[flang] Turn "error" cases into warning for "indistinguishable" specific procedures (#79621)

When a generic procedure interface, either declared or the result of merging two use-associated generics, has two specific procedures that are not distinguishable according to the rules in F'2023 subclause 15.4.3.4.5, emit a portability warning rather than a hard error message. The rules in that subclause are not adequate to detect pairs of specific procedures that admit an ambiguous reference, as demonstrated by a case that arose in pFUnit. Further, these distinguishability checks, even if sufficient to the task of detecting pairs of specifics capable of ambiguous references, should only apply to pairs where *every* reference would have to be ambiguous -- and this can and is validated at every reference anyway. Last, only XLF enforces these incomplete and needless distinguishability rules -- every other compiler seems to just check that each procedure reference resolves to exactly one specific procedure. If the standard were to complete lose subclause 15.4.3.4.5 and its related note (C.11.6) -- which admits that the rules are incomplete! -- and simply require that each generic procedure reference resolve unambiguously to exactly one specific, nobody would miss them. This patch changes this compiler to give them lip service when requested, but they are now otherwise ignored.
2026-01-21 12:19:23 +08:00 · 2024-01-29 14:36:37 -08:00
parent d83c977147
commit 37180ed743
13 changed files with 99 additions and 60 deletions
--- a/flang/docs/Extensions.md
+++ b/flang/docs/Extensions.md
@@ -113,6 +113,13 @@ end
  in F'2023 subclause 19.4 paragraphs 6 & 8 should apply.  Since this
  compiler properly scopes these names, violations of these restrictions
  elicit only portability warnings by default.
+* The rules for pairwise distinguishing the specific procedures of a
+  generic interface are inadequate, as admitted in note C.11.6 of F'2023.
+  Generic interfaces whose specific procedures can be easily proven by
+  hand to be pairwise distinct (i.e., no ambiguous reference is possible)
+  appear in real applications, but are still non-conforming under the
+  incomplete tests in F'2023 15.4.3.4.5.
+  These cases are compiled with optional portability warnings.

 ## Extensions, deletions, and legacy features supported by default

--- a/flang/include/flang/Common/Fortran-features.h
+++ b/flang/include/flang/Common/Fortran-features.h
@@ -45,7 +45,8 @@ ENUM_CLASS(LanguageFeature, BackslashEscapes, OldDebugLines,
    MiscSourceExtensions, AllocateToOtherLength, LongNames, IntrinsicAsSpecific,
    BenignNameClash, BenignRedundancy, NullMoldAllocatableComponentValue,
    NopassScalarBase, MiscUseExtensions, ImpliedDoIndexScope,
-    DistinctCommonSizes, OddIndexVariableRestrictions)
+    DistinctCommonSizes, OddIndexVariableRestrictions,
+    IndistinguishableSpecifics)

