[flang] Merge pull request flang-compiler/f18#60 from ThePortlandGroup/tsk2

Implement parse tree rewriting.

Original-commit: flang-compiler/f18@ac0c8ca08ec9cbf35ac2f51b9ee04bb2dce1f9b0
Reviewed-on: https://github.com/flang-compiler/f18/pull/60

[flang] Move ConvertToAssignment into class StmtFunctionStmt.

Original-commit: flang-compiler/f18@e3eaca38fd0c30765474c2a46ae4d6c36796af07
Reviewed-on: https://github.com/flang-compiler/f18/pull/60

[flang] Merge parse-tree-mutator.h into parse-tree-visitor.h

Use the latter for visiting and mutating and delete the former.

Original-commit: flang-compiler/f18@ac5a098ca7187eeb5d5bd2104c8d29363075b368
Reviewed-on: https://github.com/flang-compiler/f18/pull/60
Tree-same-pre-rewrite: false

[flang] Address review comments.

Original-commit: flang-compiler/f18@d3a363d6cbcb154201f45670c0a60edbff260719
Reviewed-on: https://github.com/flang-compiler/f18/pull/60
Tree-same-pre-rewrite: false

[flang] Implement parse tree rewriting.

Add parse-tree-mutator.h like parse-tree-visitor.h except that the Walk
functions take non-const references to parse tree nodes so the Pre and
Post methods of the mutator that are passed around can make changes to
the parse tree.

Change ExecutionPart to be a class that wraps a list so that it can be
identified during parse tree walking.

Add Symbol* field to parser::Name for the result of symbol resolution.
In parse tree dumper, dump symbol when it is there instead of just name.

Add RewriteParseTree to walk the parse tree, fill in resolved symbols in
Name nodes, and make necessary changes to the structure. Currently that
consists of rewriting statement functions as array assignments when
appropriate.

In ResolveNames, call RewriteParseTree if the resolution was successful.
Recognize a statement function that comes after a mis-identified
statement function and report an error. resolve08.f90 tests this case.

Add -fdebug-dump-symbols to dump the scope tree and symbols in each scope.
This is implemented by DumpSymbols in resolve-names.cc. Add an optional
symbol to scopes that correspond to symbols (e.g. subprograms). Remove
debug output from ResolveNamesVisitor as this option can be used instead.

Original-commit: flang-compiler/f18@9cd337226521c7f3d2b149983ed677def55baa29
Reviewed-on: https://github.com/flang-compiler/f18/pull/60
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#59 from ThePortlandGroup/pmk-messages

Messaging work

Original-commit: flang-compiler/f18@f6b879ab1070b940df3c97b0a1251ed0f73f8475
Reviewed-on: https://github.com/flang-compiler/f18/pull/59

[flang] Defer message accumulation until it is known that messages will be produced.

Original-commit: flang-compiler/f18@8485d44efd6a0b78b091b613d7c4d8eb95231533
Reviewed-on: https://github.com/flang-compiler/f18/pull/59

[flang] Suppress messages in lookAhead and negated parsers.

Original-commit: flang-compiler/f18@6c00f10364e97a9e131869120814f499faec8bd0
Reviewed-on: https://github.com/flang-compiler/f18/pull/59
Tree-same-pre-rewrite: false

[flang] reformat

Original-commit: flang-compiler/f18@4a4648facdf671b75cc2f63b13f7f382e4206039
Reviewed-on: https://github.com/flang-compiler/f18/pull/59
Tree-same-pre-rewrite: false

[flang] Remove questionable swap() routines in ParseState and Messages.

Original-commit: flang-compiler/f18@9a8155ebca1b3f0a7d345a7a832dcc765623f096
Reviewed-on: https://github.com/flang-compiler/f18/pull/59
Tree-same-pre-rewrite: false

[flang] Avoid a std::move() when emplacing new messages.

