[flang-commits] [flang] [flang] Fix error from semantics on use associated procedure pointer (PR #107928)
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Mon Sep 9 15:28:19 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-flang-semantics
Author: Peter Klausler (klausler)
<details>
<summary>Changes</summary>
Use associated procedure pointers were eliciting bogus errors from semantics if their modules also contained generic procedure interfaces of the same name. (The compiler handles this case correctly when the specific procedure of the same name is not a pointer.)
With this fix, the test case in
https://github.com/llvm/llvm-project/issues/107784
no longer experiences semantic errors; however, it now crashes unexpectedly in lowering.
---
Full diff: https://github.com/llvm/llvm-project/pull/107928.diff
6 Files Affected:
- (modified) flang/include/flang/Semantics/scope.h (+2)
- (modified) flang/lib/Semantics/compute-offsets.cpp (+7)
- (modified) flang/lib/Semantics/expression.cpp (+6-1)
- (modified) flang/lib/Semantics/resolve-names.cpp (+58-11)
- (modified) flang/lib/Semantics/symbol.cpp (+2-1)
- (added) flang/test/Semantics/generic10.f90 (+17)
``````````diff
diff --git a/flang/include/flang/Semantics/scope.h b/flang/include/flang/Semantics/scope.h
index a58163f5460c25..e73a507e9b3f5b 100644
--- a/flang/include/flang/Semantics/scope.h
+++ b/flang/include/flang/Semantics/scope.h
@@ -138,6 +138,8 @@ class Scope {
const_iterator cend() const { return symbols_.cend(); }
// Return symbols in declaration order (the iterators above are in name order)
+ // When a generic procedure interface shadows a derived type or specific
+ // procedure, only the generic's symbol appears in the output.
SymbolVector GetSymbols() const;
MutableSymbolVector GetSymbols();
diff --git a/flang/lib/Semantics/compute-offsets.cpp b/flang/lib/Semantics/compute-offsets.cpp
index d9a9576e9d676a..b5a58ddca0ecdd 100644
--- a/flang/lib/Semantics/compute-offsets.cpp
+++ b/flang/lib/Semantics/compute-offsets.cpp
@@ -114,6 +114,13 @@ void ComputeOffsetsHelper::Compute(Scope &scope) {
dependents_.find(symbol) == dependents_.end() &&
equivalenceBlock_.find(symbol) == equivalenceBlock_.end()) {
DoSymbol(*symbol);
+ if (auto *generic{symbol->detailsIf<GenericDetails>()}) {
+ if (Symbol * specific{generic->specific()};
+ specific && !FindCommonBlockContaining(*specific)) {
+ // might be a shadowed procedure pointer
+ DoSymbol(*specific);
+ }
+ }
}
}
// Ensure that the size is a multiple of the alignment
diff --git a/flang/lib/Semantics/expression.cpp b/flang/lib/Semantics/expression.cpp
index 3684839c187e68..5e4174a557af65 100644
--- a/flang/lib/Semantics/expression.cpp
+++ b/flang/lib/Semantics/expression.cpp
@@ -210,7 +210,8 @@ class ArgumentAnalyzer {
// or procedure pointer reference in a ProcedureDesignator.
MaybeExpr ExpressionAnalyzer::Designate(DataRef &&ref) {
const Symbol &last{ref.GetLastSymbol()};
- const Symbol &symbol{BypassGeneric(last).GetUltimate()};
+ const Symbol &specific{BypassGeneric(last)};
+ const Symbol &symbol{specific.GetUltimate()};
if (semantics::IsProcedure(symbol)) {
if (symbol.attrs().test(semantics::Attr::ABSTRACT)) {
Say("Abstract procedure interface '%s' may not be used as a designator"_err_en_US,
@@ -226,6 +227,10 @@ MaybeExpr ExpressionAnalyzer::Designate(DataRef &&ref) {
} else if (!symbol.attrs().test(semantics::Attr::INTRINSIC)) {
if (symbol.has<semantics::GenericDetails>()) {
Say("'%s' is not a specific procedure"_err_en_US, last.name());
+ } else if (IsProcedurePointer(specific)) {
+ // For procedure pointers, retain associations so that data accesses
+ // from client modules will work.
+ return Expr<SomeType>{ProcedureDesignator{specific}};
} else {
return Expr<SomeType>{ProcedureDesignator{symbol}};
}
diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index 2e86e0afc9bd0e..a2bdeb39901553 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -618,6 +618,20 @@ class ScopeHandler : public ImplicitRulesVisitor {
return *derivedType;
}
}
+ } else if constexpr (std::is_same_v<ProcEntityDetails, D>) {
+ if (auto *d{symbol->detailsIf<GenericDetails>()}) {
+ if (!d->derivedType()) {
+ // procedure pointer with same name as a generic
+ auto *specific{d->specific()};
+ if (!specific) {
+ specific = &currScope().MakeSymbol(name, attrs, std::move(details));
+ d->set_specific(*specific);
+ } else {
+ SayAlreadyDeclared(name, *specific);
+ }
+ return *specific;
+ }
+ }
}
if (symbol->CanReplaceDetails(details)) {
// update the existing symbol
@@ -3035,14 +3049,26 @@ void ModuleVisitor::DoAddUse(SourceName location, SourceName localName,
return;
}
const Symbol &useUltimate{useSymbol.GetUltimate()};
+ const auto *useGeneric{useUltimate.detailsIf<GenericDetails>()};
if (localSymbol->has<UnknownDetails>()) {
- localSymbol->set_details(UseDetails{localName, useSymbol});
- localSymbol->attrs() =
- useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE, Attr::SAVE};
- localSymbol->implicitAttrs() =
- localSymbol->attrs() & Attrs{Attr::ASYNCHRONOUS, Attr::VOLATILE};
- localSymbol->flags() = useSymbol.flags();
- return;
+ if (useGeneric && useGeneric->specific() &&
+ IsProcedurePointer(*useGeneric->specific())) {
+ // We are use-associating a generic that shadows a procedure pointer.