 // Portability and suspicious usage warnings for conforming code
 ENUM_CLASS(UsageWarning, Portability, PointerToUndefinable,
--- a/flang/lib/Semantics/check-declarations.cpp
+++ b/flang/lib/Semantics/check-declarations.cpp
@@ -3532,6 +3532,16 @@ void DistinguishabilityHelper::Check(const Scope &scope) {
 void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
    const SourceName &name, GenericKind kind, const Symbol &proc1,
    const Symbol &proc2) {
+  if (!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, which has
+    // some generic interfaces whose specific procedures are provably
+    // unambiguous, but fail all of the standard's criteria for being
+    // conformably distinct.  So the best we can do here is to emit optional
+    // portability warnings for such cases.
+    return;
+  }
  std::string name1{proc1.name().ToString()};
  std::string name2{proc2.name().ToString()};
  if (kind.IsOperator() || kind.IsAssignment()) {
@@ -3546,11 +3556,11 @@ void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
  parser::Message *msg;
  if (scope.sourceRange().Contains(name)) {
    msg = &context_.Say(name,
-        "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 incomplete rules in the standard"_port_en_US,
        MakeOpName(name), name1, name2);
  } else {
    msg = &context_.Say(*GetTopLevelUnitContaining(proc1).GetName(),
-        "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,
        MakeOpName(name), name1, name2);
  }
  AttachDeclaration(*msg, scope, proc1);
--- a/flang/lib/Semantics/expression.cpp
+++ b/flang/lib/Semantics/expression.cpp
@@ -2644,7 +2644,7 @@ const Symbol &ExpressionAnalyzer::AccessSpecific(
 void ExpressionAnalyzer::EmitGenericResolutionError(
    const Symbol &symbol, bool dueToAmbiguity, bool isSubroutine) {
  Say(dueToAmbiguity
-          ? "One or more actual arguments to the generic procedure '%s' matched multiple specific procedures, perhaps due to use of NULL() without MOLD= or an actual procedure with an implicit interface"_err_en_US
+          ? "The actual arguments to the generic procedure '%s' matched multiple specific procedures, perhaps due to use of NULL() without MOLD= or an actual procedure with an implicit interface"_err_en_US
          : semantics::IsGenericDefinedOp(symbol)
          ? "No specific procedure of generic operator '%s' matches the actual arguments"_err_en_US
          : isSubroutine
--- a/flang/lib/Semantics/mod-file.cpp
+++ b/flang/lib/Semantics/mod-file.cpp
@@ -186,9 +186,12 @@ static void HarvestInitializerSymbols(
    } else if (const auto &generic{symbol->detailsIf<GenericDetails>()};
               generic && generic->derivedType()) {
      const Symbol &dtSym{*generic->derivedType()};
-      CHECK(dtSym.has<DerivedTypeDetails>());
-      if (dtSym.scope()) {
-        HarvestInitializerSymbols(set, *dtSym.scope());
+      if (dtSym.has<DerivedTypeDetails>()) {
+        if (dtSym.scope()) {
+          HarvestInitializerSymbols(set, *dtSym.scope());
+        }
+      } else {
+        CHECK(dtSym.has<UseErrorDetails>());
      }
    } else if (IsNamedConstant(*symbol) || scope.IsDerivedType()) {
      if (const auto *object{symbol->detailsIf<ObjectEntityDetails>()}) {
--- a/flang/test/Semantics/generic05.F90
+++ b/flang/test/Semantics/generic05.F90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
 ! Check for distinguishability of defined I/O procedures defined within
 ! and outside their types.
 module m1
@@ -6,7 +6,7 @@ module m1
    integer n
   contains
    procedure :: readt1a, readt1b
-    !ERROR: Generic 'read(unformatted)' may not have specific procedures 'readt1a' and 'readt1b' as their interfaces are not distinguishable
+    !PORTABILITY: Generic 'read(unformatted)' should not have specific procedures 'readt1a' and 'readt1b' as their interfaces are not distinguishable by the incomplete rules in the standard
    generic :: read(unformatted) => readt1a, readt1b
  end type
  type t2
@@ -15,7 +15,7 @@ module m1
  type t3
    integer n
  end type
-  !ERROR: Generic 'read(unformatted)' may not have specific procedures 'readt2a' and 'readt2b' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'read(unformatted)' should not have specific procedures 'readt2a' and 'readt2b' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface read(unformatted)
    module procedure :: readt1a, readt2a, readt2b, readt3
  end interface
--- a/flang/test/Semantics/generic07.f90
+++ b/flang/test/Semantics/generic07.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic -Werror
 module m1
  type :: t1
    sequence
@@ -74,7 +74,7 @@ program test
  interface distinguishable3
    procedure :: s1a, s1b
  end interface
-  !ERROR: Generic 'indistinguishable' may not have specific procedures 's2b' and 's2a' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'indistinguishable' should not have specific procedures 's2b' and 's2a' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface indistinguishable
    procedure :: s2a, s2b
  end interface
--- a/flang/test/Semantics/resolve17.f90
+++ b/flang/test/Semantics/resolve17.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
 module m
  integer :: foo
  !Note: PGI, Intel, and GNU allow this; NAG and Sun do not
@@ -96,7 +96,7 @@ contains
  end
 end
 subroutine s6
-  !ERROR: Generic 'g' may not have specific procedures 'sa' and 'sb' as their interfaces are not distinguishable
+  !ERROR: Generic 'g' should not have specific procedures 'sa' and 'sb' as their interfaces are not distinguishable by the incomplete rules in the standard
  use m6a, g => gg
  use m6b, g => gg
 end
@@ -180,7 +180,7 @@ contains
  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 by the incomplete rules in the standard
  use m9a
  use m9b
 end
@@ -197,7 +197,7 @@ contains
 end
 module m10b
  use m10a
-  !ERROR: Generic 'g' may not have specific procedures 's' and 's' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g' should not have specific procedures 's' and 's' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g
    module procedure s
  end interface
--- a/flang/test/Semantics/resolve53.f90
+++ b/flang/test/Semantics/resolve53.f90
@@ -1,9 +1,9 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
 ! 15.4.3.4.5 Restrictions on generic declarations
 ! Specific procedures of generic interfaces must be distinguishable.