Original-commit: flang-compiler/f18@39c0e1fdba24283db4f45a23d643b3db36ac6b42
Reviewed-on: https://github.com/flang-compiler/f18/pull/59
Tree-same-pre-rewrite: false

[flang] Remove obsolete #if 0 code.

Original-commit: flang-compiler/f18@0195cd5646359ef8932fe3ef9f03ad9ed6866260
Reviewed-on: https://github.com/flang-compiler/f18/pull/59
Tree-same-pre-rewrite: false

[flang] Avoid std::shared_ptr<> in favor of reference counting.

Original-commit: flang-compiler/f18@116c9881c9d0c523c19a3201027b5c4974f6416e
Reviewed-on: https://github.com/flang-compiler/f18/pull/59
Tree-same-pre-rewrite: false

[flang] Message experiment: defer all message generation until non-speculative.

Original-commit: flang-compiler/f18@b6ce95ca3a6e21a7bfd89afbb522d8a78ebce6c2
Reviewed-on: https://github.com/flang-compiler/f18/pull/59
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#58 from ThePortlandGroup/tsk1

Add statement functions to symbol table

Original-commit: flang-compiler/f18@c69f975aeeb3b1617b8aa8509f72828b5fa4f955
Reviewed-on: https://github.com/flang-compiler/f18/pull/58

[flang] Address review comments.

Original-commit: flang-compiler/f18@f9a54f71712c7b8124591b5fcc27d2e2af9313a5
Reviewed-on: https://github.com/flang-compiler/f18/pull/58

[flang] Add statement functions to symbol table

SubprogramDetails: Store dummy args and result as symbols, not names.

Symbol: Save list of occurrences (i.e. SourceNames that map to the same
symbol). This is needed to map Names in the parse tree back to symbols,
and will probably be useful when reporting errors.
Improve dumping of symbols.

resolve-names.cc: Recognize statement functions. They are treated like
function subprograms but the result type and type of dummy arguments come
from the enclosing scope. The implicit rules from the enclosing scope need
to be copied in.

Original-commit: flang-compiler/f18@44e4fb4b6cc107fad299e80046673804c15a2ac2
Reviewed-on: https://github.com/flang-compiler/f18/pull/58
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#57 from ThePortlandGroup/pmk-bugfix

fix misrecogition of actual argument "a==b"

Original-commit: flang-compiler/f18@56ee8bf349fcd0749febd2e5ecff738394539f41
Reviewed-on: https://github.com/flang-compiler/f18/pull/57

[flang] fix misrecogition of actual argument "a==b" as keyword "a=" and value "=b"

Original-commit: flang-compiler/f18@52b18374194742b62d906ca4ee07ef09755c672e
Reviewed-on: https://github.com/flang-compiler/f18/pull/57

[flang] Merge pull request flang-compiler/f18#56 from ThePortlandGroup/pmk-proc-component

Simplify grammar for "variable" as used in proc-component-ref and pointer ass't

Original-commit: flang-compiler/f18@3bbfe5656f030441611fec355fa48731f3709ad7
Reviewed-on: https://github.com/flang-compiler/f18/pull/56

[flang] Resolve array specifications of entities.

Add ArraySpecVisitor to recognize the various forms of array specifications.
They are tracked in arraySpec_ and attrArraySpec_. Both are needed because
a declaration like `integer, dimension(4) :: x(2,2), y` has two different
array-specs.

The method DeclareEntity was extracted out to handle the common part for
EntityDecl, ObjectDecl, and DimensionStmt. AllocatableStmt and TargetStmt
are now handled through their contained ObjectDecl.

The test resolve07 checks the interactions between these kinds of declarations.

Rename ComponentArraySpec to ArraySpec as it doesn't just occur in components.

Fix some 'begin' and 'end' methods to start with upper-case letters.

