[flang-commits] [flang] [flang][semantics] fix IsConstantExpr for intrinsic with optional argument (PR #161915)

Andre Kuhlenschmidt via flang-commits flang-commits at lists.llvm.org
Fri Oct 3 22:03:27 PDT 2025


https://github.com/akuhlens updated https://github.com/llvm/llvm-project/pull/161915

>From 3e11d688a7bb19ddb1a893e5b016e368acc82092 Mon Sep 17 00:00:00 2001
From: Andre Kuhlenschmidt <akuhlenschmi at nvidia.com>
Date: Fri, 3 Oct 2025 14:53:58 -0700
Subject: [PATCH 1/7] initial commit

---
 flang/include/flang/Parser/message.h |  2 +-
 flang/lib/Parser/message.cpp         | 24 ++++++++++++++++++++----
 flang/test/Semantics/associated.f90  |  2 --
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/flang/include/flang/Parser/message.h b/flang/include/flang/Parser/message.h
index 224263e4be860..7c639eff1eeef 100644
--- a/flang/include/flang/Parser/message.h
+++ b/flang/include/flang/Parser/message.h
@@ -307,9 +307,9 @@ class Message : public common::ReferenceCounted<Message> {
   bool Merge(const Message &);
   bool operator==(const Message &that) const;
   bool operator!=(const Message &that) const { return !(*this == that); }
+  bool AtSameLocation(const Message &) const;
 
 private:
-  bool AtSameLocation(const Message &) const;
   std::variant<ProvenanceRange, CharBlock> location_;
   std::variant<MessageFixedText, MessageFormattedText, MessageExpectedText>
       text_;
diff --git a/flang/lib/Parser/message.cpp b/flang/lib/Parser/message.cpp
index 2c4f930c0b088..0e06711c5b71b 100644
--- a/flang/lib/Parser/message.cpp
+++ b/flang/lib/Parser/message.cpp
@@ -477,15 +477,31 @@ void Messages::Emit(llvm::raw_ostream &o, const AllCookedSources &allCooked,
   }
   std::stable_sort(sorted.begin(), sorted.end(),
       [](const Message *x, const Message *y) { return x->SortBefore(*y); });
-  const Message *lastMsg{nullptr};
+  std::vector<const Message *> msgsWithLastLocation;
   std::size_t errorsEmitted{0};
   for (const Message *msg : sorted) {
-    if (lastMsg && *msg == *lastMsg) {
-      // Don't emit two identical messages for the same location
+    bool shouldSkipMsg = false;
+    // Don't emit two identical messages for the same location
+    // At the same location messages are sorted by the order they were
+    // added to the list, which is a decent proxy for the causality
+    // of the messages.
+    if (!msgsWithLastLocation.empty()) {
+      if (msgsWithLastLocation[0]->AtSameLocation(*msg)) {
+        for (const Message *msgAtThisLocation : msgsWithLastLocation) {
+          if (*msg == *msgAtThisLocation) {
+            shouldSkipMsg = true; // continue loop over sorted messages
+            break;
+          }
+        }
+      } else {
+        msgsWithLastLocation.clear();
+      }
+    }
+    if (shouldSkipMsg) {
       continue;
     }
+    msgsWithLastLocation.push_back(msg);
     msg->Emit(o, allCooked, echoSourceLines, hintFlagPtr);
-    lastMsg = msg;
     if (warningsAreErrors || msg->IsFatal()) {
       ++errorsEmitted;
     }
diff --git a/flang/test/Semantics/associated.f90 b/flang/test/Semantics/associated.f90
index 7cb6c240db226..731f2d828995f 100644
--- a/flang/test/Semantics/associated.f90
+++ b/flang/test/Semantics/associated.f90
@@ -253,8 +253,6 @@ subroutine test(assumedRank)
     lvar = associated(intPointerVar1, targetIntCoarray[1])
     !ERROR: 'neverdeclared' is not a procedure
     !ERROR: Could not characterize intrinsic function actual argument 'badpointer'
-    !ERROR: 'neverdeclared' is not a procedure
-    !ERROR: Could not characterize intrinsic function actual argument 'badpointer'
     lvar = associated(badPointer)
   end subroutine test
 end subroutine assoc