+ // Local references that might be made to that procedure pointer should
+ // use a UseDetails symbol for proper data addressing. So create an
+ // empty local generic now into which the use-associated generic may
+ // be copied.
+ localSymbol->set_details(GenericDetails{});
+ localSymbol->get<GenericDetails>().set_kind(useGeneric->kind());
+ } else { // just create UseDetails
+ localSymbol->set_details(UseDetails{localName, useSymbol});
+ localSymbol->attrs() =
+ useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE, Attr::SAVE};
+ localSymbol->implicitAttrs() =
+ localSymbol->attrs() & Attrs{Attr::ASYNCHRONOUS, Attr::VOLATILE};
+ localSymbol->flags() = useSymbol.flags();
+ return;
+ }
}
Symbol &localUltimate{localSymbol->GetUltimate()};
@@ -3066,10 +3092,7 @@ void ModuleVisitor::DoAddUse(SourceName location, SourceName localName,
// - anything other than a derived type, non-generic procedure, or
// generic procedure being combined with something other than an
// prior USE association of itself
-
auto *localGeneric{localUltimate.detailsIf<GenericDetails>()};
- const auto *useGeneric{useUltimate.detailsIf<GenericDetails>()};
-
Symbol *localDerivedType{nullptr};
if (localUltimate.has<DerivedTypeDetails>()) {
localDerivedType = &localUltimate;
@@ -3261,6 +3284,15 @@ void ModuleVisitor::DoAddUse(SourceName location, SourceName localName,
// At this point, there must be at least one generic interface.
CHECK(localGeneric || (useGeneric && (localDerivedType || localProcedure)));
+ // Ensure that a use-associated specific procedure that is a procedure
+ // pointer is properly represented as a USE association of an entity.
+ if (IsProcedurePointer(useProcedure)) {
+ Symbol &combined{currScope().MakeSymbol(localSymbol->name(),
+ useProcedure->attrs(), UseDetails{localName, *useProcedure})};
+ combined.flags() |= useProcedure->flags();
+ combinedProcedure = &combined;
+ }
+
if (localGeneric) {
// Create a local copy of a previously use-associated generic so that
// it can be locally extended without corrupting the original.
@@ -5079,7 +5111,22 @@ bool DeclarationVisitor::HasCycle(
Symbol &DeclarationVisitor::DeclareProcEntity(
const parser::Name &name, Attrs attrs, const Symbol *interface) {
- Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
+ Symbol *proc{nullptr};
+ if (auto *extant{FindInScope(name)}) {
+ if (auto *d{extant->detailsIf<GenericDetails>()}; d && !d->derivedType()) {
+ // procedure pointer with same name as a generic
+ if (auto *specific{d->specific()}) {
+ SayAlreadyDeclared(name, *specific);
+ } else {
+ // Create the ProcEntityDetails symbol in the scope as the "specific()"
+ // symbol behind an existing GenericDetails symbol of the same name.
+ proc = &Resolve(name,
+ currScope().MakeSymbol(name.source, attrs, ProcEntityDetails{}));
+ d->set_specific(*proc);
+ }
+ }
+ }
+ Symbol &symbol{proc ? *proc : DeclareEntity<ProcEntityDetails>(name, attrs)};
if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
if (context().HasError(symbol)) {
} else if (HasCycle(symbol, interface)) {
diff --git a/flang/lib/Semantics/symbol.cpp b/flang/lib/Semantics/symbol.cpp
index b593bf89b18bc9..14d6564664f2cc 100644
--- a/flang/lib/Semantics/symbol.cpp
+++ b/flang/lib/Semantics/symbol.cpp
@@ -210,8 +210,9 @@ const Symbol *GenericDetails::CheckSpecific() const {
}
Symbol *GenericDetails::CheckSpecific() {
if (specific_ && !specific_->has<UseErrorDetails>()) {
+ const Symbol &ultimate{specific_->GetUltimate()};
for (const Symbol &proc : specificProcs_) {
- if (&proc == specific_) {
+ if (&proc.GetUltimate() == &ultimate) {
return nullptr;
}
}
diff --git a/flang/test/Semantics/generic10.f90 b/flang/test/Semantics/generic10.f90
new file mode 100644
index 00000000000000..203d0bb855208d
--- /dev/null
+++ b/flang/test/Semantics/generic10.f90
@@ -0,0 +1,17 @@
+! RUN: %flang_fc1 -fdebug-unparse %s 2>&1 | FileCheck %s
+module m
+ procedure(func), pointer :: foo
+ interface foo
+ procedure :: foo
+ end interface
+ contains
+ function func(x)
+ func = x
+ end
+end
+
+program main
+ use m
+!CHECK: foo => func
+ foo => func
+end
``````````
</details>
https://github.com/llvm/llvm-project/pull/107928
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