[flang] Allow restricted specific intrinsic functions as implicitly-interfaced procedure pointer targets

The predicate "CanBeCalledViaImplicitInterface()" was returning false for
restricted specific

[flang] Allow restricted specific intrinsic functions as implicitly-interfaced procedure pointer targets

The predicate "CanBeCalledViaImplicitInterface()" was returning false for
restricted specific intrinsic functions (e.g., SIN) because their procedure
characteristics have the elemental attribute; this leads to a bogus semantic
error when one attempts to use them as proc-targets in procedure pointer
assignment statements when the left-hand side of the assignment is a procedure
pointer with an implicit interface. However, these restricted specific intrinsic
functions have always been allowed as special cases for such usage -- it is
as if they are elemental when it is necessary for them to be so, but not
when it's a problem.

Differential Revision: https://reviews.llvm.org/D130386

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[flang] Better error message for NULL() actual argument for dummy allocatable

f18 intentionally does not support the spottily-implemented language extension
in which one can pass NULL() for an alloc

[flang] Better error message for NULL() actual argument for dummy allocatable

f18 intentionally does not support the spottily-implemented language extension
in which one can pass NULL() for an allocatable dummy argument. This is perhaps
a sanctioned side effect in other compilers of the fact that they pass distinct
"base address" and "descriptor address" physical arguments.

Make the error message in this case more specific to the circumstances, and
add a note to Extensions.md to clarify that this behavior is intended.

(We could, with some effort in lowering, support passing NULL for an INTENT(IN)
allocatable dummy, but let's see whether such nonconforming usage appears
in a real application before spending any more time on it.)

Differential Revision: https://reviews.llvm.org/D130380

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[flang] Refine semantic checks for procedure pointer assignment

Some procedure pointers and EXTERNAL procedures have neither
explicit interfaces nor result types; these procedures are obviously
not

[flang] Refine semantic checks for procedure pointer assignment

Some procedure pointers and EXTERNAL procedures have neither
explicit interfaces nor result types; these procedures are obviously
not known to be functions, but they could be, so semantics must not
assume that they are necessarily subroutines. Refine the procedure
pointer / dummy procedure compatibility check to handle these more
ambiguous cases and not elicit inappropriate error messages.

Differential Revision: https://reviews.llvm.org/D129674

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[nfc][flang] Fix spelling errors and usage in an error message

Differential Revision: https://reviews.llvm.org/D126490

[flang] Extension: Accept Hollerith actual arguments as if they were BOZ

When a Hollerith (or short character) literal is presented as an actual
argument that corresponds to a dummy argument for whi

[flang] Extension: Accept Hollerith actual arguments as if they were BOZ

When a Hollerith (or short character) literal is presented as an actual
argument that corresponds to a dummy argument for which a BOZ literal
would be acceptable, treat the Hollerith as if it had been a BOZ
literal in the same way -- and with the same code -- as f18 already
does for the similar extension in DATA statements.

Differential Revision: https://reviews.llvm.org/D126144

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[flang] Add one semantic check for elemental call arguments

As Fortran 2018 15.8.1(3), in a reference to an elemental procedure, if
any argument is an array, each actual argument that corresponds to

[flang] Add one semantic check for elemental call arguments

As Fortran 2018 15.8.1(3), in a reference to an elemental procedure, if
any argument is an array, each actual argument that corresponds to an
INTENT (OUT) or INTENT (INOUT) dummy argument shall be an array. Add
this semantic check.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D125685

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[flang] Allow NULL() actual argument for optional dummy procedure

A disassociated procedure pointer is allowed to be passed as an absent
actual argument that corresponds to an optional dummy procedu

[flang] Allow NULL() actual argument for optional dummy procedure

A disassociated procedure pointer is allowed to be passed as an absent
actual argument that corresponds to an optional dummy procedure,
but not NULL(); accept that case as well.

Differential Revision: https://reviews.llvm.org/D125127

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[flang] Refine handling of short character actual arguments

Actual arguments whose lengths are less than the expected length
of their corresponding dummy argument are errors; but this needs
to be re

[flang] Refine handling of short character actual arguments

Actual arguments whose lengths are less than the expected length
of their corresponding dummy argument are errors; but this needs
to be refined. Short actual arguments that are variables remain
errors, but those that are expressions can be (again) extended on
the right with blanks.