 module m1
-  !ERROR: Generic 'g' may not have specific procedures 's2' and 's4' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g' should not have specific procedures 's2' and 's4' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g
    procedure s1
    procedure s2
@@ -25,7 +25,7 @@ contains
 end

 module m2
-  !ERROR: Generic 'g' may not have specific procedures 'm2s1' and 'm2s2' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g' should not have specific procedures 'm2s1' and 'm2s2' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g
    subroutine m2s1(x)
    end subroutine
@@ -36,7 +36,7 @@ module m2
 end

 module m3
-  !ERROR: Generic 'g' may not have specific procedures 'm3f1' and 'm3f2' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g' should not have specific procedures 'm3f1' and 'm3f2' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g
    integer function m3f1()
    end function
@@ -79,7 +79,7 @@ end

 module m6
  use m5
-  !ERROR: Generic 'g' may not have specific procedures 'm5s1' and 'm6s4' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g' should not have specific procedures 'm5s1' and 'm6s4' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g
    subroutine m6s4(x)
    end subroutine
@@ -88,9 +88,9 @@ end

 module m7
  use m5
-  !ERROR: Generic 'g' may not have specific procedures 'm5s1' and 'm7s5' as their interfaces are not distinguishable
-  !ERROR: Generic 'g' may not have specific procedures 'm5s2' and 'm7s5' as their interfaces are not distinguishable
-  !ERROR: Generic 'g' may not have specific procedures 'm5s3' and 'm7s5' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g' should not have specific procedures 'm5s1' and 'm7s5' as their interfaces are not distinguishable by the incomplete rules in the standard
+  !PORTABILITY: Generic 'g' should not have specific procedures 'm5s2' and 'm7s5' as their interfaces are not distinguishable by the incomplete rules in the standard
+  !PORTABILITY: Generic 'g' should not have specific procedures 'm5s3' and 'm7s5' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g
    subroutine m7s5(x)
      real x(..)
@@ -100,7 +100,7 @@ end

 ! Two procedures that differ only by attributes are not distinguishable
 module m8
-  !ERROR: Generic 'g' may not have specific procedures 'm8s1' and 'm8s2' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g' should not have specific procedures 'm8s1' and 'm8s2' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g
    pure subroutine m8s1(x)
      real, intent(in) :: x
@@ -112,7 +112,7 @@ module m8
 end

 module m9
-  !ERROR: Generic 'g' may not have specific procedures 'm9s1' and 'm9s2' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g' should not have specific procedures 'm9s1' and 'm9s2' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g
    subroutine m9s1(x)
      real :: x(10)
@@ -124,7 +124,7 @@ module m9
 end

