[flang-commits] [flang] [flang] Relax constraints on PURE/ELEMENTAL dummy arguments (PR #93748)
via flang-commits
flang-commits at lists.llvm.org
Wed May 29 16:23:05 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-flang-semantics
Author: Peter Klausler (klausler)
<details>
<summary>Changes</summary>
The standard requires that dummy arguments to PURE functions be INTENT(IN) or VALUE, but PURE subroutines are allowed to have modifiable dummy arguments. This makes it impossible to declare atomic operations as PURE functions, which consequently makes such atomic operations ineligible for use in parallel constructs and DO CONCURRENT.
This patch downgrades this error to a warning by default, which can be seen with -pedantic & al. and remain an error with -Werror.
---
Full diff: https://github.com/llvm/llvm-project/pull/93748.diff
5 Files Affected:
- (modified) flang/docs/Extensions.md (+6)
- (modified) flang/include/flang/Common/Fortran-features.h (+1-1)
- (modified) flang/lib/Semantics/check-declarations.cpp (+49-12)
- (modified) flang/test/Semantics/call10.f90 (+4-4)
- (modified) flang/test/Semantics/elemental01.f90 (+2-2)
``````````diff
diff --git a/flang/docs/Extensions.md b/flang/docs/Extensions.md
index 7b872c786c82c..bbda7c2aa2541 100644
--- a/flang/docs/Extensions.md
+++ b/flang/docs/Extensions.md
@@ -118,6 +118,12 @@ end
procedure interface. This compiler accepts it, since there is otherwise
no way to declare an interoperable dummy procedure with an arbitrary
interface like `void (*)()`.
+* `PURE` functions are allowed to have dummy arguments that are
+ neither `INTENT(IN)` nor `VALUE`, similar to `PURE` subroutines,
+ with a warning.
+ This enables atomic memory operations to be naturally represented
+ as `PURE` functions, which allows their use in parallel constructs
+ and `DO CONCURRENT`.
## Extensions, deletions, and legacy features supported by default
diff --git a/flang/include/flang/Common/Fortran-features.h b/flang/include/flang/Common/Fortran-features.h
index 15c4af63f4be7..fcd44bf68c9b2 100644
--- a/flang/include/flang/Common/Fortran-features.h
+++ b/flang/include/flang/Common/Fortran-features.h
@@ -50,7 +50,7 @@ ENUM_CLASS(LanguageFeature, BackslashEscapes, OldDebugLines,
EmptySequenceType, NonSequenceCrayPointee, BranchIntoConstruct,
BadBranchTarget, ConvertedArgument, HollerithPolymorphic, ListDirectedSize,
NonBindCInteroperability, CudaManaged, CudaUnified,
- PolymorphicActualAllocatableOrPointerToMonomorphicDummy)
+ PolymorphicActualAllocatableOrPointerToMonomorphicDummy, RelaxedPureDummy)
// Portability and suspicious usage warnings
ENUM_CLASS(UsageWarning, Portability, PointerToUndefinable,
diff --git a/flang/lib/Semantics/check-declarations.cpp b/flang/lib/Semantics/check-declarations.cpp
index 7034902dcc58d..1b3e00ad3b402 100644
--- a/flang/lib/Semantics/check-declarations.cpp
+++ b/flang/lib/Semantics/check-declarations.cpp
@@ -704,29 +704,58 @@ void CheckHelper::CheckObjectEntity(
if (InPure() && !IsStmtFunction(DEREF(innermostSymbol_)) &&
!IsPointer(symbol) && !IsIntentIn(symbol) &&
!symbol.attrs().test(Attr::VALUE)) {
- if (InFunction()) { // C1583
- messages_.Say(
- "non-POINTER dummy argument of pure function must be INTENT(IN) or VALUE"_err_en_US);
- } else if (IsIntentOut(symbol)) {
+ const char *what{InFunction() ? "function" : "subroutine"};
+ bool ok{true};
+ if (IsIntentOut(symbol)) {
if (type && type->IsPolymorphic()) { // C1588
messages_.Say(
- "An INTENT(OUT) dummy argument of a pure subroutine may not be polymorphic"_err_en_US);
+ "An INTENT(OUT) dummy argument of a pure %s may not be polymorphic"_err_en_US,
+ what);
+ ok = false;
} else if (derived) {
if (FindUltimateComponent(*derived, [](const Symbol &x) {
const DeclTypeSpec *type{x.GetType()};
return type && type->IsPolymorphic();
})) { // C1588
messages_.Say(
- "An INTENT(OUT) dummy argument of a pure subroutine may not have a polymorphic ultimate component"_err_en_US);
+ "An INTENT(OUT) dummy argument of a pure %s may not have a polymorphic ultimate component"_err_en_US,
+ what);
+ ok = false;
}
if (HasImpureFinal(symbol)) { // C1587
messages_.Say(
- "An INTENT(OUT) dummy argument of a pure subroutine may not have an impure FINAL subroutine"_err_en_US);
+ "An INTENT(OUT) dummy argument of a pure %s may not have an impure FINAL subroutine"_err_en_US,