Original-commit: flang-compiler/f18@113bfc4fe7781b11c3d3399254a6fcea1afeedd5
Reviewed-on: https://github.com/flang-compiler/f18/pull/56

[flang] run clang-format

Original-commit: flang-compiler/f18@8639d566dac60e6d756320fea44c0842999a6512
Reviewed-on: https://github.com/flang-compiler/f18/pull/56
Tree-same-pre-rewrite: false

[flang] add accessor to derived type definition

Original-commit: flang-compiler/f18@f73c70395e98c634087bc48a4d64765a863b531a
Reviewed-on: https://github.com/flang-compiler/f18/pull/56
Tree-same-pre-rewrite: false

[flang] Add missing accessors in 'type' classes

Original-commit: flang-compiler/f18@7b79fcfbc57121b8204e0afb411d393f8b986730
Reviewed-on: https://github.com/flang-compiler/f18/pull/56
Tree-same-pre-rewrite: false

[flang] fix misrecognition of a bounds-spec-list or bound-remapping-list in a pointer-assignment-stmt

Original-commit: flang-compiler/f18@32148441f5e8a500648c61709c50c8530d2395db
Reviewed-on: https://github.com/flang-compiler/f18/pull/56

[flang] Use DataRef as a better name for the data-ref production.  Use DataRef instead of Variable for LHS of pointer assignment.

Original-commit: flang-compiler/f18@ed5aeb8e3c9a1af839765c45c491a0fb0af802d1
Reviewed-on: https://github.com/flang-compiler/f18/pull/56
Tree-same-pre-rewrite: false

[flang] Simplify proc-component-ref and variable parsing, do not try to support function calls via components of function results.

Original-commit: flang-compiler/f18@05886ddb80e31f3caec96cbaba1fea274db7c61a
Reviewed-on: https://github.com/flang-compiler/f18/pull/56
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#55 from ThePortlandGroup/tsk8

Add -fdebug-dump-parse-tree and -fdebug-resolve-names

Original-commit: flang-compiler/f18@a62dceb218e709c8cd71415ade757c73a81e8ce8
Reviewed-on: https://github.com/flang-compiler/f18/pull/55

[flang] Add -fdebug-dump-parse-tree and -fdebug-resolve-names

"f18 -fdebug-resolve-names -fparse-only ..." is equivalent to what
test-type used to do, so the test-type executable can be eliminated.

-fdebug-dump-parse-tree does the parse-tree dumping that test-sema
does, but test-sema does more so I have left it alone.

Original-commit: flang-compiler/f18@8b3816528e6463acd18bbf6ed29c40869b15ea3a
Reviewed-on: https://github.com/flang-compiler/f18/pull/55

[flang] Merge pull request flang-compiler/f18#54 from ThePortlandGroup/tsk6

Fix integration problem between PR flang-compiler/f18#51 and PR flang-compiler/f18#53.

Original-commit: flang-compiler/f18@1ec186ab77bde164d003dee9c92a820145fd957d
Reviewed-on: https://github.com/flang-compiler/f18/pull/54

[flang] Fix integration problem between PR flang-compiler/f18#51 and PR flang-compiler/f18#53.

Stephane added an access that returned ComponentArraySpec and meanwhile
I renamed it to ArraySpec.

Original-commit: flang-compiler/f18@b8e47bc7a52861ea388ee3a19e44221656e62166
Reviewed-on: https://github.com/flang-compiler/f18/pull/54

[flang] Merge pull request flang-compiler/f18#53 from ThePortlandGroup/tsk6

Resolve array specifications of entities.

Original-commit: flang-compiler/f18@9abf24ab2fb38e82992eecf3fc3d53c3a4334672
Reviewed-on: https://github.com/flang-compiler/f18/pull/53

[flang] Resolve array specifications of entities.

Add ArraySpecVisitor to recognize the various forms of array specifications.
They are tracked in arraySpec_ and attrArraySpec_. Both are needed because
a declaration like `integer, dimension(4) :: x(2,2), y` has two different
array-specs.

The method DeclareEntity was extracted out to handle the common part for
EntityDecl, ObjectDecl, and DimensionStmt. AllocatableStmt and TargetStmt
are now handled through their contained ObjectDecl.

The test resolve07 checks the interactions between these kinds of declarations.