 module m10
-  !ERROR: Generic 'g' may not have specific procedures 'm10s1' and 'm10s2' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g' should not have specific procedures 'm10s1' and 'm10s2' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g
    subroutine m10s1(x)
      real :: x(10)
@@ -144,7 +144,7 @@ program m11
      real, allocatable :: x
    end subroutine
  end interface
-  !ERROR: Generic 'g2' may not have specific procedures 'm11s3' and 'm11s4' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g2' should not have specific procedures 'm11s3' and 'm11s4' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g2
    subroutine m11s3(x)
      real, pointer, intent(in) :: x
@@ -156,11 +156,11 @@ program m11
 end

 module m12
-  !ERROR: Generic 'g1' may not have specific procedures 's1' and 's2' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g1' should not have specific procedures 's1' and 's2' as their interfaces are not distinguishable by the incomplete rules in the standard
  generic :: g1 => s1, s2  ! rank-1 and assumed-rank
-  !ERROR: Generic 'g2' may not have specific procedures 's2' and 's3' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g2' should not have specific procedures 's2' and 's3' as their interfaces are not distinguishable by the incomplete rules in the standard
  generic :: g2 => s2, s3  ! scalar and assumed-rank
-  !ERROR: Generic 'g3' may not have specific procedures 's1' and 's4' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g3' should not have specific procedures 's1' and 's4' as their interfaces are not distinguishable by the incomplete rules in the standard
  generic :: g3 => s1, s4  ! different shape, same rank
 contains
  subroutine s1(x)
@@ -209,7 +209,7 @@ module m14
    module procedure f1
    module procedure f2
  end interface
-  !ERROR: Generic 'OPERATOR(+)' may not have specific procedures 'f1' and 'f3' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'OPERATOR(+)' should not have specific procedures 'f1' and 'f3' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface operator(+)
    module procedure f1
    module procedure f3
@@ -218,7 +218,7 @@ module m14
    module procedure f1
    module procedure f2
  end interface
-  !ERROR: Generic 'OPERATOR(.bar.)' may not have specific procedures 'f1' and 'f3' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'OPERATOR(.bar.)' should not have specific procedures 'f1' and 'f3' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface operator(.bar.)
    module procedure f1
    module procedure f3
@@ -260,12 +260,12 @@ module m15
    procedure s1
    procedure s2
  end interface
-  !ERROR: Generic 'g2' may not have specific procedures 's1' and 's3' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g2' should not have specific procedures 's1' and 's3' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g2
    procedure s1
    procedure s3
  end interface
-  !ERROR: Generic 'g3' may not have specific procedures 's4' and 's5' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g3' should not have specific procedures 's4' and 's5' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g3
    procedure s4
    procedure s5
@@ -285,17 +285,17 @@ module m15
    procedure s8
    procedure s9
  end interface
-  !ERROR: Generic 'g7' may not have specific procedures 's6' and 's7' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g7' should not have specific procedures 's6' and 's7' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g7
    procedure s6
    procedure s7
  end interface
-  !ERROR: Generic 'g8' may not have specific procedures 's6' and 's8' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g8' should not have specific procedures 's6' and 's8' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g8
    procedure s6
    procedure s8
  end interface
-  !ERROR: Generic 'g9' may not have specific procedures 's7' and 's8' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g9' should not have specific procedures 's7' and 's8' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g9
    procedure s7
    procedure s8
@@ -339,7 +339,7 @@ module m16
    procedure, nopass :: s2
    procedure, nopass :: s3
    generic :: g1 => s1, s2
-    !ERROR: Generic 'g2' may not have specific procedures 's1' and 's3' as their interfaces are not distinguishable
+    !PORTABILITY: Generic 'g2' should not have specific procedures 's1' and 's3' as their interfaces are not distinguishable by the incomplete rules in the standard
    generic :: g2 => s1, s3
  end type
 contains
@@ -368,7 +368,7 @@ module m17
    procedure s1
    procedure s2
  end interface
-  !ERROR: Generic 'g2' may not have specific procedures 's3' and 's4' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g2' should not have specific procedures 's3' and 's4' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g2
    procedure s3
    procedure s4
@@ -377,17 +377,17 @@ module m17
    procedure s1
    procedure s4
  end interface
-  !ERROR: Generic 'g4' may not have specific procedures 's2' and 's3' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g4' should not have specific procedures 's2' and 's3' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g4
    procedure s2
    procedure s3
  end interface
-  !ERROR: Generic 'g5' may not have specific procedures 's2' and 's5' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g5' should not have specific procedures 's2' and 's5' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g5
    procedure s2
    procedure s5
  end interface
-  !ERROR: Generic 'g6' may not have specific procedures 's2' and 's6' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'g6' should not have specific procedures 's2' and 's6' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface g6
    procedure s2
    procedure s6
@@ -439,7 +439,7 @@ module m19
    module procedure f1
    module procedure f2
  end interface
-  !ERROR: Generic 'OPERATOR(.bar.)' may not have specific procedures 'f2' and 'f3' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'OPERATOR(.bar.)' should not have specific procedures 'f2' and 'f3' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface operator(.bar.)
    module procedure f2
    module procedure f3
@@ -504,3 +504,21 @@ module m21
    class(*), allocatable :: x
  end subroutine
 end module
+
+! Example reduced from pFUnit
+module m22
+  !PORTABILITY: Generic 'generic' should not have specific procedures 'sub1' and 'sub2' as their interfaces are not distinguishable by the incomplete rules in the standard
+  interface generic
+    procedure sub1, sub2
+  end interface
+ contains
+  subroutine sub1(b, c)
+    class(*) b
+    integer, optional :: c
+  end
+  subroutine sub2(a, b, c)
+    real a
+    class(*) b
+    integer, optional :: c
+  end
+end
--- a/flang/test/Semantics/resolve54.f90
+++ b/flang/test/Semantics/resolve54.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic -Werror
 ! Tests based on examples in C.10.6