Differential Revision: https://reviews.llvm.org/D125115

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[flang] Fix ICE for passing a label for non alternate return arguments

When we pass an alternate return specifier to a regular (not an asterisk)
dummy argument, flang would throw an internal compile

[flang] Fix ICE for passing a label for non alternate return arguments

When we pass an alternate return specifier to a regular (not an asterisk)
dummy argument, flang would throw an internal compiler error of
derefencing a null pointer.
To avoid the ICE, a check was added.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D123947

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[flang] Add one semantic check for implicit interface

As Fortran 2018 C1533, a nonintrinsic elemental procedure shall not be
used as an actual argument. The semantic check for implicit iterface is
m

[flang] Add one semantic check for implicit interface

As Fortran 2018 C1533, a nonintrinsic elemental procedure shall not be
used as an actual argument. The semantic check for implicit iterface is
missed.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D124379

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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] Upgrade short actual character arguments to errors

f18 was emitting a warning about short character actual arguments to
subprograms and statement functions; every other compiler considers th

[flang] Upgrade short actual character arguments to errors

f18 was emitting a warning about short character actual arguments to
subprograms and statement functions; every other compiler considers this
case to be an error.

Differential Revision: https://reviews.llvm.org/D123731

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[flang] Improve appearance of message attachments

Error messages can have a list of attachments; these are used to point
to related source locations, supply additional information, and to
encapsulat

[flang] Improve appearance of message attachments

Error messages can have a list of attachments; these are used to point
to related source locations, supply additional information, and to
encapsulate error messages that were *not* emitted in a given context
to explain why a warning was justified.

This patch adds a message severity ("Because") for that last case,
and extends to AttachTo() API to provide a means for overriding
the severity of an attached message.

Some existing message attachments had their severities adjusted,
now that we're printing them. And operator==() for Message was
cleaned up while debugging after I noticed that it was recursively
O(N**2) and subject to returning a false positive.

Differential Revision: https://reviews.llvm.org/D123710

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[flang] Add one semantic check for allocatable/pointer argument association

The actual argument shall have deferred the same type parameters as
the dummy argument if the argument is allocatable or p

[flang] Add one semantic check for allocatable/pointer argument association

The actual argument shall have deferred the same type parameters as
the dummy argument if the argument is allocatable or pointer variable.
Currently programs not following this get one crash during execution.

Reviewed By: Jean Perier

Differential Revision: https://reviews.llvm.org/D122779

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[flang] add evaluate::IsAllocatableDesignator helper

Previously, some semantic checks that are checking if an entity is an
allocatable were relying on the expression being a designator whose
last sy

[flang] add evaluate::IsAllocatableDesignator helper

Previously, some semantic checks that are checking if an entity is an
allocatable were relying on the expression being a designator whose
last symbol has the allocatable attribute.

This is wrong since this was considering substrings and array sections of
allocatables as being allocatable. This is wrong (see NOTE 2 in
Fortran 2018 section 9.5.3.1).

Add evaluate::IsAllocatableDesignator to correctly test this.
Also add some semantic tests for ALLOCATED to test the newly added helper.
Note that ifort and nag are rejecting coindexed-named-object in
ALLOCATED (`allocated(coarray_scalar_alloc[2])`).
I think it is wrong given allocated argument is intent(in) as per
16.2.1 point 3.
So 15.5.2.6 point 4 regarding allocatable dummy is not violated (If the actual
argument is a coindexed object, the dummy argument shall have the INTENT (IN)
attribute.) and I think this is valid. gfortran accepts it.

The need for this helper was exposed in https://reviews.llvm.org/D122779.

Differential Revision: https://reviews.llvm.org/D122899

Co-authored-by: Peixin-Qiao <[email protected]>

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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] 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] Do not return true for pointer sub-object in IsPointerObject

evaluate::IsPointerObject used to return true for pointer suboject like
`pointer(10)` while these object are not pointers. This p

[flang] Do not return true for pointer sub-object in IsPointerObject

evaluate::IsPointerObject used to return true for pointer suboject like
`pointer(10)` while these object are not pointers. This prevented some
checks like 15.5.2.7 to be correctly enforced (e.g., it was possible to
pass `pointer(10)` to a non intent(in) dummy pointer).

