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[flang][runtime] Don't always accept a bare exponent letter #151597

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Merged
merged 1 commit into from
Aug 5, 2025
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[flang][runtime] Don't always accept a bare exponent letter #151597

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13 changes: 11 additions & 2 deletions flang-rt/lib/runtime/edit-input.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -396,8 +396,9 @@ static RT_API_ATTRS ScannedRealInput ScanRealInput(
}
}
} else if (first == radixPointChar || (first >= '0' && first <= '9') ||
(bzMode && (first == ' ' || first == '\t')) || first == 'E' ||
first == 'D' || first == 'Q') {
(bzMode && (first == ' ' || first == '\t')) ||
(remaining.has_value() &&
(first == 'D' || first == 'E' || first == 'Q'))) {
if (first == '0') {
next = io.NextInField(remaining, edit);
if (next && (*next == 'x' || *next == 'X')) { // 0X...
Expand Down Expand Up @@ -462,6 +463,14 @@ static RT_API_ATTRS ScannedRealInput ScanRealInput(
// optional exponent letter and the exponent value.
io.SkipSpaces(remaining);
next = io.NextInField(remaining, edit);
if (!next) {
if (remaining.has_value()) {
// bare exponent letter accepted in fixed-width field
hasGoodExponent = true;
} else {
return {}; // error
}
}
}
}
if (next &&
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9 changes: 6 additions & 3 deletions flang-rt/unittests/Runtime/NumericalFormatTest.cpp
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Expand Up @@ -965,7 +965,10 @@ TEST(IOApiTests, EditDoubleInputValues) {
{"(RU,E9.1)", " 1.0E-325", 0x1, 0},
{"(E9.1)", "-1.0E-325", 0x8000000000000000, 0},
{"(RD,E9.1)", "-1.0E-325", 0x8000000000000001, 0},
{"(F7.0))", "+NaN(q)", 0x7ff8000000000000, 0},
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@akuhlens akuhlens Aug 4, 2025

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Good Catch!

{"(F7.0)", "+NaN(q)", 0x7ff8000000000000, 0},
{"(G)", "D", 0, IostatBadRealInput},
{"(G0)", "D", 0, IostatErrorInFormat},
{"(G1.0)", "D", 0, 0},
};
for (auto const &[format, data, want, iostat] : testCases) {
auto cookie{IONAME(BeginInternalFormattedInput)(
Expand All @@ -988,13 +991,13 @@ TEST(IOApiTests, EditDoubleInputValues) {
// union value
IONAME(GetIoMsg)(cookie, iomsg, bufferSize - 1);
auto status{IONAME(EndIoStatement)(cookie)};
ASSERT_EQ(status, iostat)
EXPECT_EQ(status, iostat)
<< '\'' << format << "' failed reading '" << data << "', status "
<< static_cast<int>(status) << " != expected " << iostat << " iomsg '"
<< iomsg << "'";

// Ensure raw uint64 value matches expected conversion from double
ASSERT_EQ(u.raw, want) << '\'' << format << "' failed reading '" << data
EXPECT_EQ(u.raw, want) << '\'' << format << "' failed reading '" << data
<< "', want " << want << ", got " << u.raw;
}
}
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5 changes: 4 additions & 1 deletion flang/docs/Extensions.md
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Expand Up @@ -479,6 +479,9 @@ end
* Old-style `PARAMETER pi=3.14` statement without parentheses
[-falternative-parameter-statement]
* `UNSIGNED` type (-funsigned)
* Default exponent of zero, e.g. `3.14159E`, on a READ from a
fixed-width input field. Includes the case with only an
exponent letter for compatibility with other compilers.

### Extensions and legacy features deliberately not supported

Expand All @@ -492,7 +495,7 @@ end
* `VIRTUAL` as synonym for `DIMENSION`
* `ENCODE` and `DECODE` as synonyms for internal I/O
* `IMPLICIT AUTOMATIC`, `IMPLICIT STATIC`
* Default exponent of zero, e.g. `3.14159E`
* Default exponent of zero, e.g. `3.14159E`, on a literal constant
* Characters in defined operators that are neither letters nor digits
* `B` suffix on unquoted octal constants
* `Z` prefix on unquoted hexadecimal constants (dangerous)
Expand Down
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