 ! C.10.6(10)
@@ -55,7 +55,7 @@ end
 ! C.10.6(17)
 ! BAD4(1.0,2,Y=3.0,Z=4) could apply to either procedure
 module m4
-  !ERROR: Generic 'bad4' may not have specific procedures 's4a' and 's4b' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'bad4' should not have specific procedures 's4a' and 's4b' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface BAD4
    subroutine S4A(W, X, Y, Z)
      real :: W, Y
@@ -68,7 +68,7 @@ module m4
  end interface
 end
 module m4b
-  !ERROR: Generic 'bad4' may not have specific procedures 's4b' and 's4a' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'bad4' should not have specific procedures 's4b' and 's4a' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface BAD4
    subroutine S4B(X, W, Z, Y)
      real :: X, Y
@@ -109,7 +109,7 @@ end
 ! type(BOSC) :: A_BOSC
 ! BAD6(A_PEAR,A_BOSC)  ! could be s6a or s6b
 module m6
-  !ERROR: Generic 'bad6' may not have specific procedures 's6a' and 's6b' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'bad6' should not have specific procedures 's6a' and 's6b' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface BAD6
    subroutine S6A(X, Y)
      use FRUITS
@@ -123,7 +123,7 @@ module m6
  end interface
 end
 module m6b
-  !ERROR: Generic 'bad6' may not have specific procedures 's6b' and 's6a' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'bad6' should not have specific procedures 's6b' and 's6a' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface BAD6
    subroutine S6B(X, Y)
      use FRUITS
@@ -170,7 +170,7 @@ end
 ! C.10.6(25)
 ! Invalid generic (according to the rules), despite the fact that it is unambiguous
 module m8
-  !ERROR: Generic 'bad8' may not have specific procedures 's8a' and 's8b' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'bad8' should not have specific procedures 's8a' and 's8b' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface BAD8
    subroutine S8A(X, Y, Z)
      real, optional :: X
--- a/flang/test/Semantics/resolve63.f90
+++ b/flang/test/Semantics/resolve63.f90
@@ -340,7 +340,7 @@ module m8
    call generic(null(), ip) ! ok
    call generic(null(mold=ip), null()) ! ok
    call generic(null(), null(mold=ip)) ! ok
-    !ERROR: One or more actual arguments to the generic procedure 'generic' matched multiple specific procedures, perhaps due to use of NULL() without MOLD= or an actual procedure with an implicit interface
+    !ERROR: The actual arguments to the generic procedure 'generic' matched multiple specific procedures, perhaps due to use of NULL() without MOLD= or an actual procedure with an implicit interface
    call generic(null(), null())
  end subroutine
 end
@@ -358,7 +358,7 @@ module m9
  end subroutine
  subroutine test
    external underspecified
-    !ERROR: One or more actual arguments to the generic procedure 'generic' matched multiple specific procedures, perhaps due to use of NULL() without MOLD= or an actual procedure with an implicit interface
+    !ERROR: The actual arguments to the generic procedure 'generic' matched multiple specific procedures, perhaps due to use of NULL() without MOLD= or an actual procedure with an implicit interface
    call generic(underspecified)
  end subroutine
 end module
--- a/flang/test/Semantics/resolve65.f90
+++ b/flang/test/Semantics/resolve65.f90
@@ -1,13 +1,13 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic
 ! Test restrictions on what subprograms can be used for defined assignment.

