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
The CreateEntry() function in name resolution needs to allow for the name
of an alternate entry point already having been declared in the outer scope
as the homonymous specific procedure of a generic interface; e.g.,
interface foo
module procedure foo
end interface
subroutine bar
entry foo
end subroutine
Differential Revision: https://reviews.llvm.org/D126436
A recent change fixed the processing of BIND(C,NAME=expr) character
expressions so that they are evaluated as constants in the scope of
the subprogram. However, when the character name expression results
in an empty value after trimming, the compiler emits a warning message,
and this message is now causing a crash due to a lack of statement
context. To fix, extend the deferred processing of the BIND(C,NAME="")
so that a basic statement context exists.
Differential Revision: https://reviews.llvm.org/D126416
The scalar-default-character-expression that defines the interoperable
name of a function or subroutine (or interface) must have its names
resolved within the context of the subprogram, despite its appearance
on a function-stmt or a subroutine-stmt. Failure to do so can lead
to bogus errors or to incorrect results.
The solution is to defer name resolution for function-stmt suffixes
(but not entry-stmt suffixes) and for subroutine-stmt language binding
specifications to EndSubprogram(). (Their resolution only need to be
deferred to the end of the specification part, but it's cleanest to
deal with it in EndSubprogram().)
Differential Revision: https://reviews.llvm.org/D126153
Name resolution for subprograms checks whether the name is already
present in the enclosing scope as a generic interface, so that the
case of a generic with the same name as one of its specifics can be
handled. The particular means by which the enclosing scope is searched
for the name would resolve the name (bind a symbol to it) as a side
effect. This turns out to be the wrong thing to do when the subprogram
is going to have its symbol created in another scope to cope with its
BIND(C,NAME="name") name, and its Fortran name is already present in the
enclosing scope for a subprogram of the same name but without
BIND(C,NAME="name").
A very long explanation for a one-line fix, sorry. In short, change
the code to look up the name but not resolve it at that point.
Differential Revision: https://reviews.llvm.org/D126149
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
Intrinsic module names are not in the user's namespace, so they
are free to declare global names that conflict with intrinsic
modules.
Differential Revision: https://reviews.llvm.org/D126140
In a function, ENTRY E without an explicit RESULT() creates a
function result entity also named E that is storage associated with
the enclosing function's result. f18 was emitting an incorrect error
message if that function result E was referenced without any
declaration prior to its ENTRY statement when it should have been
implicitly declared instead.
Differential Revision: https://reviews.llvm.org/D125144
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
DATA statements in inner procedures were not treating undeclared objects
as implicitly declared variables if the DATA statement appeared in a
specification part; they were treated as host-associated symbols instead.
This was incorrect. Fix DATA statement name resolution to always treat
DATA as if it had appeared in the executable part.
Differential Revision: https://reviews.llvm.org/D125129
When processing an entry-stmt in name resolution, attrs_ was
reset before SetBindNameOn was called, causing the symbol to lose
the binding label information.
Differential Revision: https://reviews.llvm.org/D125097
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
The code below causes flang to crash with an exception.
After fixing the crash flang with an internal error "no symbol found for 'bar'"
This change fixes all the issues.
program name
implicit none
integer, parameter :: bar = 1
integer foo(bar) /bar*2/
end program name
Reviewed By: kiranchandramohan, klausler
Differential Revision: https://reviews.llvm.org/D124914
Name resolution fails with a bogus "is not a variable" error message
when a host-associated object appears in a NAMELIST group. The root
cause is that ConvertToObjectEntity() returns false for host-associated
objects. Fix that, and also apply a similar fix to ConvertToProcEntity()
nearby.
Differential Revision: https://reviews.llvm.org/D124541
At the top level of program units in a source file, two subprograms
are allowed to have the same name if at least one of them has a
distinct interoperable binding name. F18's symbol table requires
(most) symbols in a scope to have distinct names, though. Solve
by using compiler-created names for the symbols of global scope
subprograms that have interoperable binding names.
Differential Revision: https://reviews.llvm.org/D124295
A recent change that corrected the name resolution of a generic interface
when the same name was visible in scope incorrectly prevented a local
generic from shadowing an outer name that is not a generic, subprogram,
or derived type -- e.g., a simple variable -- leading to an inappropriate
error message.
Differential Revision: https://reviews.llvm.org/D124276
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().
The x%KIND inquiry needs to be supported when 'x' is itself
a complex part reference or a type parameter inquiry.
Differential Revision: https://reviews.llvm.org/D123733
A POINTER attribute statement is allowed to add the POINTER attribute
to a procedure entity that has already been declared, e.g. with an
INTERFACE block.
Differential Revision: https://reviews.llvm.org/D123732
For parameterized derived type component initializers whose
expressions' types depend on parameter values, f18's current
scheme of analyzing the initialization expression once during
name resolution fails. For example,
type :: pdt(k)
integer, kind :: k
real :: component = real(0.0, kind=k)
end type
To handle such cases, it is necessary to re-analyze the parse
trees of these initialization expressions once for each distinct
initialization of the type.
