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[C++20] [Modules] Exit early if export decl is not valid 

This patch fixes a crash due to following simple program:
> export struct Unit {
>    bool operator<(const Unit&);
> };

It would crash since the compiler would set the module ownership for
Unit. And the declaration with a module ownership is assumed to own a
module. But here isn't one. So here is the crash.

This patch fixes this by exiting early if it finds the export decl is
already invalid.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D117093
This commit is contained in:
Chuanqi Xu 2022-01-14 10:21:42 +08:00
parent b8367518e7
commit 4f8916cfdd
2 changed files with 16 additions and 3 deletions
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15
clang/lib/Sema/SemaModule.cpp
View File

@ -527,21 +527,30 @@ Decl *Sema::ActOnStartExportDecl(Scope *S, SourceLocation ExportLoc,
// Set this temporarily so we know the export-declaration was braced.
D->setRBraceLoc(LBraceLoc);
CurContext->addDecl(D);
PushDeclContext(S, D);
// C++2a [module.interface]p1:
// An export-declaration shall appear only [...] in the purview of a module
// interface unit. An export-declaration shall not appear directly or
// indirectly within [...] a private-module-fragment.
if (ModuleScopes.empty() || !ModuleScopes.back().Module->isModulePurview()) {
Diag(ExportLoc, diag::err_export_not_in_module_interface) << 0;
D->setInvalidDecl();
return D;
} else if (!ModuleScopes.back().ModuleInterface) {
Diag(ExportLoc, diag::err_export_not_in_module_interface) << 1;
Diag(ModuleScopes.back().BeginLoc,
diag::note_not_module_interface_add_export)
<< FixItHint::CreateInsertion(ModuleScopes.back().BeginLoc, "export ");
D->setInvalidDecl();
return D;
} else if (ModuleScopes.back().Module->Kind ==
Module::PrivateModuleFragment) {
Diag(ExportLoc, diag::err_export_in_private_module_fragment);
Diag(ModuleScopes.back().BeginLoc, diag::note_private_module_fragment);
D->setInvalidDecl();
return D;
}
for (const DeclContext *DC = CurContext; DC; DC = DC->getLexicalParent()) {
@ -553,7 +562,7 @@ Decl *Sema::ActOnStartExportDecl(Scope *S, SourceLocation ExportLoc,
Diag(ND->getLocation(), diag::note_anonymous_namespace);
// Don't diagnose internal-linkage declarations in this region.
D->setInvalidDecl();
break;
return D;
}
// A declaration is exported if it is [...] a namespace-definition
@ -572,10 +581,10 @@ Decl *Sema::ActOnStartExportDecl(Scope *S, SourceLocation ExportLoc,
Diag(ExportLoc, diag::err_export_within_export);
if (ED->hasBraces())
Diag(ED->getLocation(), diag::note_export);
D->setInvalidDecl();
return D;
}
CurContext->addDecl(D);
PushDeclContext(S, D);
D->setModuleOwnershipKind(Decl::ModuleOwnershipKind::VisibleWhenImported);
return D;
}

4
clang/test/Modules/export-in-non-modules.cpp Normal file
View File

@ -0,0 +1,4 @@
// RUN: %clang_cc1 -std=c++20 %s -fsyntax-only -verify
export struct Unit { // expected-error {{export declaration can only be used within a module interface unit after the module declaration}}
bool operator<(const Unit &);
};