+ what);
+ ok = false;
}
}
} else if (!IsIntentInOut(symbol)) { // C1586
- messages_.Say(
- "non-POINTER dummy argument of pure subroutine must have INTENT() or VALUE attribute"_err_en_US);
+ if (context_.IsEnabled(common::LanguageFeature::RelaxedPureDummy)) {
+ if (context_.ShouldWarn(common::LanguageFeature::RelaxedPureDummy) &&
+ !InModuleFile() && !InElemental()) {
+ messages_.Say(
+ "non-POINTER dummy argument of pure %s should have INTENT() or VALUE attribute"_warn_en_US,
+ what);
+ ok = false;
+ }
+ } else {
+ messages_.Say(
+ "non-POINTER dummy argument of pure %s must have INTENT() or VALUE attribute"_warn_en_US,
+ what);
+ ok = false;
+ }
+ }
+ if (ok && InFunction()) {
+ if (context_.IsEnabled(common::LanguageFeature::RelaxedPureDummy)) {
+ if (context_.ShouldWarn(common::LanguageFeature::RelaxedPureDummy) &&
+ !InModuleFile() && !InElemental()) {
+ messages_.Say(
+ "non-POINTER dummy argument of pure function should be INTENT(IN) or VALUE"_warn_en_US);
+ }
+ } else {
+ messages_.Say(
+ "non-POINTER dummy argument of pure function must be INTENT(IN) or VALUE"_err_en_US);
+ }
}
}
if (auto ignoreTKR{GetIgnoreTKR(symbol)}; !ignoreTKR.empty()) {
@@ -798,9 +827,17 @@ void CheckHelper::CheckObjectEntity(
"A dummy argument of an ELEMENTAL procedure may not be a POINTER"_err_en_US);
}
if (!symbol.attrs().HasAny(Attrs{Attr::VALUE, Attr::INTENT_IN,
- Attr::INTENT_INOUT, Attr::INTENT_OUT})) { // C15102
- messages_.Say(
- "A dummy argument of an ELEMENTAL procedure must have an INTENT() or VALUE attribute"_err_en_US);
+ Attr::INTENT_INOUT, Attr::INTENT_OUT})) { // F'2023 C15120
+ if (context_.IsEnabled(common::LanguageFeature::RelaxedPureDummy)) {
+ if (context_.ShouldWarn(common::LanguageFeature::RelaxedPureDummy) &&
+ !InModuleFile()) {
+ messages_.Say(
+ "A dummy argument of an ELEMENTAL procedure should have an INTENT() or VALUE attribute"_warn_en_US);
+ }
+ } else {
+ messages_.Say(
+ "A dummy argument of an ELEMENTAL procedure must have an INTENT() or VALUE attribute"_err_en_US);
+ }
}
} else if (IsFunctionResult(symbol)) { // C15101
if (details.shape().Rank() > 0) {
diff --git a/flang/test/Semantics/call10.f90 b/flang/test/Semantics/call10.f90
index b1f3528227497..6b02bc63ac325 100644
--- a/flang/test/Semantics/call10.f90
+++ b/flang/test/Semantics/call10.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
! Test 15.7 (C1583-C1590, C1592-C1599) constraints and restrictions
! for pure procedures.
! (C1591 is tested in call11.f90; C1594 in call12.f90.)
@@ -53,14 +53,14 @@ pure real function f02(a)
real, value :: a ! ok
end function
pure real function f03(a) ! C1583
- !ERROR: non-POINTER dummy argument of pure function must be INTENT(IN) or VALUE
+ !ERROR: non-POINTER dummy argument of pure function should have INTENT() or VALUE attribute
real :: a
end function
pure real function f03a(a)
real, pointer :: a ! ok
end function
pure real function f04(a) ! C1583
- !ERROR: non-POINTER dummy argument of pure function must be INTENT(IN) or VALUE
+ !WARNING: non-POINTER dummy argument of pure function should be INTENT(IN) or VALUE
real, intent(out) :: a
end function
pure real function f04a(a)
@@ -83,7 +83,7 @@ pure function f08() ! C1585
end function
pure subroutine s01(a) ! C1586
- !ERROR: non-POINTER dummy argument of pure subroutine must have INTENT() or VALUE attribute
+ !WARNING: non-POINTER dummy argument of pure subroutine should have INTENT() or VALUE attribute
real :: a
end subroutine
pure subroutine s01a(a)
diff --git a/flang/test/Semantics/elemental01.f90 b/flang/test/Semantics/elemental01.f90
index 8a80727da45ef..19c112fe045b2 100644
--- a/flang/test/Semantics/elemental01.f90
+++ b/flang/test/Semantics/elemental01.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
! Tests ELEMENTAL subprogram constraints C15100-15102
!ERROR: An ELEMENTAL subroutine may not have an alternate return dummy argument
@@ -26,7 +26,7 @@ elemental subroutine ptrarg(a)
end subroutine
impure elemental subroutine barearg(a)
- !ERROR: A dummy argument of an ELEMENTAL procedure must have an INTENT() or VALUE attribute
+ !WARNING: A dummy argument of an ELEMENTAL procedure should have an INTENT() or VALUE attribute
real :: a
end subroutine
``````````
</details>
https://github.com/llvm/llvm-project/pull/93748
More information about the flang-commits
mailing list