 module m1
  implicit none
  type :: t
  contains
-    !ERROR: Generic 'assignment(=)' may not have specific procedures 't%assign_t4' and 't%assign_t5' as their interfaces are not distinguishable
-    !ERROR: Generic 'assignment(=)' may not have specific procedures 't%assign_t4' and 't%assign_t6' as their interfaces are not distinguishable
-    !ERROR: Generic 'assignment(=)' may not have specific procedures 't%assign_t5' and 't%assign_t6' as their interfaces are not distinguishable
+    !PORTABILITY: Generic 'assignment(=)' should not have specific procedures 't%assign_t4' and 't%assign_t5' as their interfaces are not distinguishable by the incomplete rules in the standard
+    !PORTABILITY: Generic 'assignment(=)' should not have specific procedures 't%assign_t4' and 't%assign_t6' as their interfaces are not distinguishable by the incomplete rules in the standard
+    !PORTABILITY: Generic 'assignment(=)' should not have specific procedures 't%assign_t5' and 't%assign_t6' as their interfaces are not distinguishable by the incomplete rules in the standard
    !ERROR: Defined assignment procedure 'binding' must be a subroutine
    generic :: assignment(=) => binding
    procedure :: binding => assign_t1
@@ -63,7 +63,7 @@ end
 module m2
  type :: t
  end type
-  !ERROR: Generic 'assignment(=)' may not have specific procedures 's3' and 's4' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'assignment(=)' should not have specific procedures 's3' and 's4' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface assignment(=)
    !ERROR: In defined assignment subroutine 's1', dummy argument 'y' may not be OPTIONAL
    subroutine s1(x, y)
--- a/flang/test/Semantics/resolve96.f90
+++ b/flang/test/Semantics/resolve96.f90
@@ -1,4 +1,4 @@
-! RUN: %python %S/test_errors.py %s %flang_fc1
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic -Werror

 ! Check distinguishability for specific procedures of defined operators and
 ! assignment. These are different from names because there a normal generic
@@ -18,7 +18,7 @@ module m1
  end type
  type :: t2
  end type
-  !ERROR: Generic 'OPERATOR(.foo.)' may not have specific procedures 's2' and 't1%p' as their interfaces are not distinguishable
+  !PORTABILITY: Generic 'OPERATOR(.foo.)' should not have specific procedures 's2' and 't1%p' as their interfaces are not distinguishable by the incomplete rules in the standard
  interface operator(.foo.)
    procedure :: s2
  end interface
@@ -39,7 +39,7 @@ module m2
    integer :: n
  contains
    procedure, pass(x1) :: p1 => s1
-    !ERROR: Generic 'assignment(=)' may not have specific procedures 't1%p1' and 't2%p2' as their interfaces are not distinguishable
+    !PORTABILITY: Generic 'assignment(=)' should not have specific procedures 't1%p1' and 't2%p2' as their interfaces are not distinguishable by the incomplete rules in the standard
    generic :: assignment(=) => p1
  end type
  type :: t2