Rename ComponentArraySpec to ArraySpec as it doesn't just occur in components.

Fix some 'begin' and 'end' methods to start with upper-case letters.

Original-commit: flang-compiler/f18@3d4d7430b559a135a3eddf8291449106195406a0
Reviewed-on: https://github.com/flang-compiler/f18/pull/53

[flang] Merge pull request flang-compiler/f18#52 from ThePortlandGroup/tsk8

Improve include file sorting.

Original-commit: flang-compiler/f18@c36717a5e006b102d78a9ceabc1870e2852c7933
Reviewed-on: https://github.com/flang-compiler/f18/pull/52

[flang] Improve include file sorting.

Includes like "../dir/file.h" should sort after local includes.
This change fixes that and applies the new formatting.

Now the order (in reverse) is:
- system includes
- includes from llvm or clang (this is from the default IncludeCategories)
- includes of ../something
- everything else

Original-commit: flang-compiler/f18@324643d63a1842ddfea9ea2a70ebb363f9ced8cc
Reviewed-on: https://github.com/flang-compiler/f18/pull/52

[flang] Merge pull request flang-compiler/f18#51 from ThePortlandGroup/sch_types

add missing accessors to types

Original-commit: flang-compiler/f18@9b54154c63b8e6424c2727c51716de289e75ff39
Reviewed-on: https://github.com/flang-compiler/f18/pull/51

[flang] run clang-format

Original-commit: flang-compiler/f18@f40a1dd9c849cb49ac6c3d656dfd8141a88cf068
Reviewed-on: https://github.com/flang-compiler/f18/pull/51

[flang] add accessor to derived type definition

Original-commit: flang-compiler/f18@d971f4f1acd9e1e2cfb76c390a671238f39e6951
Reviewed-on: https://github.com/flang-compiler/f18/pull/51
Tree-same-pre-rewrite: false

[flang] Add missing accessors in 'type' classes

Original-commit: flang-compiler/f18@42a46f35e82661e0f0a2c62d12448072dabcd5f7
Reviewed-on: https://github.com/flang-compiler/f18/pull/51
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#49 from ThePortlandGroup/tsk6

Continue work on name resolution.

Original-commit: flang-compiler/f18@7e271af1e5f8397441963802b1dff10e66fcf9ac
Reviewed-on: https://github.com/flang-compiler/f18/pull/49

[flang] Use ENUM_CLASS macro for Scope::Kind.

Original-commit: flang-compiler/f18@3492e8d247c33e1053170df0c7bb552608c5234f
Reviewed-on: https://github.com/flang-compiler/f18/pull/49

[flang] Continue work on name resolution.

In Symbol and Scope, use SourceName (== parser::CharBlock) in place of
Name (== std::string) so that names in the symtab have provenance. We
may ultimately have multiple source locations associated with a symbol.

ImplicitRules: Add isImplicitNoneType and isImplicitNoneExternal flags.

MessageHandler: Add methods to emit messages associated with source
locations.

Detect conflicting declarations of symbols (e.g. as subprogram and
variable).

Handle attribute statements like ASYNCHRONOUS statement: make sure the
symbol is present and set the attribute on it. Check that these all have
a type declared by the end of the specification part if IMPLICIT NONE.

Find variables named in Variable and Expr nodes and check they have
types declared if IMPLICIT NONE. Otherwise, make sure they are in the
symtab and apply the implicit type rules at the end of the scope.

Push a scope for MainProgram nodes and add a symbol for the name if it
has one.

Rename Scope::map_type to Scope::mapType

Add tests for errors currently being detected. There is no framework for
running them yet, just source files with the expected errors in
comments.

Original-commit: flang-compiler/f18@39e6fa4169644b2c2b94ee611949fbc0766599a2
Reviewed-on: https://github.com/flang-compiler/f18/pull/49
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#48 from ThePortlandGroup/pmk-nag-h

Parse NAG tests (no execution)

Original-commit: flang-compiler/f18@b18347b098b050ef95e8fc6ea5b894f575a2a933
Reviewed-on: https://github.com/flang-compiler/f18/pull/48

[flang] Document support for CONVERT= extension.

