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//===-- lib/Semantics/rewrite-parse-tree.cpp ------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "rewrite-parse-tree.h"
#include "flang/Common/indirection.h"
#include "flang/Parser/parse-tree-visitor.h"
#include "flang/Parser/parse-tree.h"
#include "flang/Parser/tools.h"
#include "flang/Semantics/scope.h"
#include "flang/Semantics/semantics.h"
#include "flang/Semantics/symbol.h"
#include "flang/Semantics/tools.h"
#include <list>
namespace Fortran::semantics {
using namespace parser::literals;
/// Convert misidentified statement functions to array element assignments
/// or pointer-valued function result assignments.
/// Convert misidentified format expressions to namelist group names.
/// Convert misidentified character variables in I/O units to integer
/// unit number expressions.
/// Convert misidentified named constants in data statement values to
/// initial data targets
class RewriteMutator {
public:
RewriteMutator(SemanticsContext &context)
: errorOnUnresolvedName_{!context.AnyFatalError()},
messages_{context.messages()} {}
// Default action for a parse tree node is to visit children.
template <typename T> bool Pre(T &) { return true; }
template <typename T> void Post(T &) {}
void Post(parser::Name &);
void Post(parser::SpecificationPart &);
bool Pre(parser::ExecutionPart &);
void Post(parser::ReadStmt &);
void Post(parser::WriteStmt &);
// Name resolution yet implemented:
// TODO: Can some/all of these now be enabled?
bool Pre(parser::EquivalenceStmt &) { return false; }
bool Pre(parser::Keyword &) { return false; }
bool Pre(parser::EntryStmt &) { return false; }
bool Pre(parser::CompilerDirective &) { return false; }
// Don't bother resolving names in end statements.
bool Pre(parser::EndBlockDataStmt &) { return false; }
bool Pre(parser::EndFunctionStmt &) { return false; }
bool Pre(parser::EndInterfaceStmt &) { return false; }
bool Pre(parser::EndModuleStmt &) { return false; }
bool Pre(parser::EndMpSubprogramStmt &) { return false; }
bool Pre(parser::EndProgramStmt &) { return false; }
bool Pre(parser::EndSubmoduleStmt &) { return false; }
bool Pre(parser::EndSubroutineStmt &) { return false; }
bool Pre(parser::EndTypeStmt &) { return false; }
private:
using stmtFuncType =
parser::Statement<common::Indirection<parser::StmtFunctionStmt>>;
bool errorOnUnresolvedName_{true};
parser::Messages &messages_;
std::list<stmtFuncType> stmtFuncsToConvert_;
};
// Check that name has been resolved to a symbol
void RewriteMutator::Post(parser::Name &name) {
if (!name.symbol && errorOnUnresolvedName_) {
messages_.Say(name.source, "Internal: no symbol found for '%s'"_err_en_US,
name.source);
}
}
static bool ReturnsDataPointer(const Symbol &symbol) {
if (const Symbol * funcRes{FindFunctionResult(symbol)}) {
return IsPointer(*funcRes) && !IsProcedure(*funcRes);
} else if (const auto *generic{symbol.detailsIf<GenericDetails>()}) {
for (auto ref : generic->specificProcs()) {
if (ReturnsDataPointer(*ref)) {
return true;
}
}
}
return false;
}
// Find mis-parsed statement functions and move to stmtFuncsToConvert_ list.
void RewriteMutator::Post(parser::SpecificationPart &x) {
auto &list{std::get<std::list<parser::DeclarationConstruct>>(x.t)};
for (auto it{list.begin()}; it != list.end();) {
bool isAssignment{false};
if (auto *stmt{std::get_if<stmtFuncType>(&it->u)}) {
if (const Symbol *
symbol{std::get<parser::Name>(stmt->statement.value().t).symbol}) {
const Symbol &ultimate{symbol->GetUltimate()};
isAssignment =
ultimate.has<ObjectEntityDetails>() || ReturnsDataPointer(ultimate);
if (isAssignment) {
stmtFuncsToConvert_.emplace_back(std::move(*stmt));
}
}
}
if (isAssignment) {
it = list.erase(it);
} else {
++it;
}
}
}
// Insert converted assignments at start of ExecutionPart.
bool RewriteMutator::Pre(parser::ExecutionPart &x) {
auto origFirst{x.v.begin()}; // insert each elem before origFirst
for (stmtFuncType &sf : stmtFuncsToConvert_) {
auto stmt{sf.statement.value().ConvertToAssignment()};
stmt.source = sf.source;
x.v.insert(origFirst,
parser::ExecutionPartConstruct{
parser::ExecutableConstruct{std::move(stmt)}});
}
stmtFuncsToConvert_.clear();
return true;
}
// When a namelist group name appears (without NML=) in a READ or WRITE
// statement in such a way that it can be misparsed as a format expression,
// rewrite the I/O statement's parse tree node as if the namelist group
// name had appeared with NML=.
template <typename READ_OR_WRITE>
void FixMisparsedUntaggedNamelistName(READ_OR_WRITE &x) {
if (x.iounit && x.format &&
std::holds_alternative<parser::Expr>(x.format->u)) {
if (const parser::Name * name{parser::Unwrap<parser::Name>(x.format)}) {
if (name->symbol && name->symbol->GetUltimate().has<NamelistDetails>()) {
x.controls.emplace_front(parser::IoControlSpec{std::move(*name)});
x.format.reset();
}
}
}
}
// READ(CVAR) [, ...] will be misparsed as UNIT=CVAR; correct
// it to READ CVAR [,...] with CVAR as a format rather than as
// an internal I/O unit for unformatted I/O, which Fortran does
// not support.
void RewriteMutator::Post(parser::ReadStmt &x) {
if (x.iounit && !x.format && x.controls.empty()) {
if (auto *var{std::get_if<parser::Variable>(&x.iounit->u)}) {
const parser::Name &last{parser::GetLastName(*var)};
DeclTypeSpec *type{last.symbol ? last.symbol->GetType() : nullptr};
if (type && type->category() == DeclTypeSpec::Character) {
x.format = common::visit(
[](auto &&indirection) {
return parser::Expr{std::move(indirection)};
},
std::move(var->u));
x.iounit.reset();
}
}
}
FixMisparsedUntaggedNamelistName(x);
}
void RewriteMutator::Post(parser::WriteStmt &x) {
FixMisparsedUntaggedNamelistName(x);
}
bool RewriteParseTree(SemanticsContext &context, parser::Program &program) {
RewriteMutator mutator{context};
parser::Walk(program, mutator);
return !context.AnyFatalError();
}
} // namespace Fortran::semantics
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