[flang] Downgrade a fatal error to a warning

A non-CHARACTER expression in a CASE statement is allowed to have
a distinct kind (not type) from the expression in its SELECT CASE.
If a value in a CASE

[flang] Downgrade a fatal error to a warning

A non-CHARACTER expression in a CASE statement is allowed to have
a distinct kind (not type) from the expression in its SELECT CASE.
If a value in a CASE statement is out of range for the SELECT CASE
type, emit a warning, but it should not be a fatal error.

Differential Revision: https://reviews.llvm.org/D124544

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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] Error handling for out-of-range CASE values

Catch and nicely describe errors in CASE range values
that are out of range for the type of the SELECT CASE.

Differential Revision: https://revie

[flang] Error handling for out-of-range CASE values

Catch and nicely describe errors in CASE range values
that are out of range for the type of the SELECT CASE.

Differential Revision: https://reviews.llvm.org/D123708

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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

show more ...

[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] Fix integer CASE constant typing

Don't use just 128-bit integer as the type for integer
CASE statement constants. Use the actual type of the
literal constants that appeared.

Differential R

[flang] Fix integer CASE constant typing

Don't use just 128-bit integer as the type for integer
CASE statement constants. Use the actual type of the
literal constants that appeared.

Differential Review: https://reviews.llvm.org/D86875

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[flang] Reformat with latest clang-format and .clang-format

Original-commit: flang-compiler/f18@9fe84f45d7fd685051004678d6b5775dcc4c6f8f
Reviewed-on: https://github.com/flang-compiler/f18/pull/1094

[flang] Semantics for SELECT CASE

Prep for review

Respond to review comments

Fix first line in new test

Original-commit: flang-compiler/f18@12f6f30600db4cb3902677cd42764450ddeda5e0
Reviewed-on: h

[flang] Semantics for SELECT CASE

Prep for review

Respond to review comments

Fix first line in new test

Original-commit: flang-compiler/f18@12f6f30600db4cb3902677cd42764450ddeda5e0
Reviewed-on: https://github.com/flang-compiler/f18/pull/1089

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