[flang] Correct IsHostAssociated() to be true for BLOCK constructs

The predicate IsHostAssocited() was implemented in a way that would
return true only for cases of host association into a module or

[flang] Correct IsHostAssociated() to be true for BLOCK constructs

The predicate IsHostAssocited() was implemented in a way that would
return true only for cases of host association into a module or inner
subprogram. Technically, the use of a name in a BLOCK construct
that is not declared therein is considered in the Fortran standard
to also be a form of host association, and this matters when doing
error checking on DATA statements.

Differential Revision: https://reviews.llvm.org/D130388

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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] ERROR STOP is not an image control statement

The predicate that determines image control statements needs
to distinguish STOP (which is) from ERROR STOP (which isn't).

Differential Revision

[flang] ERROR STOP is not an image control statement

The predicate that determines image control statements needs
to distinguish STOP (which is) from ERROR STOP (which isn't).

Differential Revision: https://reviews.llvm.org/D127796

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[flang] Make generic resolution conform to 15.5.5.2 w/r/t host association

When two or more generic interfaces are available by declaration or
by USE association at different scoping levels, we need

[flang] Make generic resolution conform to 15.5.5.2 w/r/t host association

When two or more generic interfaces are available by declaration or
by USE association at different scoping levels, we need to search
the outer generic interfaces as well as the inner ones, but only after
the inner ones have failed to produce a specific procedure that matches
a given set of actual arguments. This means that it is possible for
a specific procedure of a generic interface of an inner scope to override
a conflicting specific procedure of a generic interface of an outer
scope.

Also cope with forward references to derived types when a generic
interface is also in scope.

Fixes LLVM bug https://github.com/llvm/llvm-project/issues/55240 and
LLVM bug https://github.com/llvm/llvm-project/issues/55300.

Differential Revision: https://reviews.llvm.org/D126587

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[flang] Accept defined assignment with CLASS(*) RHS

A utility predicate in semantics was incorrectly determining that
an INTERFACE ASSIGNMENT(=) (or other form of generic) could not have
a specific

[flang] Accept defined assignment with CLASS(*) RHS

A utility predicate in semantics was incorrectly determining that
an INTERFACE ASSIGNMENT(=) (or other form of generic) could not have
a specific procedure with an unlimited polymorphic second argument.
This led to a crash later in expression analysis. Fix, and
extend tests.

Differential Revision: https://reviews.llvm.org/D126151

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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] Accept POINTER followed by INTERFACE

As is already supported for dummy procedures, we need to also accept
declarations of procedure pointers that consist of a POINTER attribute
statement fol

[flang] Accept POINTER followed by INTERFACE

As is already supported for dummy procedures, we need to also accept
declarations of procedure pointers that consist of a POINTER attribute
statement followed by an INTERFACE block. (The case of an INTERFACE
block followed by a POINTER statement already works.)

While cleaning this case up, adjust the utility predicate IsProcedurePointer()
to recognize it (namely a SubprogramDetails symbol with Attr::POINTER)
and delete IsProcName(). Extend tests, and add better comments to
symbol.h to document the two ways in which procedure pointers are
represented.

Differential Revision: https://reviews.llvm.org/D125139

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[flang] Reverse a reversed type compatibility check

The semantic test for an intrinsic assignment to a polymorphic
derived type entity from a type that is an extension of its base
type was reversed,

[flang] Reverse a reversed type compatibility check

The semantic test for an intrinsic assignment to a polymorphic
derived type entity from a type that is an extension of its base
type was reversed, so it would allow assignments that it shouldn't
and disallowed some that it should; and the test case for it
incorectly assumed that the invalid semantics were correct.
Fix the code and the test, and add a new test for the invalid
case (LHS type is an extension of the RHS type).

Differential Revision: https://reviews.llvm.org/D125135

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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] Finer control over error recovery with GetExpr()

Prior to this patch, the semantics utility GetExpr() will crash
unconditionally if it encounters a typed expression in the parse
tree that ha

[flang] Finer control over error recovery with GetExpr()

Prior to this patch, the semantics utility GetExpr() will crash
unconditionally if it encounters a typed expression in the parse
tree that has not been set by expression semantics. This is the
right behavior when called from lowering, by which time it is known
that the program had no fatal user errors, since it signifies a
fatal internal error. However, prior to lowering, in the statement
semantics checking code, a more nuanced test should be used before
crashing -- specifically, we should not crash in the face of a
missing typed expression when in error recovery mode.

Getting this right requires GetExpr() and its helper class to have
access to the semantics context, so that it can check AnyFatalErrors()
before crashing. So this patch touches nearly all of its call sites.