This patch adds code to wipe an expression parse tree of its
typed expressions, and update those of its symbol table pointers
that reference type parameters, and then re-analyze that parse
tree to generate the properly typed component initializers.
Differential Revision: https://reviews.llvm.org/D123728
Items in NAMELIST groups might be host-associated implicitly-typed
variables, but name resolution can't know that when the NAMELIST
appears in a specification part and the host's execution part has
not yet been analyzed. So defer NAMELIST group item name resolution
to the end of the execution part. This is safe because nothing
else in name resolution depends on whether a variable is in a
NAMELIST group or not.
Differential Revision: https://reviews.llvm.org/D123723
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
It is possible for generic interfaces of equivalent (but not necessarily
identical -- operator(.eq.) is equivalent to operator(==)) names to
be declared in a host scope and a nested scope, and the nested declaration
should function as an extension of the host's.
Differential Revision: https://reviews.llvm.org/D123719
A generic interface (however spelled) can have the same name as
an intrinsic procedure in the same scope. When an explicit INTRINSIC
attribute statement appears in a nested scope, semantics was
unconditionally declaring a new symbol that hid the generic entirely.
Catch this case and create instead a host association symbol for
the generic that can then be decorated with the INTRINSIC attribute.
Differential Revision: https://reviews.llvm.org/D123718
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
When a type specification appears in the prefix of a FUNCTION statement,
defer its processing as late as possible so that any symbols in the
tpe specification can be resolved in the function's scope to local
declarations, including use-associated symbols. f18 was already doing
this deferral in a limited form for derived types, and this patch
makes it work for intrinsic type parameter values as well.
In short, "real(kind(x)) function foo(x)" now works as it should.
"As late as possible" means the end of the specification part, or
the first appearance of the function result name in the specification
part.
Differential Revision: https://reviews.llvm.org/D123705
Fortran admits a few ways to have multiple symbols with the
same name in the same scope. Two of them involve generic
interfaces (from INTERFACE or GENERIC, the syntax doesn't matter);
these are allowed to inhabit a scope with either a derived type or
a subprogram that is also a specific procedure of the generic.
(But not both a derived type and a subprogram; they could not
cohabit a scope anyway, generic or not.)
In cases of USE association, f18 needs to be capable of combining
use-associated generic interfaces with other use-associated entities.
Two generics get merged (this case was nearly correct); a generic
and a derived type can merge into a GenericDetails with a shadowed
derivedType(); and a generic can replace or ignore a use-associated
procedure of the same name so long as that procedure is already
one of its specifics.
Further, these modifications to the use-associated generic
interface must be made to a local copy of the symbol. The previous
code was messing directly with the symbol in the module's scope.
The fix is basically a reimplementation of the member function
DoAddUse() in name resolution.
Differential Revision: https://reviews.llvm.org/D123704
Error messages can have a list of attachments; these are used to point
to related source locations, supply additional information, and to
encapsulate error messages that were *not* emitted in a given context
to explain why a warning was justified.
This patch adds a message severity ("Because") for that last case,
and extends to AttachTo() API to provide a means for overriding
the severity of an attached message.
Some existing message attachments had their severities adjusted,
now that we're printing them. And operator==() for Message was
cleaned up while debugging after I noticed that it was recursively
O(N**2) and subject to returning a false positive.
Differential Revision: https://reviews.llvm.org/D123710
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
To make it easier to find things that are not yet implemented, I'm changing the
messages that appear in the compiler's output to all have the string "not yet
implemented:".
These changes apply to files in the front end. I have another set of changes
to files in the lowering code.
Differential Revision: https://reviews.llvm.org/D122355
Name resolution was crashing while processing the ENTRY statement
due to a lack of special-case code necessary to handle the indirection
needed when the generic has the same name as the ENTRY.
Differential Revision: https://reviews.llvm.org/D122050
Using recently established message severity codes, upgrade
non-fatal messages to usage and portability warnings as
appropriate.
Differential Revision: https://reviews.llvm.org/D121246
F18 presently has fatal and non-fatal diagnostic messages. We'd like
to make non-fatal warnings stand out better in the output of the compiler.
This will turn out to be a large change that affects many files.
This patch is just the first part. It converts a Boolean isFatal_ data
member of the message classes into a severity code, and defines four
of these codes (Error, Warning, Portability, and a catch-all Other).
Later patches will result from sweeping over the parser and semantics,
changing most non-fatal diagnostic messages into warnings and portability
notes.
Differential Revision: https://reviews.llvm.org/D121228
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
Name resolution was properly probing the table of unrestricted
specific intrinsics to find "abs", but failing to capture the
result type and save it in the created symbol table entry.
Differential Revision: https://reviews.llvm.org/D120749
It is generally an error when a USE-associated name clashes
with a name defined locally, but not in all cases; a generic
interface can be both USE-associated and locally defined.
