arphaman created this revision.
arphaman added a reviewer: rsmith.
arphaman added a subscriber: cfe-commits.
arphaman set the repository for this revision to rL LLVM.
This patch fixes a bug that's tracked by PR 10758 and duplicates like PR 30343.
The bug causes clang to crash with a stack overflow while recursing infinitely
trying to perform copy-initialization on a type without a copy constructor but
with a constructor that accepts another type that can be constructed using the
original type. This example shows the structures and code that causes this
behavior:
```
struct Bar;
struct Foo {
Foo(Bar);
};
struct Bar {
Bar(const Foo&);
Bar(Bar&);
};
Foo foo(const Bar &b) {
return b;
}
```
The patch fixes this bug by detecting the recursive behavior and failing
correctly with an appropriate error message. It also tries to provide a
meaningful diagnostic note about the constructor which leads to this behavior,
like in the example shown below:
```
foo.cpp:6:3: note: candidate constructor not viable: no known conversion from
'const Bar' to 'const Foo &' for 1st argument
Bar(const Foo&);
^
```
Repository:
rL LLVM
https://reviews.llvm.org/D25051
Files:
include/clang/Sema/Sema.h
lib/Sema/SemaInit.cpp
test/SemaCXX/constructor-initializer.cpp
Index: test/SemaCXX/constructor-initializer.cpp
===================================================================
--- test/SemaCXX/constructor-initializer.cpp
+++ test/SemaCXX/constructor-initializer.cpp
@@ -302,3 +302,22 @@
struct S2 { union { union { int n; }; char c; }; S2() : n(n) {} }; //
expected-warning {{field 'n' is uninitialized when used here}}
struct S3 { struct { int n; }; S3() : n(n) {} }; // expected-warning
{{field 'n' is uninitialized when used here}}
}
+
+namespace PR10758 {
+struct A;
+struct B {
+ B (A const &); // expected-note 2 {{candidate constructor not viable: no
known conversion from 'const PR10758::B' to 'const PR10758::A &' for 1st
argument}}
+ B (B &); // expected-note 2 {{candidate constructor not viable: 1st argument
('const PR10758::B') would lose const qualifier}}
+};
+struct A {
+ A (B); // expected-note 2 {{passing argument to parameter here}}
+};
+
+B f(B const &b) {
+ return b; // expected-error {{no matching constructor for initialization of
'PR10758::B'}}
+}
+
+A f2(const B &b) {
+ return b; // expected-error {{no matching constructor for initialization of
'PR10758::B'}}
+}
+}
Index: lib/Sema/SemaInit.cpp
===================================================================
--- lib/Sema/SemaInit.cpp
+++ lib/Sema/SemaInit.cpp
@@ -7932,7 +7932,47 @@
AllowExplicit);
InitializationSequence Seq(*this, Entity, Kind, InitE, TopLevelOfInitList);
+ // Fix for PR 10758: Prevent infinite recursion when performing parameter
+ // copy-initialization.
+ const bool ShouldTrackCopy =
+ Entity.isParameterKind() && Seq.isConstructorInitialization();
+ if (ShouldTrackCopy) {
+ if (llvm::find(CurrentParameterCopyTypes, Entity.getType()) !=
+ CurrentParameterCopyTypes.end()) {
+ Seq.SetOverloadFailure(
+ InitializationSequence::FK_ConstructorOverloadFailed,
+ OR_No_Viable_Function);
+
+ // Try to give a meaningful diagnostic note for the problematic
+ // constructor.
+ const auto LastStep = Seq.step_end() - 1;
+ assert(LastStep->Kind ==
+ InitializationSequence::SK_ConstructorInitialization);
+ const FunctionDecl *Function = LastStep->Function.Function;
+ auto Candidate =
+ llvm::find_if(Seq.getFailedCandidateSet(),
+ [Function](const OverloadCandidate &Candidate) -> bool
{
+ return Candidate.Viable &&
+ Candidate.Function == Function &&
+ Candidate.NumConversions > 0;
+ });
+ if (Candidate != Seq.getFailedCandidateSet().end() &&
+ Function->getNumParams() > 0) {
+ Candidate->Viable = false;
+ Candidate->FailureKind = ovl_fail_bad_conversion;
+ Candidate->Conversions[0].setBad(BadConversionSequence::no_conversion,
+ InitE,
+ Function->getParamDecl(0)->getType());
+ }
+ }
+ CurrentParameterCopyTypes.push_back(Entity.getType());
+ }
+
ExprResult Result = Seq.Perform(*this, Entity, Kind, InitE);
+ if (ShouldTrackCopy) {
+ CurrentParameterCopyTypes.pop_back();
+ }
+
return Result;
}
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -1023,6 +1023,10 @@
/// same special member, we should act as if it is not yet declared.
llvm::SmallSet<SpecialMemberDecl, 4> SpecialMembersBeingDeclared;
+ /// Stack of types that correspond to the parameter entities that are
+ /// currently being copy-initialized. Can be empty.
