[flang][runtime] Complete list-directed character input with DECIMAL='COMMA'

Most of the infrastructure for DECIMAL='COMMA' mode was in place
in the I/O runtime support library, but I dropped the ba

[flang][runtime] Complete list-directed character input with DECIMAL='COMMA'

Most of the infrastructure for DECIMAL='COMMA' mode was in place
in the I/O runtime support library, but I dropped the ball for
list-directed character input, which has its own detection of
input separators. Finish the job.

Differential Revision: https://reviews.llvm.org/D129679

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[flang] Fix typo in runtime message

The title says it.

Differential Revision: https://reviews.llvm.org/D129329

[flang][runtime] Respect PAD='NO' on READ/WRITE

The check for the PAD= setting should examine the mutable modes
of the current I/O statement, not the persistent modes of the
I/O unit.

Differential

[flang][runtime] Respect PAD='NO' on READ/WRITE

The check for the PAD= setting should examine the mutable modes
of the current I/O statement, not the persistent modes of the
I/O unit.

Differential Revision: https://reviews.llvm.org/D128389

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[flang][runtime] Allow recovery from BACKSPACE(badUnit)

When an unconnected unit number is used in a BACKSPACE statement
with ERR=, IOSTAT=, &/or IOMSG= control specifiers, don't crash,
but let the

[flang][runtime] Allow recovery from BACKSPACE(badUnit)

When an unconnected unit number is used in a BACKSPACE statement
with ERR=, IOSTAT=, &/or IOMSG= control specifiers, don't crash,
but let the program deal with the error.

Differential Revision: https://reviews.llvm.org/D127782

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[flang][runtime] Skip remainder of bad input record even with ADVANCE='NO'

After a recoverable error condition in a READ statement with ADVANCE='NO',
skip the remainder of the current record.

Diffe

[flang][runtime] Skip remainder of bad input record even with ADVANCE='NO'

After a recoverable error condition in a READ statement with ADVANCE='NO',
skip the remainder of the current record.

Differential Revision: https://reviews.llvm.org/D127433

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[flang][runtime] Fix list-directed/NAMELIST complex input with "r*" repetition count

The little state machine in GetNextDataEdit() wasn't transitioning
properly from reading the imaginary part of th

[flang][runtime] Fix list-directed/NAMELIST complex input with "r*" repetition count

The little state machine in GetNextDataEdit() wasn't transitioning
properly from reading the imaginary part of the number back to the
real part for the next iteration of a repeated value.

Differential Revision: https://reviews.llvm.org/D127422

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[flang][runtime] Better (but still synchronous) support for asynchronous I/O

Track pending "asynchronous" I/O operation IDs so that WAIT statements can
report errors about bad ID numbers.

Lowering

[flang][runtime] Better (but still synchronous) support for asynchronous I/O

Track pending "asynchronous" I/O operation IDs so that WAIT statements can
report errors about bad ID numbers.

Lowering will need to extended to call GetAsynchronousId() for a READ or
WRITE statement with ID=n.

Differential Revision: https://reviews.llvm.org/D127421

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[flang][runtime] Fix nonadvancing output edge case

When nonadvancing output uses T/TL control edit descriptors to reposition
the record, don't reset the position to the furthest point written at
the

[flang][runtime] Fix nonadvancing output edge case

When nonadvancing output uses T/TL control edit descriptors to reposition
the record, don't reset the position to the furthest point written at
the end of the write.

Differential Revision: https://reviews.llvm.org/D127420

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[flang][runtime] Fix deadlock in error recovery

When an external I/O statement is in a recoverable error
state before any data transfers take place (for example,
an unformatted transfer with ERR=/IO

[flang][runtime] Fix deadlock in error recovery

When an external I/O statement is in a recoverable error
state before any data transfers take place (for example,
an unformatted transfer with ERR=/IOSTAT=/IOMSG= attempted on
a formatted unit), ensure that the unit's mutex is still
released at the end of the statement.

Differential Revision: https://reviews.llvm.org/D127032

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[flang][runtime] INQUIRE(FILE="...",SIZE=nbytes)

Implement inquire-by-file SIZE= specifier.

Differential Revision: https://reviews.llvm.org/D127014

[flang][runtime] INQUIRE(UNIT=666,NUMBER=n) must set n=666

Whether a unit number in an inquire-by-unit statement is valid or not,
it should be the value to which the NUMBER= variable is set, not -1.

[flang][runtime] INQUIRE(UNIT=666,NUMBER=n) must set n=666

Whether a unit number in an inquire-by-unit statement is valid or not,
it should be the value to which the NUMBER= variable is set, not -1.
-1 should be returned to NUMBER= only for an inquire-by-file statement
when the FILE= is not connected to any unit.

Differential Revision: https://reviews.llvm.org/D126145

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[flang][runtime] BACKSPACE after non-advancing I/O

A BACKSPACE statement on a unit after a READ or WRITE with ADVANCE="NO"
must reset the position to the beginning of the record, not to the
beginnin

[flang][runtime] BACKSPACE after non-advancing I/O

A BACKSPACE statement on a unit after a READ or WRITE with ADVANCE="NO"
must reset the position to the beginning of the record, not to the
beginning of the previous one.

