[flang] Warn on useless IOMSG= (llvm#102250)

An I/O statement with IOMSG= but neither ERR= nor IOSTAT= deserves a warning to the effect that it's not useful.
ROCm · Aug 8, 2024 · b949a6f · b949a6f
1 parent 245eb0a
commit b949a6f
Show file tree

Hide file tree

Showing 6 changed files with 28 additions and 2 deletions.
diff --git a/flang/include/flang/Common/Fortran-features.h b/flang/include/flang/Common/Fortran-features.h
@@ -70,7 +70,7 @@ ENUM_CLASS(UsageWarning, Portability, PointerToUndefinable,
  IgnoredIntrinsicFunctionType, PreviousScalarUse,
  RedeclaredInaccessibleComponent, ImplicitShared, IndexVarRedefinition,
  IncompatibleImplicitInterfaces, BadTypeForTarget,
- VectorSubscriptFinalization, UndefinedFunctionResult)
+ VectorSubscriptFinalization, UndefinedFunctionResult, UselessIomsg)
 
 using LanguageFeatures = EnumSet<LanguageFeature, LanguageFeature_enumSize>;
 using UsageWarnings = EnumSet<UsageWarning, UsageWarning_enumSize>;
@@ -145,6 +145,7 @@ class LanguageFeatureControl {
  warnUsage_.set(UsageWarning::BadTypeForTarget);
  warnUsage_.set(UsageWarning::VectorSubscriptFinalization);
  warnUsage_.set(UsageWarning::UndefinedFunctionResult);
+ warnUsage_.set(UsageWarning::UselessIomsg);
  }
  LanguageFeatureControl(const LanguageFeatureControl &) = default;
 

diff --git a/flang/lib/Semantics/check-io.cpp b/flang/lib/Semantics/check-io.cpp
@@ -675,27 +675,31 @@ void IoChecker::Leave(const parser::BackspaceStmt &) {
  CheckForPureSubprogram();
  CheckForRequiredSpecifier(
  flags_.test(Flag::NumberUnit), "UNIT number"); // C1240
+ CheckForUselessIomsg();
  Done();
 }
 
 void IoChecker::Leave(const parser::CloseStmt &) {
  CheckForPureSubprogram();
  CheckForRequiredSpecifier(
  flags_.test(Flag::NumberUnit), "UNIT number"); // C1208
+ CheckForUselessIomsg();
  Done();
 }
 
 void IoChecker::Leave(const parser::EndfileStmt &) {
  CheckForPureSubprogram();
  CheckForRequiredSpecifier(
  flags_.test(Flag::NumberUnit), "UNIT number"); // C1240
+ CheckForUselessIomsg();
  Done();
 }
 
 void IoChecker::Leave(const parser::FlushStmt &) {
  CheckForPureSubprogram();
  CheckForRequiredSpecifier(
  flags_.test(Flag::NumberUnit), "UNIT number"); // C1243
+ CheckForUselessIomsg();
  Done();
 }
 
@@ -708,6 +712,7 @@ void IoChecker::Leave(const parser::InquireStmt &stmt) {
  "UNIT number or FILE"); // C1246
  CheckForProhibitedSpecifier(IoSpecKind::File, IoSpecKind::Unit); // C1246
  CheckForRequiredSpecifier(IoSpecKind::Id, IoSpecKind::Pending); // C1248
+ CheckForUselessIomsg();
  }
  Done();
 }
@@ -742,11 +747,13 @@ void IoChecker::Leave(const parser::OpenStmt &) {
  CheckForProhibitedSpecifier(flags_.test(Flag::AccessStream),
  "STATUS='STREAM'", IoSpecKind::Recl); // 12.5.6.15
  }
+ CheckForUselessIomsg();
  Done();
 }
 
 void IoChecker::Leave(const parser::PrintStmt &) {
  CheckForPureSubprogram();
+ CheckForUselessIomsg();
  Done();
 }
 