Original-commit: flang-compiler/f18@a4674f074354fbfb169d6402b0afec411c769b2a
Reviewed-on: https://github.com/flang-compiler/f18/pull/48

[flang] Add length check so that memcmp() on source does not go past the end of input and make valgrind complain.

Original-commit: flang-compiler/f18@475e9db03548bd45ae81201561579de3119d6587
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Fix unparsing of renamed operators in USE statements.

Original-commit: flang-compiler/f18@4152b604e31c8f685d3d19493d9459e9f7258863
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Always put parens on unparsed ENTRY statement in case there is a suffix.

Original-commit: flang-compiler/f18@d0d1a5789b1fc49dfcac44f5082e600ee85da453
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Fix unparsing of pointer-decls with deferred shape.

Original-commit: flang-compiler/f18@3c7c7eced5898e92692dcce1584b014f046c5283
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Repair negative scale factors in formats.

Original-commit: flang-compiler/f18@0e90d2db3a05a7c3f4f52aa02de87ecfaf55d48d
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Tweak recent disambiguations after more testing.

Original-commit: flang-compiler/f18@82fb9838b98da2215513477f83657058aca515d1
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Remove a needless std::move() call, and be more careful about line continuation.

Original-commit: flang-compiler/f18@e26421513fd8d55680bf3b5a261c7aee036d9318
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Remove some needless std::move() calls for readability.

Original-commit: flang-compiler/f18@88aadf45dccb6c7fe0443345842d6ecced2258bd
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Better solution in grammar for a data statement value parse.

Original-commit: flang-compiler/f18@05b437506af704b59d120bb516c5a1658f504987
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Handle pp-directives amid continuations correctly, and fix a Hollerith ambiguity.

Original-commit: flang-compiler/f18@dcd7820a97c7ca7617b0a2848e2310d4c2b2c848
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Adjust TODO messages to reflect deliberate behavior.

Original-commit: flang-compiler/f18@9636998ee44439e46e10bcfe0bbb6e6e74b14c6f
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Fix naming: list_type -> listType

Original-commit: flang-compiler/f18@9bf6adc41cc5d5209647722a04a8f6c3e935fdb1
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Rearrange alternatives in data statement values to put longer parse earlier.

Original-commit: flang-compiler/f18@867cefaafbc135bde1033b9e28d055250c44baca
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Prevent misrecognition of a digit string that is the kind parameter of a character literal from being misrecognized as an integer literal.

Original-commit: flang-compiler/f18@bd7ed0b162b7cc4e89e0d08e22e8676d59261931
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Parse unlimited format item -- needed to adjust its precedence in grammar.

Original-commit: flang-compiler/f18@318bebe485a3104c78cad7b74d693678fcc65030
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Parser mistakenly attempted error recovery in specification part when it saw END statement with label.

Original-commit: flang-compiler/f18@69b8ad8380a36502a41abf247478c232979f38f6
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Fix two errors in the grammar (array constructors with type but no values did not consume the ::, and ERR= was omitted from CLOSE().  Add CONVERT= extension to OPEN().

Original-commit: flang-compiler/f18@e3e584f06083166ae9e69375de2831bcd9dd4923
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Crash more gracefully when files include themselves.

Original-commit: flang-compiler/f18@6da9ec422824b7e86b10bb368fedd5b734063ce8
Reviewed-on: https://github.com/flang-compiler/f18/pull/48
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#43 from ThePortlandGroup/pmk2

Avoid most uses of Boolean-valued Pre() callbacks in unparse.cc.

Original-commit: flang-compiler/f18@1b8ff5f07de4a7c7d70454aeaf708407d1be8edc
Reviewed-on: https://github.com/flang-compiler/f18/pull/43

[flang] Avoid most uses of Boolean-valued Pre() callbacks in unparse.cc.