Differential Revision: https://reviews.llvm.org/D125057

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[flang][runtime] Correct emission & reading of unterminated final records

When the last operation on a foramtted sequential or stream file (prior
to an implied or explicit ENDFILE) is a non-advancin

[flang][runtime] Correct emission & reading of unterminated final records

When the last operation on a foramtted sequential or stream file (prior
to an implied or explicit ENDFILE) is a non-advancing WRITE, ensure
that any partial record data is emitted to the file without a line
terminator. Further, when that last record is read with a non-advancing
READ, ensure that it won't raise an end-of-record condition after its
data, but instead will signal an end-of-file.

Differential Revision: https://reviews.llvm.org/D124546

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[flang][runtime] Signal record read overrun when PAD='NO'

When PAD='NO' and ADVANCE='YES', we currently signal an input
error when a formatted read tries to go past the end of a record
only when a f

[flang][runtime] Signal record read overrun when PAD='NO'

When PAD='NO' and ADVANCE='YES', we currently signal an input
error when a formatted read tries to go past the end of a record
only when a fixed RECL= is in effect. Other compilers will signal
an error without RECL= too, and that seems like a precedent we
should follow.

Differential Revision: https://reviews.llvm.org/D124301

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[flang] Add & use a better visit() (take 2)

Adds flang/include/flang/Common/log2-visit.h, which defines
a Fortran::common::visit() template function that is a drop-in
replacement for std::visit().

[flang] Add & use a better visit() (take 2)

Adds flang/include/flang/Common/log2-visit.h, which defines
a Fortran::common::visit() template function that is a drop-in
replacement for std::visit(). Modifies most use sites in
the front-end and runtime to use common::visit().

The C++ standard mandates that std::visit() have O(1) execution
time, which forces implementations to build dispatch tables.
This new common::visit() is O(log2 N) in the number of alternatives
in a variant<>, but that N tends to be small and so this change
produces a fairly significant improvement in compiler build
memory requirements, a 5-10% improvement in compiler build time,
and a small improvement in compiler execution time.

Building with -DFLANG_USE_STD_VISIT causes common::visit()
to be an alias for std::visit().

Calls to common::visit() with multiple variant arguments
are referred to std::visit(), pending further work.

This change is enabled only for GCC builds with GCC >= 9;
an earlier attempt (D122441) ran into bugs in some versions of
clang and was reverted rather than simply disabled; and it is
not well tested with MSVC. In non-GCC and older GCC builds,
common::visit() is simply an alias for std::visit().

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[flang][runtime] Preserve effect of positioning in record in non-advancing output

When formatted non-advancing output ends in a control edit descriptor
like nX or Tn or TRn that effectively extends

[flang][runtime] Preserve effect of positioning in record in non-advancing output

When formatted non-advancing output ends in a control edit descriptor
like nX or Tn or TRn that effectively extends the record, fill any
gap with explicit blanks at the completion of the WRITE.

Differential Revision: https://reviews.llvm.org/D123716

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[flang] Always encode multi-byte output in UTF-8

A recent change to implement UTF-8 encoding should have
made the encoding conditional only for CHARACTER(KIND=1)
to enable UTF-8 output vs. Latin-1 o

[flang] Always encode multi-byte output in UTF-8

A recent change to implement UTF-8 encoding should have
made the encoding conditional only for CHARACTER(KIND=1)
to enable UTF-8 output vs. Latin-1 or whatever. UTF-8 output
of wider CHARACTER kinds should not be conditional (until we choose
to support UCS-16, maybe). So wider CHARACTER kinds are being
emitted with extra zero bytes; this patch fixes them.

Differential Revision: https://reviews.llvm.org/D123711

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[flang] Respect left tab limit with Tn editing after ADVANCE='NO'

Correct the implementation of non-advancing I/O after some testing
to ensure that T tab edit descriptors are not allowed to back up

[flang] Respect left tab limit with Tn editing after ADVANCE='NO'

Correct the implementation of non-advancing I/O after some testing
to ensure that T tab edit descriptors are not allowed to back up
into positions of a record prior to where it stood at the beginning
of the I/O statement.

Differential Revision: https://reviews.llvm.org/D123709

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Revert "[flang] Add & use a better visit()"

This reverts commit 2ab9990c9eb79682a4d4b183dfbc7612d3e55328. It has
caused multiple build failures:
* https://lab.llvm.org/buildbot/#/builders/177/build

Revert "[flang] Add & use a better visit()"

This reverts commit 2ab9990c9eb79682a4d4b183dfbc7612d3e55328. It has
caused multiple build failures:
* https://lab.llvm.org/buildbot/#/builders/177/builds/4346
* https://lab.llvm.org/buildbot/#/builders/180/builds/3803
* https://lab.llvm.org/buildbot/#/builders/175/builds/10419
* https://lab.llvm.org/buildbot/#/builders/191/builds/4318
* https://lab.llvm.org/buildbot/#/builders/173/builds/4274
* https://lab.llvm.org/buildbot/#/builders/181/builds/4297

All these bots failed with a time-out:
```
command timed out: 1200 seconds without output running [b'ninja', b'-j', b'32'], attempting to kill
```
I'm guessing that that's due to template instantiations failing at some
point (https://reviews.llvm.org/D122441 introduced a custom
implementation of std::visit). Everything seems fine when either:
* building on X86 with GCC or Clang (tested with GCC 9.3 and Clang 12)
* building on AArch64 with GCC (tested with GCC 11)

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[flang] Catch bad OPEN(STATUS=) cases

STATUS='NEW' and 'REPLACE' require FILE= to be present.
STATUS='SCRATCH' may not appear with FILE=.