>From 22e8f069f67cc740d36d6da52441a54d9093cbfe Mon Sep 17 00:00:00 2001
From: Andre Kuhlenschmidt <akuhlenschmi at nvidia.com>
Date: Fri, 3 Oct 2025 15:29:05 -0700
Subject: [PATCH 2/7] don't used brace initialization

---
 flang/lib/Parser/message.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/flang/lib/Parser/message.cpp b/flang/lib/Parser/message.cpp
index 0e06711c5b71b..006d3be74b6fe 100644
--- a/flang/lib/Parser/message.cpp
+++ b/flang/lib/Parser/message.cpp
@@ -480,7 +480,7 @@ void Messages::Emit(llvm::raw_ostream &o, const AllCookedSources &allCooked,
   std::vector<const Message *> msgsWithLastLocation;
   std::size_t errorsEmitted{0};
   for (const Message *msg : sorted) {
-    bool shouldSkipMsg = false;
+    bool shouldSkipMsg{false};
     // Don't emit two identical messages for the same location
     // At the same location messages are sorted by the order they were
     // added to the list, which is a decent proxy for the causality

>From 7bb937ed5ad529d292d1b8a3a32de56f8255d18d Mon Sep 17 00:00:00 2001
From: Andre Kuhlenschmidt <akuhlenschmi at nvidia.com>
Date: Fri, 3 Oct 2025 15:44:46 -0700
Subject: [PATCH 3/7] clean up comment

---
 flang/lib/Parser/message.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/flang/lib/Parser/message.cpp b/flang/lib/Parser/message.cpp
index 006d3be74b6fe..cfcd08b0861ef 100644
--- a/flang/lib/Parser/message.cpp
+++ b/flang/lib/Parser/message.cpp
@@ -481,10 +481,10 @@ void Messages::Emit(llvm::raw_ostream &o, const AllCookedSources &allCooked,
   std::size_t errorsEmitted{0};
   for (const Message *msg : sorted) {
     bool shouldSkipMsg{false};
-    // Don't emit two identical messages for the same location
-    // At the same location messages are sorted by the order they were
-    // added to the list, which is a decent proxy for the causality
-    // of the messages.
+    // Don't emit two identical messages for the same location.
+    // At the same location, messages are sorted by the order they were
+    // added to the Messages buffer, which is a decent proxy for the
+    // causality of the messages.
     if (!msgsWithLastLocation.empty()) {
       if (msgsWithLastLocation[0]->AtSameLocation(*msg)) {
         for (const Message *msgAtThisLocation : msgsWithLastLocation) {

>From 904ed439d37a9dbb0606b80b39990b86b7556724 Mon Sep 17 00:00:00 2001
From: Andre Kuhlenschmidt <akuhlenschmi at nvidia.com>
Date: Fri, 3 Oct 2025 09:32:18 -0700
Subject: [PATCH 4/7] initial commit

