[flang] Add IsElementalProcedure() predicate

Replace most tests of the explicit Attr::ELEMENTAL symbol flag with
a new predicate IsElementalProcedure() that works correctly for alternate
ENTRY point

[flang] Add IsElementalProcedure() predicate

Replace most tests of the explicit Attr::ELEMENTAL symbol flag with
a new predicate IsElementalProcedure() that works correctly for alternate
ENTRY points and does the right thing for procedure interfaces that
reference elemental intrinsic functions like SIN() whose elemental
nature does not propagate.

Differential Revision: https://reviews.llvm.org/D129022

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[flang] Support check for BIND statement entity

As Fortran 2018 8.6.4(1), the BIND statement specifies the BIND attribute
for a list of variables and common blocks.

Reviewed By: klausler

Different

[flang] Support check for BIND statement entity

As Fortran 2018 8.6.4(1), the BIND statement specifies the BIND attribute
for a list of variables and common blocks.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D127120

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[flang] Enforce C1552, no binding labels allowed for internal procedures

If BIND(C) appears on an internal procedure, it must have a null binding
label, i.e. BIND(C,NAME="").

Also address conflicts

[flang] Enforce C1552, no binding labels allowed for internal procedures

If BIND(C) appears on an internal procedure, it must have a null binding
label, i.e. BIND(C,NAME="").

Also address conflicts with D127725 which was merged during development.

Differential Revision: https://reviews.llvm.org/D128676

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[flang] Add semantic check for C1520

As Fortran 2018 C1520, if proc-language-binding-spec with NAME= is
specified, then proc-decl-list shall contain exactly one proc-decl,
which shall neither have t

[flang] Add semantic check for C1520

As Fortran 2018 C1520, if proc-language-binding-spec with NAME= is
specified, then proc-decl-list shall contain exactly one proc-decl,
which shall neither have the POINTER attribute nor be a dummy procedure.
Add this check.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D127725

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[flang] Fix one regression failure related to BIND(C) statement

For BIND(C) statement, two common block with the same name can have the
same bind name. Fix the regression failure by adding this chec

[flang] Fix one regression failure related to BIND(C) statement

For BIND(C) statement, two common block with the same name can have the
same bind name. Fix the regression failure by adding this check. Also add
the regression tests.

Co-authored-by: Jean Perier <[email protected]>

Reviewed By: clementval

Differential Revision: https://reviews.llvm.org/D127841

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[flang] Complement one-to-one association check of bind name and entity name

As Fortran 2018 C802 and C873, if bind name is specified, there can only
be only one entity. The check for common block i

[flang] Complement one-to-one association check of bind name and entity name

As Fortran 2018 C802 and C873, if bind name is specified, there can only
be only one entity. The check for common block is missed before. As
Fortran 2018 8.5.5 point 2, the bind name is one identifier, which is
unique. That is, one entity can not have multiple bind names. Also add
this check.

Reviewed By: klausler, Jean Perier

Differential Revision: https://reviews.llvm.org/D126961

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[flang] Add one semantic check for procedure bind(C) interface-name

As Fortran 2018 C1521, in procedure declaration statement, if
proc-language-binding-spec (bind(c)) is specified, the proc-interfac

[flang] Add one semantic check for procedure bind(C) interface-name

As Fortran 2018 C1521, in procedure declaration statement, if
proc-language-binding-spec (bind(c)) is specified, the proc-interface
shall appear, it shall be an interface-name, and interface-name shall
be declared with a proc-language-binding-spec.

Reviewed By: klausler, Jean Perier

Differential Revision: https://reviews.llvm.org/D127121

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[flang] Add check for conflict of BIND(C) and Parameter attributes

The entity with BIND(C) attribute cannot be a named constant, so the
BIND(C) and parameter attributes are conflicted. Add check for

[flang] Add check for conflict of BIND(C) and Parameter attributes

The entity with BIND(C) attribute cannot be a named constant, so the
BIND(C) and parameter attributes are conflicted. Add check for it.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D126654

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[flang] Add semantic check for named constant as function result

Similar to procedure argument, the function result cannot be one
named constant.

Reviewed By: klausler

Differential Revision: https

[flang] Add semantic check for named constant as function result

Similar to procedure argument, the function result cannot be one
named constant.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D126693

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[flang] Support BIND(C) variable scope check

As Fortran 2018 C819, a variable with the BIND attribute shall be declared
in the specification part of a module. Add the support for this check.

Review

[flang] Support BIND(C) variable scope check

As Fortran 2018 C819, a variable with the BIND attribute shall be declared
in the specification part of a module. Add the support for this check.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D126653

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[flang] Fix false error for multiple defined I/O subroutines

User-defined derived type I/O subroutines need to be unique for
a given type and operation in any scope, but it is acceptable
to have mor

[flang] Fix false error for multiple defined I/O subroutines

User-defined derived type I/O subroutines need to be unique for
a given type and operation in any scope, but it is acceptable
to have more than one defined I/O subroutine so long as only one
of them is visible.