This works, but not when there is also a local subprogram
with the same name, which is valid when that subprogram is
a specific of the local generic. A bogus error issues at
the point of the USE because name resolution will have already
defined a symbol for the local subprogram.
The solution is to collect the names of local generics when
creating the program tree, and then create their symbols as
well if their names are also local subprograms, prior to any
USE association processing.
Differential Revision: https://reviews.llvm.org/D119566
Fortran allows forward references to derived types, including
function results that are typed in a prefix of a FUNCTION statement.
If a type is defined in the body of the function, a reference to
that type from a prefix on the FUNCTION statement must resolve to
the local symbol, even and especially when that type shadows one
from the host scope.
The solution is to defer the processing of that type until the
end of the function's specification part. But the language doesn't
allow for forward references to other names in the prefix, so defer
the processing of the type only when it is not an intrinsic type.
The data structures in name resolution that track this information
for functions needed to become a stack in order to make this work,
since functions can contain interfaces that are functions.
Differential Revision: https://reviews.llvm.org/D119448
Previously, when calling a procedure implicitly for which a global scope
procedure symbol with the same name existed, semantics resolved the
procedure name in the call to the global symbol without checking that
the symbol interface was compatible with the implicit interface of the
call.
This could cause expression rewrite and lowering to later badly process
the implicit call assuming a different result type or an explicit
interface. This could lead to lowering crash in case the actual argument
were incompatible with the dummies from the explicit interface.
Emit errors in the following problematic cases:
- If the result type from the symbol did not match the one from the
implicit interface.
- If the symbol requires an explicit interface.
This patch still allows calling an F77 like procedure with different
actual argument types than the one it was defined with because it is
correctly supported in lowering and is a feature in some program
(it is a pointer cast). The two cases that won't be accepted have
little chance to make much sense. Results returning ABIs may differ
depending on the return types, and function that requires explicit
interface usually requires descriptors or specific processing that
is incompatible with implicit interfaces.
Note that this patch is not making a deep analysis, and it will only
catch mistakes if a global symbol and an implicit interface are
involved. Cases where the user provided a conflicting explicit
interface would still require a pass after name resolution to study
conflicts more deeply. But these cases will not crash lowering or
trigger expression rewrite to do weird things.
Differential Revision: https://reviews.llvm.org/D119274
When a scope uses an explicit IMPORT statement to import a
symbol from the scope's host, it should not emit a bogus error
message later if that symbol is used in a specification construct.
The code that checks for imports being hidden by local declarations
was not allowing for the presence of host association (or USE)
indirection symbols in the local scope. Fix by using GetUltimate()
before checking for the hidden symbol.
Differential Revision: https://reviews.llvm.org/D118747
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
ENTRY statement names in module subprograms were not acceptable for
use as a "module procedure" in a generic interface, but should be.
ENTRY statements need to have symbols with place-holding
SubprogramNameDetails created for them in order to be visible in
generic interfaces. Those symbols are created from the "program
tree" data structure. This patch adds ENTRY statement names to the
program tree data structure and uses them to generate SubprogramNameDetails
symbols.
Differential Revision: https://reviews.llvm.org/D117345
Derived types with SEQUENCE must have data components of sequence
types; but this rule is relaxed as common an extension in the case of
pointer components, whose targets' types are not really relevant
to the implementation requirements of sequence types.
Differential Revision: https://reviews.llvm.org/D117158
It's not conforming to specify the SAVE attribute more than
once for a variable, but it also doesn't hurt anything and
isn't fatal in other Fortran compilers. Downgrade the
message to a warning for better portability.
Differential Revision: https://reviews.llvm.org/D117153
Implements part of the legacy "DEC structures" feature from
VMS Fortran. STRUCTUREs are processed as if they were derived
types with SEQUENCE. DATA-like object entity initialization
is supported as well (e.g., INTEGER FOO/666/) since it was used
for default component initialization in structures. Anonymous
components (named %FILL) are also supported.
These features, and UNION/MAP, were already being parsed.
An omission in the collection of structure field names in the
case of nested structures with entity declarations was fixed
in the parser.
Structures are supported in modules, but this is mostly for
testing purposes. The names of fields in structures accessed
via USE association cannot appear with dot notation in client
code (at least not yet). DEC structures antedate Fortran 90,
so their actual use in applications should not involve modules.
This patch does not implement UNION/MAP, since that feature
would impose difficulties later in lowering them to MLIR types.
In the meantime, if they appear, semantics will issue a
"not yet implemented" error message.
Differential Revision: https://reviews.llvm.org/D117151
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
Fold the legacy intrinsic functions LGE, LGT, LLE, & LLT
by rewriting them into character relational expressions and
then folding those. Also fix folding of comparisons of
character values of distinct lengths: the shorter value must
be padded with blanks. (This fix exposed some bad test cases,
which are also fixed.)
Differential Revision: https://reviews.llvm.org/D111843
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