---
 flang/lib/Evaluate/check-expression.cpp | 17 +++++++++++------
 flang/test/Semantics/intrinsics03.f90   |  5 ++++-
 flang/test/Semantics/intrinsics04.f90   |  5 ++++-
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/flang/lib/Evaluate/check-expression.cpp b/flang/lib/Evaluate/check-expression.cpp
index 8931cbe485ac2..012b44e7d3747 100644
--- a/flang/lib/Evaluate/check-expression.cpp
+++ b/flang/lib/Evaluate/check-expression.cpp
@@ -135,16 +135,21 @@ bool IsConstantExprHelper<INVARIANT>::operator()(
     } else if (proc.IsPure()) {
       std::size_t j{0};
       for (const auto &arg : call.arguments()) {
-        if (const auto *dataDummy{j < proc.dummyArguments.size()
-                    ? std::get_if<characteristics::DummyDataObject>(
-                          &proc.dummyArguments[j].u)
-                    : nullptr};
-            dataDummy &&
+        const auto *dataDummy{j < proc.dummyArguments.size()
+                ? std::get_if<characteristics::DummyDataObject>(
+                      &proc.dummyArguments[j].u)
+                : nullptr};
+        if (dataDummy &&
             dataDummy->attrs.test(
                 characteristics::DummyDataObject::Attr::OnlyIntrinsicInquiry)) {
           // The value of the argument doesn't matter
         } else if (!arg) {
-          return false;
+          // Missing optional arguments are constant
+          if (!(dataDummy &&
+                  dataDummy->attrs.test(
+                      characteristics::DummyDataObject::Attr::Optional))) {
+            return false;
+          }
         } else if (const auto *expr{arg->UnwrapExpr()};
             !expr || !(*this)(*expr)) {
           return false;
diff --git a/flang/test/Semantics/intrinsics03.f90 b/flang/test/Semantics/intrinsics03.f90
index a5b13b655cf41..2b07c5ee98eaf 100644
--- a/flang/test/Semantics/intrinsics03.f90
+++ b/flang/test/Semantics/intrinsics03.f90
@@ -129,6 +129,9 @@ subroutine ichar_tests()
   !Without -Wportability, the warning isn't emitted and the parameter is constant.
   integer, parameter :: a2 = ichar('B ')
   !ERROR: Character in intrinsic function ichar must have length one
-  !ERROR: Must be a constant value
+  !ERROR: Value of named constant 'a3' (ichar("")) cannot be computed as a constant value
+  !ERROR: Character in intrinsic function ichar must have length one
+  !ERROR: Value of named constant 'a3' (ichar("")) cannot be computed as a constant value
+  !ERROR: Character in intrinsic function ichar must have length one
   integer, parameter :: a3 = ichar('')
 end subroutine
diff --git a/flang/test/Semantics/intrinsics04.f90 b/flang/test/Semantics/intrinsics04.f90
index abb8fe321a572..8b6b29fed2128 100644
--- a/flang/test/Semantics/intrinsics04.f90
+++ b/flang/test/Semantics/intrinsics04.f90
@@ -29,6 +29,9 @@ subroutine ichar_tests()
   !WARNING: Character in intrinsic function ichar should have length one [-Wportability]
   integer, parameter :: a2 = ichar('B ')
   !ERROR: Character in intrinsic function ichar must have length one
-  !ERROR: Must be a constant value
+  !ERROR: Value of named constant 'a3' (ichar("")) cannot be computed as a constant value
+  !ERROR: Character in intrinsic function ichar must have length one
+  !ERROR: Value of named constant 'a3' (ichar("")) cannot be computed as a constant value
+  !ERROR: Character in intrinsic function ichar must have length one
   integer, parameter :: a3 = ichar('')
 end subroutine

>From 8c3b43fb3d3346504dddc009c80105df6df14e8a Mon Sep 17 00:00:00 2001
From: Andre Kuhlenschmidt <akuhlenschmi at nvidia.com>
Date: Fri, 3 Oct 2025 15:37:09 -0700
Subject: [PATCH 5/7] address feedback

---
 flang/lib/Evaluate/check-expression.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/flang/lib/Evaluate/check-expression.cpp b/flang/lib/Evaluate/check-expression.cpp
index 012b44e7d3747..647eebaaa070b 100644
--- a/flang/lib/Evaluate/check-expression.cpp
+++ b/flang/lib/Evaluate/check-expression.cpp
@@ -144,10 +144,11 @@ bool IsConstantExprHelper<INVARIANT>::operator()(
                 characteristics::DummyDataObject::Attr::OnlyIntrinsicInquiry)) {
           // The value of the argument doesn't matter
         } else if (!arg) {
-          // Missing optional arguments are constant
-          if (!(dataDummy &&
-                  dataDummy->attrs.test(
-                      characteristics::DummyDataObject::Attr::Optional))) {
+          if (dataDummy &&
+              dataDummy->attrs.test(
+                  characteristics::DummyDataObject::Attr::Optional)) {
+            // Missing optional arguments are okay.
+          } else {
             return false;
           }
         } else if (const auto *expr{arg->UnwrapExpr()};