Differential Revision: https://reviews.llvm.org/D123873

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[flang] Allow modification of construct entities

Construct entities from ASSOCIATE, SELECT TYPE, and SELECT RANK
are modifiable if the are associated with modifiable variables
without vector subscri

[flang] Allow modification of construct entities

Construct entities from ASSOCIATE, SELECT TYPE, and SELECT RANK
are modifiable if the are associated with modifiable variables
without vector subscripts. Update WhyNotModifiable() to accept
construct entities that are appropriate.

A need for more general error reporting from one overload of
WhyNotModifiable() caused its result type to change to
std::optional<parser::Message> instead of ::MessageFixedText,
and this change had some consequences that rippled through
call sites.

Some test results that didn't allow for modifiable construct
entities needed to be updated.

Differential Revision: https://reviews.llvm.org/D123722

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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] Fix bogus error from assignment to CLASS(*)

Assignment semantics was coughing up bad errors and crashes for
intrinsic assignments to unlimited polymorphic entities while
looking for any (imp

[flang] Fix bogus error from assignment to CLASS(*)

Assignment semantics was coughing up bad errors and crashes for
intrinsic assignments to unlimited polymorphic entities while
looking for any (impossible) user defined ASSIGNMENT(=) generic
or intrinsic type conversion.

Differential Revision: https://reviews.llvm.org/D122440

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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] Catch I/O of bad derived type at compile time

Derived types with allocatable and pointer components cannot
be used in I/O data transfer statements unless they have defined
I/O procedures ava

[flang] Catch I/O of bad derived type at compile time

Derived types with allocatable and pointer components cannot
be used in I/O data transfer statements unless they have defined
I/O procedures available (as type-bound or regular generics).
These cases are caught as errors by the I/O runtime library,
but it would be better if they were flagged during compilation.

(Address comment in review: don't use explicit name string lengths.)

Differential Revision: https://reviews.llvm.org/D120675

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[flang] Allow DATA initialization of derived types w/ allocatable components

While one cannot of course statically initialize an allocatable component
of an instance of a derived type, its mere pres

[flang] Allow DATA initialization of derived types w/ allocatable components

While one cannot of course statically initialize an allocatable component
of an instance of a derived type, its mere presence should not prevent
DATA initialization of the other nonallocatable components. Semantics
was treating the existence of an allocatable component as a case of
"default initialization", which it is, but not one that should run
afoul of C877. Add another Boolean argument to IsInitialized() to allow
for a more nuanced test.

Differential Revision: https://reviews.llvm.org/D119449

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[flang] Distinguish intrinsic from non-intrinsic modules

For "USE, INTRINSIC", search only for intrinsic modules;
for "USE, NON_INTRINSIC", do not recognize intrinsic modules.
Allow modules of both

[flang] Distinguish intrinsic from non-intrinsic modules

For "USE, INTRINSIC", search only for intrinsic modules;
for "USE, NON_INTRINSIC", do not recognize intrinsic modules.
Allow modules of both kinds with the same name to be used in
the same source file (but not in the same scoping unit, a
constraint of the standard that is now enforced).

The symbol table's scope tree now has a single instance of
a scope with a new kind, IntrinsicModules, whose children are
the USE'd intrinsic modules (explicit or not). This separate
"top-level" scope is a child of the single global scope and
it allows both intrinsic and non-intrinsic modules of the same
name to exist in the symbol table. Intrinsic modules' scopes'
symbols now have the INTRINSIC attribute set.

The search path directories need to make a distinction between
regular directories and the one(s) that point(s) to intrinsic
modules. I allow for multiple intrinsic module directories in
the second search path, although only one is needed today.

Differential Revision: https://reviews.llvm.org/D118631

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[flang] Intrinsic assignment of distinct but "same" derived types

Subclause 7.5.2.4 lists conditions under which two distinct derived
types are to be considered the same type for purposes of argumen

[flang] Intrinsic assignment of distinct but "same" derived types

Subclause 7.5.2.4 lists conditions under which two distinct derived
types are to be considered the same type for purposes of argument
association, assignment, and so on. These conditions are implemented
in evaluate::IsTkCompatibleWith(), but assignment semantics doesn't
use it for testing for intrinsic assignment compatibility. Fix that.

Differential Revision: https://reviews.llvm.org/D117621

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[flang] Better messages for function vs. array errors

When a scalar-valued function with no distinct RESULT
is being called recursively in its own executable part,
emit a better message about the er

[flang] Better messages for function vs. array errors

When a scalar-valued function with no distinct RESULT
is being called recursively in its own executable part,
emit a better message about the error. Clean up the
code that resolves function vs. array ambiguities in
expression semantics.

