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[flang] Further refine errors vs warnings for ambiguous generics #80161

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Merged
merged 1 commit into from
Feb 20, 2024
Merged

[flang] Further refine errors vs warnings for ambiguous generics #80161

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44 changes: 29 additions & 15 deletions flang/lib/Semantics/check-declarations.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -192,7 +192,7 @@ class DistinguishabilityHelper {

private:
void SayNotDistinguishable(const Scope &, const SourceName &, GenericKind,
const Symbol &, const Symbol &, bool isError);
const Symbol &, const Symbol &, bool isHardConflict);
void AttachDeclaration(parser::Message &, const Scope &, const Symbol &);

SemanticsContext &context_;
Expand Down Expand Up @@ -3513,6 +3513,11 @@ void DistinguishabilityHelper::Add(const Symbol &generic, GenericKind kind,
}

void DistinguishabilityHelper::Check(const Scope &scope) {
if (FindModuleFileContaining(scope)) {
// Distinguishability was checked when the module was created;
// don't let optional warnings then become errors now.
return;
}
for (const auto &[name, info] : nameToSpecifics_) {
for (auto iter1{info.begin()}; iter1 != info.end(); ++iter1) {
const auto &[ultimate, procInfo]{*iter1};
Expand All @@ -3534,15 +3539,21 @@ void DistinguishabilityHelper::Check(const Scope &scope) {

void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
const SourceName &name, GenericKind kind, const Symbol &proc1,
const Symbol &proc2, bool isError) {
if (!isError &&
!context_.ShouldWarn(
common::LanguageFeature::IndistinguishableSpecifics)) {
// The rules for distinguishing specific procedures (F'2023 15.4.3.4.5)
// are inadequate for some real-world cases like pFUnit.
// When there are optional dummy arguments or unlimited polymorphic
// dummy data object arguments, the best that we can do is emit an optional
// portability warning.
const Symbol &proc2, bool isHardConflict) {
bool isUseAssociated{!scope.sourceRange().Contains(name)};
// The rules for distinguishing specific procedures (F'2023 15.4.3.4.5)
// are inadequate for some real-world cases like pFUnit.
// When there are optional dummy arguments or unlimited polymorphic
// dummy data object arguments, the best that we can do is emit an optional
// portability warning. Also, named generics created by USE association
// merging shouldn't receive hard errors for ambiguity.
// (Non-named generics might be defined I/O procedures or defined
// assignments that need to be used by the runtime.)
bool isWarning{!isHardConflict || (isUseAssociated && kind.IsName())};
if (isWarning &&
(!context_.ShouldWarn(
common::LanguageFeature::IndistinguishableSpecifics) ||
FindModuleFileContaining(scope))) {
return;
}
std::string name1{proc1.name().ToString()};
Expand All @@ -3557,17 +3568,20 @@ void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
}
}
parser::Message *msg;
if (scope.sourceRange().Contains(name)) {
if (!isUseAssociated) {
CHECK(isWarning == !isHardConflict);
msg = &context_.Say(name,
isError
isHardConflict
? "Generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US
: "Generic '%s' should not have specific procedures '%s' and '%s' as their interfaces are not distinguishable by the rules in the standard"_port_en_US,
MakeOpName(name), name1, name2);
} else {
msg = &context_.Say(*GetTopLevelUnitContaining(proc1).GetName(),
isError
? "USE-associated generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US
: "USE-associated generic '%s' should not have specific procedures '%s' and '%s' as their interfaces are not distinguishable by the incomplete rules in the standard"_port_en_US,
isHardConflict
? (isWarning
? "USE-associated generic '%s' should not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_warn_en_US
: "USE-associated generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US)
: "USE-associated generic '%s' should not have specific procedures '%s' and '%s' as their interfaces are not distinguishable by the rules in the standard"_port_en_US,
MakeOpName(name), name1, name2);
}
AttachDeclaration(*msg, scope, proc1);
Expand Down
2 changes: 1 addition & 1 deletion flang/test/Semantics/resolve17.f90
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Expand Up @@ -180,7 +180,7 @@ subroutine g()
end
end module
subroutine s9
!ERROR: USE-associated generic 'g' may not have specific procedures 'g' and 'g' as their interfaces are not distinguishable
!PORTABILITY: USE-associated generic 'g' should not have specific procedures 'g' and 'g' as their interfaces are not distinguishable
use m9a
use m9b
end
Expand Down