These errors are caught at compilation time when constant c

[flang] Catch bad OPEN(STATUS=) cases

STATUS='NEW' and 'REPLACE' require FILE= to be present.
STATUS='SCRATCH' may not appear with FILE=.

These errors are caught at compilation time when constant character
strings are used in an OPEN statement, but the runtime needs
to enforce them as well to catch errors in OPEN statements
with character variables and expressions.

Differential Revision: https://reviews.llvm.org/D122509

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[flang] Add & use a better visit()

Adds flang/include/flang/Common/visit.h, which defines
a Fortran::common::visit() template function that is a drop-in
replacement for std::visit(). Modifies most

[flang] Add & use a better visit()

Adds flang/include/flang/Common/visit.h, which defines
a Fortran::common::visit() template function that is a drop-in
replacement for std::visit(). Modifies most use sites in
the front-end and runtime to use common::visit().

The C++ standard mandates that std::visit() have O(1) execution
time, which forces implementations to build dispatch tables.
This new common::visit() is O(log2 N) in the number of alternatives
in a variant<>, but that N tends to be small and so this change
produces a fairly significant improvement in compiler build
memory requirements, a 5-10% improvement in compiler build time,
and a small improvement in compiler execution time.

Building with -DFLANG_USE_STD_VISIT causes common::visit()
to be an alias for std::visit().

Calls to common::visit() with multiple variant arguments
are referred to std::visit(), pending further work.

Differential Revision: https://reviews.llvm.org/D122441

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[flang] Initial UTF-8 support in runtime I/O

Implements UTF-8 encoding and decoding for external units
with OPEN(ENCODING='UTF-8'). This encoding applies to default
CHARACTER values that are not 7-

[flang] Initial UTF-8 support in runtime I/O

Implements UTF-8 encoding and decoding for external units
with OPEN(ENCODING='UTF-8'). This encoding applies to default
CHARACTER values that are not 7-bit ASCII as well as to
the wide CHARACTER kinds 2 and 4. Basic testing is in place
via direct calls to the runtime I/O APIs, but serious checkout
awaits lowering support of the wide CHARACTER kinds.

Differential Revision: https://reviews.llvm.org/D122038

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[flang] Error recovery improvement in runtime (IOMSG=)

Some refactoring and related fixes for more accurate
user program error recovery in the I/O runtime, especially
for error recovery with IOMSG=

[flang] Error recovery improvement in runtime (IOMSG=)

Some refactoring and related fixes for more accurate
user program error recovery in the I/O runtime, especially
for error recovery with IOMSG= character values.

1) Move any work in an EndIoStatement() implementation
that may raise an error into a new CompleteOperation()
member function. This allows error handling APIs like
GetIoMsg() to complete a pending I/O statement and harvest
any errors that may result.

2) Move the pending error code from ErroneousIoStatementState
to a new pendingError_ data member in IoErrorHandler.
This allows IoErrorHandler::InError() to return a correct
result when there is a pending error that will be recovered
from so that I/O list data transfers don't crash in the meantime.

3) Don't create and leak a unit for a failed OPEN(NEWUNIT=n)
with error recovery, and don't modify 'n'. (Depends on
changes to API call ordering in lowering, in a separate patch;
code was added to ensure that OPEN statement control list
specifiers, e.g. SetFile(), must be passed before GetNewUnit().)

4) Fix the code that calls a form of strerror to fill an
IOMSG= variable so that it actually works for Fortran's
character type: blank fill with no null or newline termination.

Differential Revision: https://reviews.llvm.org/D122036

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[flang] Improve runtime crash messages

Where possible, I added additional information to the messages to help
programmers figure out what went wrong. I also removed all uses of the word
"bad" from

[flang] Improve runtime crash messages

Where possible, I added additional information to the messages to help
programmers figure out what went wrong. I also removed all uses of the word
"bad" from the messages since (to me) that implies a moral judgement rather
than a programming error. I replaced it with either "invalid" or "unsupported"
where appropriate.

Differential Revision: https://reviews.llvm.org/D121493

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[flang] Use faster path for default formatted character input

Rather than reading default character variables in formatted
input one byte at a time via NextInField(), skip and read
them via blocks o

[flang] Use faster path for default formatted character input

Rather than reading default character variables in formatted
input one byte at a time via NextInField(), skip and read
them via blocks of available buffer data. This eliminates
a bottleneck that affected reads of large character values.
(It also exposed a problem with sequential reads with RECL=
set on the OPEN statement, so that's fixed too.)

Differential Revision: https://reviews.llvm.org/D121144

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