Original-commit: flang-compiler/f18@f4ea2f94f3fa3b228eb18ae68eac8b22d02c7a83
Reviewed-on: https://github.com/flang-compiler/f18/pull/43

[flang] Merge pull request flang-compiler/f18#46 from ThePortlandGroup/tsk8

Change API of Scope to match std::map

Original-commit: flang-compiler/f18@e34e2ac0c8feba4e95f141bc84b3007cf57c185e
Reviewed-on: https://github.com/flang-compiler/f18/pull/46

[flang] Address review comments.

Make map_type private -- it is not part of the API.

Add cbegin() and cend().

Original-commit: flang-compiler/f18@1ad699dbfdcab2c3960b1dda438572d23dcffbb4
Reviewed-on: https://github.com/flang-compiler/f18/pull/46

[flang] Change API of Scope to match std::map

The Scope can be thought of as (among other things) a mapping of Name to
Symbol. This change reflects that by changing the API to match std::map.

Original-commit: flang-compiler/f18@37f6ad73ccf37439c7b0c57d7c2bbf12b65ed751
Reviewed-on: https://github.com/flang-compiler/f18/pull/46
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#45 from ThePortlandGroup/sjs-doc

Add snippet about trigraphs

Original-commit: flang-compiler/f18@c4a397e501efa5d880ccf41f603926149302c1dc
Reviewed-on: https://github.com/flang-compiler/f18/pull/45

[flang] Add snippet about trigraphs

Original-commit: flang-compiler/f18@551f2ccd06861f317bfb6fe092c2274af3fc96c1
Reviewed-on: https://github.com/flang-compiler/f18/pull/45

[flang] Merge pull request flang-compiler/f18#41 from ThePortlandGroup/tsk6

 Collect implicit type rules and report related errors.

Original-commit: flang-compiler/f18@ff4f1432811bffce66d88f69da0308bfbff98f20
Reviewed-on: https://github.com/flang-compiler/f18/pull/41

[flang] Address review comments.

Maintain stack of ImplicitRules in parallel with the scope stack.
I doesn't have to live as long as the scopes.

Allow for '_', '$', and '@' in ImplicitRules if they come through from
the parser.

Original-commit: flang-compiler/f18@b70e9fc9564a2cae40fce71ee7c035a502bdb7f3
Reviewed-on: https://github.com/flang-compiler/f18/pull/41

[flang] Address code review comments.

Original-commit: flang-compiler/f18@b0dd8959057e14531ffc0e6dbc63c3cef4932997
Reviewed-on: https://github.com/flang-compiler/f18/pull/41
Tree-same-pre-rewrite: false

[flang] Collect implicit type rules and report related errors.

ImplicitRules maintains a mapping of initial character of an identifier
to its implicit type.

ImplicitRulesVisitor visits the ImplicitStmt and related parse tree
nodes and updates the rules.

Emit errors messages in these cases:
- implicit type specified more than once for a letter
- IMPLICIT statement and IMPLICIT NONE in same scope
- IMPLICIT statement and IMPLICIT NONE(TYPE) in same scope
- more than one IMPLICIT NONE in a scope
- IMPLICIT statement with empty range of letters
- IMPLICIT NONE statement after PARAMETER statement
- TYPE or EXTERNAL repeated in an IMPLICIT NONE statement

Also start emitting error messages through the parser::Messages
interface. An instance of Messages is created from the cooked source and
saved in the MessageHandler class. It tracks the source location of the
current statement and provides a way to emit messages associated with
that statement.

Original-commit: flang-compiler/f18@e12fea98502883dbcafb7627d45deb2a6aa6098d
Reviewed-on: https://github.com/flang-compiler/f18/pull/41
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#42 from ThePortlandGroup/pmk1

Generalize Attrs for arbitrary enums, implement with std::bitset<>.

Original-commit: flang-compiler/f18@28a9fc0b9e4a387678eb05395ed6d888e1b88912
Reviewed-on: https://github.com/flang-compiler/f18/pull/42

[flang] Address review comments.