+ llvm::SmallVector<QualType, 4> CurrentParameterCopyTypes;
+
void ReadMethodPool(Selector Sel);
void updateOutOfDateSelector(Selector Sel);
Index: test/SemaCXX/constructor-initializer.cpp
===================================================================
--- test/SemaCXX/constructor-initializer.cpp
+++ test/SemaCXX/constructor-initializer.cpp
@@ -302,3 +302,22 @@
struct S2 { union { union { int n; }; char c; }; S2() : n(n) {} }; // expected-warning {{field 'n' is uninitialized when used here}}
struct S3 { struct { int n; }; S3() : n(n) {} }; // expected-warning {{field 'n' is uninitialized when used here}}
}
+
+namespace PR10758 {
+struct A;
+struct B {
+ B (A const &); // expected-note 2 {{candidate constructor not viable: no known conversion from 'const PR10758::B' to 'const PR10758::A &' for 1st argument}}
+ B (B &); // expected-note 2 {{candidate constructor not viable: 1st argument ('const PR10758::B') would lose const qualifier}}
+};
+struct A {
+ A (B); // expected-note 2 {{passing argument to parameter here}}
+};
+
+B f(B const &b) {
+ return b; // expected-error {{no matching constructor for initialization of 'PR10758::B'}}
+}
+
+A f2(const B &b) {
+ return b; // expected-error {{no matching constructor for initialization of 'PR10758::B'}}
+}
+}
Index: lib/Sema/SemaInit.cpp
===================================================================
--- lib/Sema/SemaInit.cpp
+++ lib/Sema/SemaInit.cpp
@@ -7932,7 +7932,47 @@
AllowExplicit);
InitializationSequence Seq(*this, Entity, Kind, InitE, TopLevelOfInitList);
+ // Fix for PR 10758: Prevent infinite recursion when performing parameter
+ // copy-initialization.
+ const bool ShouldTrackCopy =
+ Entity.isParameterKind() && Seq.isConstructorInitialization();
+ if (ShouldTrackCopy) {
+ if (llvm::find(CurrentParameterCopyTypes, Entity.getType()) !=
+ CurrentParameterCopyTypes.end()) {
+ Seq.SetOverloadFailure(
+ InitializationSequence::FK_ConstructorOverloadFailed,
+ OR_No_Viable_Function);
+
+ // Try to give a meaningful diagnostic note for the problematic
+ // constructor.
+ const auto LastStep = Seq.step_end() - 1;
+ assert(LastStep->Kind ==
+ InitializationSequence::SK_ConstructorInitialization);
+ const FunctionDecl *Function = LastStep->Function.Function;
+ auto Candidate =
+ llvm::find_if(Seq.getFailedCandidateSet(),
+ [Function](const OverloadCandidate &Candidate) -> bool {
+ return Candidate.Viable &&
+ Candidate.Function == Function &&
+ Candidate.NumConversions > 0;
+ });
+ if (Candidate != Seq.getFailedCandidateSet().end() &&
+ Function->getNumParams() > 0) {
+ Candidate->Viable = false;
+ Candidate->FailureKind = ovl_fail_bad_conversion;
+ Candidate->Conversions[0].setBad(BadConversionSequence::no_conversion,
+ InitE,
+ Function->getParamDecl(0)->getType());
+ }
+ }
+ CurrentParameterCopyTypes.push_back(Entity.getType());
+ }
+
ExprResult Result = Seq.Perform(*this, Entity, Kind, InitE);
+ if (ShouldTrackCopy) {
+ CurrentParameterCopyTypes.pop_back();
+ }
+
return Result;
}
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -1023,6 +1023,10 @@
/// same special member, we should act as if it is not yet declared.
llvm::SmallSet<SpecialMemberDecl, 4> SpecialMembersBeingDeclared;
+ /// Stack of types that correspond to the parameter entities that are
+ /// currently being copy-initialized. Can be empty.
+ llvm::SmallVector<QualType, 4> CurrentParameterCopyTypes;
+
void ReadMethodPool(Selector Sel);
void updateOutOfDateSelector(Selector Sel);
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
