // anyway so we can try to parse the function body. > + PushFunctionScope(); > return D; > + } > + > FunctionDecl *FD = nullptr; > > if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D)) > @@ -12816,6 +12821,9 @@ Decl *Sema::ActOnFinishFunctionBody(Decl > getCurFunction()->ObjCWarnForNoInitDelegation = false; > } > } else { > + // Parsing the function declaration failed in some way. Pop the fake > scope > + // we pushed on. > + PopFunctionScopeInfo(ActivePolicy, dcl); > return nullptr; > } > > > Added: cfe/trunk/test/SemaCXX/pr36536.cpp > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/ > SemaCXX/pr36536.cpp?rev=326926&view=auto > ============================================================ > ================== > --- cfe/trunk/test/SemaCXX/pr36536.cpp (added) > +++ cfe/trunk/test/SemaCXX/pr36536.cpp Wed Mar 7 10:55:10 2018 > @@ -0,0 +1,44 @@ > +// RUN: %clang_cc1 -std=c++11 %s -verify -fno-spell-checking > + > +// These test cases are constructed to make clang call > ActOnStartOfFunctionDef > +// with nullptr. > + > +struct ImplicitDefaultCtor1 {}; > +struct Foo { > + typedef int NameInClass; > + void f(); > +}; > +namespace bar { > +// FIXME: Improved our recovery to make this a redeclaration of Foo::f, > (nit: s/Improved/Improve/) > +// even though this is in the wrong namespace. That will allow name > lookup to > +// find NameInClass below. Users are likely to hit this when they forget > to > +// close namespaces. > +// expected-error@+1 {{cannot define or redeclare 'f' here}} > +void Foo::f() { > + switch (0) { case 0: ImplicitDefaultCtor1 o; } > + // expected-error@+1 {{unknown type name 'NameInClass'}} > + NameInClass var; > +} > +} // namespace bar > + > +struct ImplicitDefaultCtor2 {}; > +template <typename T> class TFoo { void f(); }; > +// expected-error@+1 {{nested name specifier 'decltype(TFoo<T>())::'}} > +template <typename T> void decltype(TFoo<T>())::f() { > + switch (0) { case 0: ImplicitDefaultCtor1 o; } > +} > + > +namespace tpl2 { > +struct ImplicitDefaultCtor3 {}; > +template <class T1> class A { > + template <class T2> class B { > + void mf2(); > + }; > +}; > +template <class Y> > +template <> > +// expected-error@+1 {{nested name specifier 'A<Y>::B<double>::'}} > +void A<Y>::B<double>::mf2() { > + switch (0) { case 0: ImplicitDefaultCtor3 o; } > +} > +} > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >
_______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
