[flang] Finer error detection in separate module procedure case #110912
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When a separate module procedure has a dummy procedure argument that is simply declared EXTERNAL in its interface but is actually called as a subroutine or function in its definition, the compiler is emitting an error message. This is too strong; an error is appropriate only when the dummy procedure in the definition has an interface that is incompatible with the one in the interface definition. However, this is not a safe coding practice, and can lead to trouble during execution if a function is passed as an actual argument but called as a subroutine in the procedure (or the other way around), so add a warning message as well for this case (off by default). Fixes llvm#110797.
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@llvm/pr-subscribers-flang-semantics Author: Peter Klausler (klausler) ChangesWhen a separate module procedure has a dummy procedure argument that is simply declared EXTERNAL in its interface but is actually called as a subroutine or function in its definition, the compiler is emitting an error message. This is too strong; an error is appropriate only when the dummy procedure in the definition has an interface that is incompatible with the one in the interface definition. However, this is not a safe coding practice, and can lead to trouble during execution if a function is passed as an actual argument but called as a subroutine in the procedure (or the other way around), so add a warning message as well for this case (off by default). Fixes #110797. Full diff: https://github.com/llvm/llvm-project/pull/110912.diff 3 Files Affected:
diff --git a/flang/include/flang/Common/Fortran-features.h b/flang/include/flang/Common/Fortran-features.h
index f813cbae40a57e..3942a792628645 100644
--- a/flang/include/flang/Common/Fortran-features.h
+++ b/flang/include/flang/Common/Fortran-features.h
@@ -72,7 +72,8 @@ ENUM_CLASS(UsageWarning, Portability, PointerToUndefinable,
IgnoredIntrinsicFunctionType, PreviousScalarUse,
RedeclaredInaccessibleComponent, ImplicitShared, IndexVarRedefinition,
IncompatibleImplicitInterfaces, BadTypeForTarget,
- VectorSubscriptFinalization, UndefinedFunctionResult, UselessIomsg)
+ VectorSubscriptFinalization, UndefinedFunctionResult, UselessIomsg,
+ MismatchingDummyProcedure)
using LanguageFeatures = EnumSet<LanguageFeature, LanguageFeature_enumSize>;
using UsageWarnings = EnumSet<UsageWarning, UsageWarning_enumSize>;
diff --git a/flang/lib/Semantics/check-declarations.cpp b/flang/lib/Semantics/check-declarations.cpp
index 7778561fb5bd33..f8e873008ceabc 100644
--- a/flang/lib/Semantics/check-declarations.cpp
+++ b/flang/lib/Semantics/check-declarations.cpp
@@ -3765,12 +3765,20 @@ void SubprogramMatchHelper::CheckDummyDataObject(const Symbol &symbol1,
void SubprogramMatchHelper::CheckDummyProcedure(const Symbol &symbol1,
const Symbol &symbol2, const DummyProcedure &proc1,
const DummyProcedure &proc2) {
+ std::string whyNot;
if (!CheckSameIntent(symbol1, symbol2, proc1.intent, proc2.intent)) {
} else if (!CheckSameAttrs(symbol1, symbol2, proc1.attrs, proc2.attrs)) {
- } else if (proc1 != proc2) {
+ } else if (!proc2.IsCompatibleWith(proc1, &whyNot)) {
Say(symbol1, symbol2,
- "Dummy procedure '%s' does not match the corresponding argument in"
- " the interface body"_err_en_US);
+ "Dummy procedure '%s' is not compatible with the corresponding argument in the interface body: %s"_err_en_US,
+ whyNot);
+ } else if (proc1 != proc2) {
+ evaluate::AttachDeclaration(
+ symbol1.owner().context().Warn(
+ common::UsageWarning::MismatchingDummyProcedure,
+ "Dummy procedure '%s' does not exactly match the corresponding argument in the interface body"_warn_en_US,
+ symbol1.name()),
+ symbol2);
}
}
diff --git a/flang/test/Semantics/separate-mp02.f90 b/flang/test/Semantics/separate-mp02.f90
index c63ab6f41a1326..cb1e2687bad736 100644
--- a/flang/test/Semantics/separate-mp02.f90
+++ b/flang/test/Semantics/separate-mp02.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
! When a module subprogram has the MODULE prefix the following must match
! with the corresponding separate module procedure interface body:
@@ -238,7 +238,7 @@ module subroutine s1(x)
procedure(s_real2) :: x
end
module subroutine s2(x)
- !ERROR: Dummy procedure 'x' does not match the corresponding argument in the interface body
+ !ERROR: Dummy procedure 'x' is not compatible with the corresponding argument in the interface body: incompatible dummy procedure interfaces: incompatible dummy argument #1: incompatible dummy data object types: INTEGER(4) vs REAL(4)
procedure(s_integer) :: x
end
end
@@ -357,3 +357,19 @@ module character(2) function f()
module character(3) function f()
end function
end submodule
+
+module m11
+ interface
+ module subroutine s(x)
+ ! The subroutine/function distinction is not known.
+ external x
+ end
+ end interface
+end
+submodule(m11) sm11
+ contains
+ !WARNING: Dummy procedure 'x' does not exactly match the corresponding argument in the interface body
+ module subroutine s(x)
+ call x ! no error
+ end
+end
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vdonaldson
approved these changes
Oct 2, 2024
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When a separate module procedure has a dummy procedure argument that is simply declared EXTERNAL in its interface but is actually called as a subroutine or function in its definition, the compiler is emitting an error message. This is too strong; an error is appropriate only when the dummy procedure in the definition has an interface that is incompatible with the one in the interface definition.
However, this is not a safe coding practice, and can lead to trouble during execution if a function is passed as an actual argument but called as a subroutine in the procedure (or the other way around), so add a warning message as well for this case (off by default).
Fixes #110797.