Original-commit: flang-compiler/f18@66ecc10722135e5f9f3f8d68ac6795a4ba5e0727
Reviewed-on: https://github.com/flang-compiler/f18/pull/42

[flang] Generalize semantics/attr.h into enum-set.h, implementing it atop std::bitset.

Original-commit: flang-compiler/f18@d827c8bcc318dd8e740ca00e2176d428c1baadf7
Reviewed-on: https://github.com/flang-compiler/f18/pull/42
Tree-same-pre-rewrite: false

[flang] Improvements to memory-mapped source files.

Original-commit: flang-compiler/f18@67066468e5de31fc8e6e392236d545662d2bb801
Reviewed-on: https://github.com/flang-compiler/f18/pull/42
Tree-same-pre-rewrite: false

[flang] Avoid having too many file descriptors open or using mmap() for small files.

Original-commit: flang-compiler/f18@750483a1bef7fb4bef59e6b13e2bc34e98ec379a
Reviewed-on: https://github.com/flang-compiler/f18/pull/42
Tree-same-pre-rewrite: false

[flang] Correct order of steps in idealized preprocessor description.

Original-commit: flang-compiler/f18@3107999501a1d81861c3f578ca78787244a9f026
Reviewed-on: https://github.com/flang-compiler/f18/pull/42
Tree-same-pre-rewrite: false

[flang] Do not allow "-" to denote standard input on INCLUDE/#include.

Original-commit: flang-compiler/f18@f645036a16c19d5ba946bc7405197a2205dff751
Reviewed-on: https://github.com/flang-compiler/f18/pull/42
Tree-same-pre-rewrite: false

[flang] Fix __VA_ARGS__, was broken due to typo.

Original-commit: flang-compiler/f18@ba90b1fc27fc18ba045a033ec27e458cd6b2e958
Reviewed-on: https://github.com/flang-compiler/f18/pull/42
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#39 from ThePortlandGroup/pmk-recovery2

Error recovery in specification parts

Original-commit: flang-compiler/f18@074ce568ff43038568418b299b1027471620e338
Reviewed-on: https://github.com/flang-compiler/f18/pull/39

[flang] Resolve some TODOs in the grammar.

Original-commit: flang-compiler/f18@6ef9e2388bfc7f9b7ac5966196d9e1918220d797
Reviewed-on: https://github.com/flang-compiler/f18/pull/39

[flang] Error recovery for specification part.

Original-commit: flang-compiler/f18@187075c7a052c3d38760890c63127b4016be383a
Reviewed-on: https://github.com/flang-compiler/f18/pull/39
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#38 from ThePortlandGroup/pmk-recovery

Messaging and error recovery work

Original-commit: flang-compiler/f18@073210bf91ddc91e7f2e773861d9a40a2fd34de4
Reviewed-on: https://github.com/flang-compiler/f18/pull/38

[flang] Address review comments (thanks!).

Original-commit: flang-compiler/f18@1e61fbaeae5402fcd0c732de244bfe02aadfe6ff
Reviewed-on: https://github.com/flang-compiler/f18/pull/38

[flang] Add documentation.

Original-commit: flang-compiler/f18@4114c9e695ff740199ec015a041be3ac0fa8b779
Reviewed-on: https://github.com/flang-compiler/f18/pull/38
Tree-same-pre-rewrite: false

[flang] More clean-up in token-parsers.h.

Original-commit: flang-compiler/f18@320213454237dcda9011f2ee48c258c118d83f0c
Reviewed-on: https://github.com/flang-compiler/f18/pull/38
Tree-same-pre-rewrite: false

[flang] Debugging and a TODO.

Original-commit: flang-compiler/f18@4fab40bc37e870e3b4fa039d51d7cc8b672f2f36
Reviewed-on: https://github.com/flang-compiler/f18/pull/38
Tree-same-pre-rewrite: false

[flang] Better error recovery, some debugging.