@@ -817,13 +824,15 @@ void IoChecker::Leave(const parser::RewindStmt &) {
  CheckForRequiredSpecifier(
  flags_.test(Flag::NumberUnit), "UNIT number"); // C1240
  CheckForPureSubprogram();
+ CheckForUselessIomsg();
  Done();
 }
 
 void IoChecker::Leave(const parser::WaitStmt &) {
  CheckForRequiredSpecifier(
  flags_.test(Flag::NumberUnit), "UNIT number"); // C1237
  CheckForPureSubprogram();
+ CheckForUselessIomsg();
  Done();
 }
 
@@ -883,6 +892,7 @@ void IoChecker::LeaveReadWrite() const {
  "FMT or NML"); // C1227
  CheckForRequiredSpecifier(IoSpecKind::Round, flags_.test(Flag::FmtOrNml),
  "FMT or NML"); // C1227
+ CheckForUselessIomsg();
 }
 
 void IoChecker::SetSpecifier(IoSpecKind specKind) {
@@ -1057,6 +1067,15 @@ void IoChecker::CheckForPureSubprogram() const { // C1597
  }
 }
 
+void IoChecker::CheckForUselessIomsg() const {
+ if (specifierSet_.test(IoSpecKind::Iomsg) &&
+ !specifierSet_.test(IoSpecKind::Err) &&
+ !specifierSet_.test(IoSpecKind::Iostat) &&
+ context_.ShouldWarn(common::UsageWarning::UselessIomsg)) {
+ context_.Say("IOMSG= is useless without either ERR= or IOSTAT="_warn_en_US);
+ }
+}
+
 // Seeks out an allocatable or pointer ultimate component that is not
 // nested in a nonallocatable/nonpointer component with a specific
 // defined I/O procedure.

diff --git a/flang/lib/Semantics/check-io.h b/flang/lib/Semantics/check-io.h
@@ -125,6 +125,7 @@ class IoChecker : public virtual BaseChecker {
  void CheckForDefinableVariable(const A &var, const std::string &s) const;
 
  void CheckForPureSubprogram() const;
+ void CheckForUselessIomsg() const;
 
  parser::Message *CheckForBadIoType(const evaluate::DynamicType &,
  common::DefinedIo, parser::CharBlock) const;

diff --git a/flang/lib/Semantics/semantics.cpp b/flang/lib/Semantics/semantics.cpp
@@ -221,10 +221,13 @@ static bool PerformStatementSemantics(
  if (context.languageFeatures().IsEnabled(common::LanguageFeature::CUDA)) {
  SemanticsVisitor<CUDAChecker>{context}.Walk(program);
  }
- if (!context.AnyFatalError()) {
+ if (!context.messages().AnyFatalError()) {
+ // Do this if all messages are only warnings
  if (context.ShouldWarn(common::UsageWarning::UndefinedFunctionResult)) {
  WarnUndefinedFunctionResult(context, context.globalScope());
  }
+ }
+ if (!context.AnyFatalError()) {
  pass2.CompileDataInitializationsIntoInitializers();
  }
  return !context.AnyFatalError();

diff --git a/flang/test/Semantics/io05.f90 b/flang/test/Semantics/io05.f90
@@ -55,6 +55,7 @@
  inquire(1, read=c(1), write=c(2), sign=c(3), sign=c(4), read=c(5), write=c(1))
 
  !ERROR: Duplicate IOMSG specifier
+ !WARNING: IOMSG= is useless without either ERR= or IOSTAT=
  inquire(10, iomsg=msg, pos=ipos, iomsg=msg)
 
  !ERROR: If ID appears, PENDING must also appear

diff --git a/flang/test/Semantics/undef-result01.f90 b/flang/test/Semantics/undef-result01.f90
@@ -121,6 +121,7 @@ integer function defdBySize()
 end
 
 character(40) function defdByIomsg()
+ !WARNING: IOMSG= is useless without either ERR= or IOSTAT=
  write(123,*,iomsg=defdByIomsg)
 end