After updating IsPointerObject behavior and adding a test for 15.5.2.7 in
call07.f90, a test in call03.f90 for 15.5.2.4(14) was failing.
It appeared the related semantics check was relying on IsPointerObject
to return true for `pointer(10)`. Adapt the code to detect pointer element
in another way.
While looking at the code, I also noticed that semantics was
rejecting `character(1)` pointer/assumed shape suboject when these are
allowed (the standard has a special case for character(1) in
15.5.2.4(14), and I verified that other compilers that enforce 15.5.2.4(14)
do accept this).

Differential Revision: https://reviews.llvm.org/D121377

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[flang] Distinguish usage and portability warning messages

Using recently established message severity codes, upgrade
non-fatal messages to usage and portability warnings as
appropriate.

Differenti

[flang] Distinguish usage and portability warning messages

Using recently established message severity codes, upgrade
non-fatal messages to usage and portability warnings as
appropriate.

Differential Revision: https://reviews.llvm.org/D121246

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[flang] Remove bogus messages for actual/dummy procedure argument compatibility

Add new IsCompatibleWith() member functions to many classes in evaluate::characteristics
that apply more nuanced compa

[flang] Remove bogus messages for actual/dummy procedure argument compatibility

Add new IsCompatibleWith() member functions to many classes in evaluate::characteristics
that apply more nuanced compatibility checking for function results, dummy
arguments, and procedure interfaces than the previous tests for complete
equivalence. Use IsCompatibleWith() in semantics for call checking.

Differential Revision: https://reviews.llvm.org/D120844

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[flang] Check constraint C711 correctly

An assumed-type actual argument that corresponds to an assumed-rank dummy
argument shall be assumed-shape or assumed-rank.

Differential Revision: https://rev

[flang] Check constraint C711 correctly

An assumed-type actual argument that corresponds to an assumed-rank dummy
argument shall be assumed-shape or assumed-rank.

Differential Revision: https://reviews.llvm.org/D120750

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[flang] Make source location more accurate for actual arguments

Track source location information when available for actual arguments
to procedure references, and use this information when checking

[flang] Make source location more accurate for actual arguments

Track source location information when available for actual arguments
to procedure references, and use this information when checking constraints
on calls so that error messages refer to specific actual arguments
rather than to the entire call.

Differential Revision: https://reviews.llvm.org/D119849

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[flang] Accept BOZ literals for some actual arguments

Consistent with previously documented policy, in which
BOZ literals are accepted in non-standard-conforming circumstances
where they can be conv

[flang] Accept BOZ literals for some actual arguments

Consistent with previously documented policy, in which
BOZ literals are accepted in non-standard-conforming circumstances
where they can be converted to an unambiguous known numeric type,
allow BOZ literals to be passed as an actual argument in a reference
to a procedure whose explicit interface has a corresponding dummy
argument with a numeric type to which the BOZ literal may be
converted. Improve error messages associated with BOZ literal
actual arguments, too: don't emit multiple errors.

Differential Revision: https://reviews.llvm.org/D117698

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[flang] Adjust names in Semantics that imply too much (NFC)

Some kinds of Fortran arrays are declared with the same syntax,
and it is impossible to tell from a shape (:, :) or (*) whether
the object

[flang] Adjust names in Semantics that imply too much (NFC)

Some kinds of Fortran arrays are declared with the same syntax,
and it is impossible to tell from a shape (:, :) or (*) whether
the object is assumed shape, deferred shape, assumed size, implied
shape, or whatever without recourse to more information about the
symbol in question. This patch softens the names of some predicate
functions (IsAssumedShape to CanBeAssumedShape) and makes others
more reflective of the syntax they represent (isAssumed to isStar)
in an attempt to encourage coders to seek and find definitive
predicate functions whose names deliver what they seem to mean.

Address TODO comments in IsSimplyContiguous() by using the
updated IsAssumedShape() predicate.

Differential Revision: https://reviews.llvm.org/D114829

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[flang] Fix generic resolution case

Don't try to convert INTEGER argument expressions to the kind of
the dummy argument when performing generic resolution; specific
procedures may be distinguished o

[flang] Fix generic resolution case

Don't try to convert INTEGER argument expressions to the kind of
the dummy argument when performing generic resolution; specific
procedures may be distinguished only by their kinds.

Differential Revision: https://reviews.llvm.org/D112240

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