Update to address review comment

Differential Revision: https://reviews.llvm.org/D117577

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[flang] Rearrange prototype & code placement of IsCoarray()

A quick fix last week to the shared library build caused
the predicate IsCoarray(const Symbol &) to be moved from
Semantics to Evaluate.

[flang] Rearrange prototype & code placement of IsCoarray()

A quick fix last week to the shared library build caused
the predicate IsCoarray(const Symbol &) to be moved from
Semantics to Evaluate. This patch completes that move in
a way that properly combines the existing IsCoarray() tests
for expressions and other object with the test for a symbol.

Differential Revision: https://reviews.llvm.org/D114806

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[flang] Move IsCoarray() to fix shared library build

The predicate IsCoarray() needs to be in libFortranEvaluate so that
IsSaved() can call it without breaking the shared library build.

Pushed with

[flang] Move IsCoarray() to fix shared library build

The predicate IsCoarray() needs to be in libFortranEvaluate so that
IsSaved() can call it without breaking the shared library build.

Pushed without pre-commit review as I'm moving code around and
the fix to the shared build is confirmed.

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[flang] Add -fno-automatic, refine IsSaved()

This legacy option (available in other Fortran compilers with various
spellings) implies the SAVE attribute for local variables on subprograms
that are n

[flang] Add -fno-automatic, refine IsSaved()

This legacy option (available in other Fortran compilers with various
spellings) implies the SAVE attribute for local variables on subprograms
that are not explicitly RECURSIVE. The SAVE attribute essentially implies
static rather than stack storage. This was the default setting in Fortran
until surprisingly recently, so explicit SAVE statements & attributes
could be and often were omitted from older codes. Note that initialized
objects already have an implied SAVE attribute, and objects in COMMON
effectively do too, as data overlays are extinct; and since objects that are
expected to survive from one invocation of a procedure to the next in static
storage should probably be explicit initialized in the first place, so the
use cases for this option are somewhat rare, and all of them could be
handled with explicit SAVE statements or attributes.

This implicit SAVE attribute must not apply to automatic (in the Fortran sense)
local objects, whose sizes cannot be known at compilation time. To get the
semantics of IsSaved() right, the IsAutomatic() predicate was moved into
Evaluate/tools.cpp to allow for dynamic linking of the compiler. The
redundant predicate IsAutomatic() was noticed, removed, and its uses replaced.

GNU Fortran's spelling of the option (-fno-automatic) was added to
the clang-based driver and used for basic sanity testing.

Differential Revision: https://reviews.llvm.org/D114209

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[flang] Make builtin types more easily accessible; use them

Rearrange the contents of __builtin_* module files a little and
make sure that semantics implicitly USEs the module __Fortran_builtins
bef

[flang] Make builtin types more easily accessible; use them

Rearrange the contents of __builtin_* module files a little and
make sure that semantics implicitly USEs the module __Fortran_builtins
before processing each source file. This ensures that the special derived
types for TEAM_TYPE, EVENT_TYPE, LOCK_TYPE, &c. exist in the symbol table
where they will be available for use in coarray intrinsic function
processing.

Update IsTeamType() to exploit access to the __Fortran_builtins
module rather than applying ad hoc name tests. Move it and some
other utilities from Semantics/tools.* to Evaluate/tools.* to make
them available to intrinsics processing.

Add/correct the intrinsic table definitions for GET_TEAM, TEAM_NUMBER,
and THIS_IMAGE to exercise the built-in TEAM_TYPE as an argument and
as a result.

Add/correct/extend tests accordingly.

Differential Revision: https://reviews.llvm.org/D110356

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[flang] Include default component initialization in static initializers

The combined initializers constructed from DATA statements and explicit
static initialization in declarations needs to include

[flang] Include default component initialization in static initializers

The combined initializers constructed from DATA statements and explicit
static initialization in declarations needs to include derived type
component default initializations, overriding those default values
without complaint with values from explicit DATA statement or declaration
initializations when they overlap. This also has to work for objects
with storage association due to EQUIVALENCE. When storage association causes
default component initializations to overlap, emit errors if and only
if the values differ (See Fortran 2018 subclause 19.5.3, esp. paragraph
10).

The f18 front-end has a module that analyzes and converts DATA statements
into equivalent static initializers for objects. For storage-associated
objects, compiler-generated objects are created that overlay the entire
association and fill it with a combined initializer. This "data-to-inits"
module already exists, and this patch is essentially extension and
clean-up of its machinery to complete the job.

Also: emit EQUIVALENCE to module files; mark compiler-created symbols
and *don't* emit those to module files; check non-static EQUIVALENCE
sets for conflicting default component initializations, so lowering
doesn't have to check them or emit diagnostics.

Differential Revision: https://reviews.llvm.org/D109022

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