Original-commit: flang-compiler/f18@b7509f0e5be796e0b29a481215f3950c8276d76d
Reviewed-on: https://github.com/flang-compiler/f18/pull/38
Tree-same-pre-rewrite: false

[flang] Revamp messaging.  Add ""_err_en_US to denote fatal error messages.

Original-commit: flang-compiler/f18@7ddc807a1bb6b33613ebdfab9c089bb2eabdcea9
Reviewed-on: https://github.com/flang-compiler/f18/pull/38
Tree-same-pre-rewrite: false

[flang] Fix debug-parser.h after recent merge.

Original-commit: flang-compiler/f18@97b6df606c4add591c212ff4b8aa5f4b8e3de765
Reviewed-on: https://github.com/flang-compiler/f18/pull/38
Tree-same-pre-rewrite: false

[flang] Fix indentation bug in unparsed output that I introduced in last merge.

Original-commit: flang-compiler/f18@aa0ba5acacc02a360504661e457446a370dff4c2
Reviewed-on: https://github.com/flang-compiler/f18/pull/38
Tree-same-pre-rewrite: false

[flang] Work around clang-format issue by using "auto" where type is obvious.

Original-commit: flang-compiler/f18@7499bccaa938547d3af29c7b859f1fede2e718be
Reviewed-on: https://github.com/flang-compiler/f18/pull/38
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#36 from ThePortlandGroup/tsk6

Continue work on name resolution

Original-commit: flang-compiler/f18@acaee7b44f4d9fd87800032eb385685407343eb8
Reviewed-on: https://github.com/flang-compiler/f18/pull/36

[flang] Fix bug parsing "implicit none(type)"

"implicit none(type)" was being recognized as "implicit none(external)".

Original-commit: flang-compiler/f18@0cc88678369afa49b8e435eb5e9d43fc119b37d0
Reviewed-on: https://github.com/flang-compiler/f18/pull/36

[flang] Respond to review comments.

Original-commit: flang-compiler/f18@d2497a6485e1dc8ea5fc7ba1dfb01d7603f57bfa
Reviewed-on: https://github.com/flang-compiler/f18/pull/36
Tree-same-pre-rewrite: false

[flang] Continue work on name resolution

Enhance DeclTypeSpecVisitor to find derived-type-specs, including with
type parameter values.

Change DerivedTypeSpec so it only needs the name of the derived type,
not the definition, as that isn't necessarily known when we encounter
it.

Fix how memory is managed in DeclTypeSpec: Intrinsic type specs aren't a
problem -- they are one of a few types that live throughout the program.
Derived type specs are dynamically allocated and the memory is owned by
the DeclTypeSpec -- it allocates it when a DeclTypeSpec for a derived
type is created and deletes it when it is destroyed. Pass around
references to TypeSpecs rather than pointers as they can never be null.

In AttrsVisitor, DeclTypeSpecVisitor, ResolveNamesVisitor: make most
functions out-of-line to clean up the class declaration.

In AttrsVisitor, use preprocessor to simplify the simple case of
encountering a parse-tree class causing an attribute to be set.
Handle all such attributes.

Remove old testing code from type.cc.

Remove some of the declarations for IntExpr and IntConst -- they are
only placeholder classes anyway. Don't distinguish kind and length
parameter values.

Original-commit: flang-compiler/f18@e172b5121274a3cfc597f062da1ea32aa56039d9
Reviewed-on: https://github.com/flang-compiler/f18/pull/36
Tree-same-pre-rewrite: false

[flang] Merge pull request flang-compiler/f18#37 from ThePortlandGroup/pmk-minor

Roll up some small changes to resolve TODOs

Original-commit: flang-compiler/f18@e3d5b7256c787848d58f3696111963912a115f20
Reviewed-on: https://github.com/flang-compiler/f18/pull/37

[flang] Elide a useless local variable that used to be a formal argument.

Original-commit: flang-compiler/f18@419b5d07eeccda8bf2320b2adce0bb5adb55b0fd
Reviewed-on: https://github.com/flang-compiler/f18/pull/37