Differential Revision: https://reviews.llvm.org/D126152

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[flang] Allow more forward references to ENTRY names

Forward references to ENTRY names to pass them as actual procedure arguments
don't work in all cases, exposing some basic ordering problems in
na

[flang] Allow more forward references to ENTRY names

Forward references to ENTRY names to pass them as actual procedure arguments
don't work in all cases, exposing some basic ordering problems in
name resolution for these symbols. Refactor; create all the
necessary procedure symbols, and either function result or host association
symbols (for subroutines), at the time that the subprogrma scope is
created, so that the names exist in the scope as text "before"
the ENTRY is processed in name resolution. Some processing
remains in PostEntryStmt() so that we can check that an ENTRY with
an explicit distinct RESULT doesn't also have declarations for the
ENTRY name.

Differential Revision: https://reviews.llvm.org/D126142

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[flang] Ignore BIND(C) binding name conflicts of inner procedures

The binding names of inner procedures with BIND(C) are not exposed
to the loader and should be ignored for potential conflict errors

[flang] Ignore BIND(C) binding name conflicts of inner procedures

The binding names of inner procedures with BIND(C) are not exposed
to the loader and should be ignored for potential conflict errors.

Differential Revision: https://reviews.llvm.org/D126141

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[flang] Warn for the limit on name length

As fortran 2018 C601, the maximum length of a name is 63 characters.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D125371

[flang] Enforce limit on rank + corank

Fortran 2018 requires that a compiler allow objects whose rank + corank
is 15, and that's our maximum; detect and diagnose violations.

Differential Revision:

[flang] Enforce limit on rank + corank

Fortran 2018 requires that a compiler allow objects whose rank + corank
is 15, and that's our maximum; detect and diagnose violations.

Differential Revision: https://reviews.llvm.org/D125153

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[flang] Enforce a program not including more than one main program

As Fortran 2018 5.2.2 states, a program shall consist of exactly one
main program. Add this semantic check.

Reviewed By: klausler

[flang] Enforce a program not including more than one main program

As Fortran 2018 5.2.2 states, a program shall consist of exactly one
main program. Add this semantic check.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D125186

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[flang] Do not ICE on recursive function definition in function result

The following code causes the compiler to ICE in several places due to
lack of support of recursive procedure definitions throu

[flang] Do not ICE on recursive function definition in function result

The following code causes the compiler to ICE in several places due to
lack of support of recursive procedure definitions through the function
result.

function foo() result(r)
procedure(foo), pointer :: r
end function foo

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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] Correct interaction between generics and intrinsics

Fortran allows a generic interface to have he same name as an
intrinsic procedure. If the intrinsic is explicitly marked with
the INTRINS

[flang] Correct interaction between generics and intrinsics

Fortran allows a generic interface to have he same name as an
intrinsic procedure. If the intrinsic is explicitly marked with
the INTRINSIC attribute, restrictions apply (C848) - the generic
must contain only functions or subroutines, depending on the
intrinsic. Explicit or not, the generic overrides the intrinsic,
but the intrinsic behavior must still be available for calls
whose actual arguments do not match any of the specific procedures.

Semantics was not checking constraint C848, and it didn't allow
an explicit INTRINSIC attribute on a name of a generic interface.

Differential Revision: https://reviews.llvm.org/D123713

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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] 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] Accommodate module subprograms defined in the same module

The symbol table, name resolution, and semantic checks for module
subprograms -- esp. for MODULE FUNCTION and MODULE SUBROUTINE, but

[flang] Accommodate module subprograms defined in the same module

The symbol table, name resolution, and semantic checks for module
subprograms -- esp. for MODULE FUNCTION and MODULE SUBROUTINE, but
also MODULE PROCEDURE -- essentially assumed that the subprogram
would be defined in a submodule of the (sub)module containing its
interface. However, it is conforming to instead declare a module
subprogram in the *same* (sub)module as its interface, and we need
to handle that case.

Since this case involves two symbols in the same scope with the same
name, the symbol table details for subprograms have been extended
with a pointer to the original module interface, rather than relying
on searching in scopes.

Differential Revision: https://reviews.llvm.org/D120839

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[flang] Avoid bogus error for specification expression

When a scope's symbol has characteriztics whose specification
expressions depend on other non-constant symbols in the same scope,
f18 rightfull

[flang] Avoid bogus error for specification expression

When a scope's symbol has characteriztics whose specification
expressions depend on other non-constant symbols in the same scope,
f18 rightfully emits an error. However, in the case of usage in
specification expressions involving host association, the program is not
invalid. This can arise, for example, in the case of an internal
function whose result's attributes use host-associated variables.

Differential Revision: https://reviews.llvm.org/D119565

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[flang] Improve error message (initialized variable in pure subprogram)

When variable with the SAVE attribute appears in a pure subprogram,
emit a more specialized error message if the SAVE attribut

[flang] Improve error message (initialized variable in pure subprogram)

When variable with the SAVE attribute appears in a pure subprogram,
emit a more specialized error message if the SAVE attribute was acquired
from static initialization.

Differential Revision: https://reviews.llvm.org/D117699

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