[flang] Fix parser crash (#105875)

The production for a bare file unit number in an I/O statement checks
that the scalar integer expression isn't followed by "=", in order to
disambiguate FLUSHN f

[flang] Fix parser crash (#105875)

The production for a bare file unit number in an I/O statement checks
that the scalar integer expression isn't followed by "=", in order to
disambiguate FLUSHN from FLUSHN=1, and to not treat a control specifier
keyword as an integer expression. The implementation of this check used
!"="_tok, which has the side effect of producing no error message; this
can lead to a parsing crash later when a failed parse of an erroneous
program is found to have produced no errors. Rewrite as a lookAhead call
for those characters that acually can follow a bare unit number.

Fixes https://github.com/llvm/llvm-project/issues/105779.

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[flang] Emit just one warning for a bad format edit descriptor

An attempt to use an edit descriptor (other than A or L) in a FORMAT
statement without arequired 'w' width will elicit warnings from bo

[flang] Emit just one warning for a bad format edit descriptor

An attempt to use an edit descriptor (other than A or L) in a FORMAT
statement without arequired 'w' width will elicit warnings from both
the parser and the I/O checker in semantics. Remove the warning from
the parser.

Differential Revision: https://reviews.llvm.org/D155977

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[flang] CUDA Fortran - part 1/5: parsing

Begin upstreaming of CUDA Fortran support in LLVM Flang.

This first patch implements parsing for CUDA Fortran syntax,
including:
- a new LanguageFeature en

[flang] CUDA Fortran - part 1/5: parsing

Begin upstreaming of CUDA Fortran support in LLVM Flang.

This first patch implements parsing for CUDA Fortran syntax,
including:
- a new LanguageFeature enum value for CUDA Fortran
- driver change to enable that feature for *.cuf and *.CUF source files
- parse tree representation of CUDA Fortran syntax
- dumping and unparsing of the parse tree
- the actual parsers for CUDA Fortran syntax
- prescanning support for !@CUF and !$CUF
- basic sanity testing via unparsing and parse tree dumps

... along with any minimized changes elsewhere to make these
work, mostly no-op cases in common::visitors instances in
semantics and lowering to allow them to compile in the face
of new types in variant<> instances in the parse tree.

Because CUDA Fortran allows the kernel launch chevron syntax
("call foo<<<blocks, threads>>>()") only on CALL statements and
not on function references, the parse tree nodes for CallStmt,
FunctionReference, and their shared Call were rearranged a bit;
this caused a fair amount of one-line changes in many files.

More patches will follow that implement CUDA Fortran in the symbol
table and name resolution, and then semantic checking.

Differential Revision: https://reviews.llvm.org/D150159

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[flang] Improve error recovery for bad/missing construct END statements

When a multi-statement construct should end with a particular END statement
like "END SELECT", and that construct's END statem

[flang] Improve error recovery for bad/missing construct END statements

When a multi-statement construct should end with a particular END statement
like "END SELECT", and that construct's END statement is missing or
unrecognizable, the error recovery productions should not misinterpret
a program unit END statement that follows and consume it as a misspelled
construct END statement. Doing so leads to cascading errors or a failed parse.

Differential Revision: https://reviews.llvm.org/D136896

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[flang] Avoid spurious warnings in pedantic mode from FORMAT items

In free form source, pedantic mode will elicit portability warnings
about missing spaces when a token string ends with a character

[flang] Avoid spurious warnings in pedantic mode from FORMAT items

In free form source, pedantic mode will elicit portability warnings
about missing spaces when a token string ends with a character that
can be in an identifier and there is no space between that last token
character and a following character that can also be part of an identifier.

This behavior doesn't really work well for the token strings that are
parsed for edit descriptors in FORMAT statements. For example, the
'F' in FORMAT(F7.3) is followed by a digit, but obviously no space is
necessary. Free form or not, FORMATs are their own odd little world.

This patch adds trailing blanks to these FORMAT edit descriptor token
parsers to disable the missing space check, and extends the documentation
for token string parsing to explain why this technique works.

Differential Revision: https://reviews.llvm.org/D129023

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[flang] Add explanatory messages to grammar for language extensions

Extend "extension<LanguageFeature>()" to incorporate an explanatory
message better than the current generic "nonstandard usage:".

[flang] Add explanatory messages to grammar for language extensions

Extend "extension<LanguageFeature>()" to incorporate an explanatory
message better than the current generic "nonstandard usage:".

Differential Revision: https://reviews.llvm.org/D122035

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[flang] Fix parsing of WRITE(I+J) with more accurate look-ahead

The parsing of I/O units uses look-ahead to discriminate between
keywords, variables and expressions as part of distinguishing interna

[flang] Fix parsing of WRITE(I+J) with more accurate look-ahead

The parsing of I/O units uses look-ahead to discriminate between
keywords, variables and expressions as part of distinguishing internal
from external I/O. The look-ahead was inaccurate for variables that
appear as the initial parts of expressions.

Differential Revision: https://reviews.llvm.org/D95743

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[flang] Recognize END FILE as ENDFILE in free form source

The ENDFILE statement may be spelled as two words.

Differential revision: https://reviews.llvm.org/D91377

[flang] Detect and rewrite ambiguous READ(CVAR)[,item-list]

READ(CVAR)[,item-list] with a character variable CVAR
could be parsed as an unformatted READ from an internal
unit or as a formatted READ

[flang] Detect and rewrite ambiguous READ(CVAR)[,item-list]

READ(CVAR)[,item-list] with a character variable CVAR
could be parsed as an unformatted READ from an internal
unit or as a formatted READ from the default external unit
with a needlessly parenthesized variable format. We parse
it as the former, but Fortran doesn't have unformatted
internal I/O.

Differential revision: https://reviews.llvm.org/D90493

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[flang] Implement nonstandard OPEN statement CARRIAGECONTROL specifier

Differential Revision: https://reviews.llvm.org/D87052

[flang] Process names in ASSIGN and assigned GOTO

Allow ASSIGNed integer variables as formats

Address review comment

Original-commit: flang-compiler/f18@361a151508b4a1940fc0669dead180be67964d8d
Re

[flang] Process names in ASSIGN and assigned GOTO

Allow ASSIGNed integer variables as formats

Address review comment

Original-commit: flang-compiler/f18@361a151508b4a1940fc0669dead180be67964d8d
Reviewed-on: https://github.com/flang-compiler/f18/pull/1099

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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] [LLVMify F18] Compiler module folders should have capitalised names (flang-compiler/f18#980)

This patch renames the modules in f18 to use a capital letter in the
module name

Signed-off-b

[flang] [LLVMify F18] Compiler module folders should have capitalised names (flang-compiler/f18#980)

This patch renames the modules in f18 to use a capital letter in the
module name

Signed-off-by: Caroline Concatto <caroline.concatto@arm.com>

Original-commit: flang-compiler/f18@d2eb7a1c443d1539ef12b6f027074a0eb15b1ea0
Reviewed-on: https://github.com/flang-compiler/f18/pull/980

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