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Fix rethrowing the caught exception from streambuf #4372

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Merged
StephanTLavavej merged 2 commits into from
Feb 13, 2024
Merged

Fix rethrowing the caught exception from streambuf #4372

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f0d114a
Fix rethrowing the caught exception from streambuf
grcm10 Feb 7, 2024
8e68116
Code review feedback.
StephanTLavavej Feb 7, 2024
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6 changes: 4 additions & 2 deletions stl/inc/ostream
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Original file line number Diff line number Diff line change
Expand Up @@ -493,8 +493,10 @@ public:
_TRY_BEGIN
_Meta = _Traits::eq_int_type(_Traits::eof(), _Meta) ? _Strbuf->sgetc() : _Strbuf->snextc();
_CATCH_ALL
_Myios::setstate(ios_base::failbit);
_RERAISE;
// N4971 [ostream.inserters]/9: "If an exception was thrown
// while extracting a character, the function sets failbit in the error state,
// and if failbit is set in exceptions() the caught exception is rethrown."
_Myios::setstate(ios_base::failbit, _Myios::exceptions() == ios_base::failbit);
_CATCH_END

if (_Traits::eq_int_type(_Traits::eof(), _Meta)) {
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32 changes: 32 additions & 0 deletions tests/std/tests/GH_001858_iostream_exception/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,8 @@ struct test_exception {};
template <class CharT>
class throwing_buffer : public basic_streambuf<CharT> {
public:
using typename basic_streambuf<CharT>::int_type;

streampos seekoff(streamoff, ios_base::seekdir, ios_base::openmode = ios_base::in | ios_base::out) override {
throw test_exception{};
}
Expand All @@ -48,6 +50,10 @@ class throwing_buffer : public basic_streambuf<CharT> {
throw test_exception{};
}

int_type underflow() override {
throw test_exception{};
}

basic_streambuf<CharT>* to_buf() {
return this;
}
Expand Down Expand Up @@ -229,6 +235,32 @@ void test_ostream_exceptions() {
// Expected case
}
}

{ // operator<< (testing GH-4322 "<ostream>: Exception from streambuf should be caught and not rethrown")
basic_ostream<CharT> os(buffer.to_buf());

try {
os << &buffer;
} catch (const ios_base::failure&) {
assert(false);
} catch (const test_exception&) {
assert(false);
}
}

{ // operator<< rethrows the caught exception if failbit is set in exceptions()
basic_ostream<CharT> os(buffer.to_buf());
os.exceptions(ios_base::failbit);

try {
os << &buffer;
assert(false);
} catch (const ios_base::failure&) {
assert(false);
} catch (const test_exception&) {
// Expected case
}
}
}

// Also test strengthened and mandatory exception specifications.
Expand Down