>From d9811423ce68826043e4792c09e525fb5e616d8c Mon Sep 17 00:00:00 2001
From: Andre Kuhlenschmidt <akuhlenschmi at nvidia.com>
Date: Fri, 3 Oct 2025 16:06:20 -0700
Subject: [PATCH 6/7] add test

---
 flang/test/Semantics/type-parameter-constant.f90 | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 flang/test/Semantics/type-parameter-constant.f90

diff --git a/flang/test/Semantics/type-parameter-constant.f90 b/flang/test/Semantics/type-parameter-constant.f90
new file mode 100644
index 0000000000000..376bffd0233ff
--- /dev/null
+++ b/flang/test/Semantics/type-parameter-constant.f90
@@ -0,0 +1,15 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+type A (p, r)
+  integer, kind :: p, r
+  !ERROR: KIND parameter expression (int(selected_real_kind(six,twenty_three),kind=8)) of intrinsic type REAL did not resolve to a constant value
+  real (selected_real_kind(p, r)) :: data
+end type
+   integer :: six = 6, twenty_three = 23
+   type(a(6,23)) :: a1
+   !ERROR: Value of KIND type parameter 'p' must be constant
+   !ERROR: Value of KIND type parameter 'r' must be constant
+   !WARNING: specification expression refers to local object 'six' (initialized and saved) [-Wsaved-local-in-spec-expr]
+   !WARNING: specification expression refers to local object 'twenty_three' (initialized and saved) [-Wsaved-local-in-spec-expr]
+   type(a(six, twenty_three)) :: a2 
+   print *, a1%data%kind
+end
\ No newline at end of file

>From b395191a517a61456fad7271ee58353021a9f6b6 Mon Sep 17 00:00:00 2001
From: Andre Kuhlenschmidt <akuhlenschmi at nvidia.com>
Date: Fri, 3 Oct 2025 16:17:58 -0700
Subject: [PATCH 7/7] fix duplicate messages in results

---
 flang/test/Semantics/intrinsics03.f90 | 3 ---
 flang/test/Semantics/intrinsics04.f90 | 3 ---
 2 files changed, 6 deletions(-)

diff --git a/flang/test/Semantics/intrinsics03.f90 b/flang/test/Semantics/intrinsics03.f90
index 2b07c5ee98eaf..1a4269868a3d4 100644
--- a/flang/test/Semantics/intrinsics03.f90
+++ b/flang/test/Semantics/intrinsics03.f90
@@ -130,8 +130,5 @@ subroutine ichar_tests()
   integer, parameter :: a2 = ichar('B ')
   !ERROR: Character in intrinsic function ichar must have length one
   !ERROR: Value of named constant 'a3' (ichar("")) cannot be computed as a constant value
-  !ERROR: Character in intrinsic function ichar must have length one
-  !ERROR: Value of named constant 'a3' (ichar("")) cannot be computed as a constant value
-  !ERROR: Character in intrinsic function ichar must have length one
   integer, parameter :: a3 = ichar('')
 end subroutine
diff --git a/flang/test/Semantics/intrinsics04.f90 b/flang/test/Semantics/intrinsics04.f90
index 8b6b29fed2128..e733067237d17 100644
--- a/flang/test/Semantics/intrinsics04.f90
+++ b/flang/test/Semantics/intrinsics04.f90
@@ -30,8 +30,5 @@ subroutine ichar_tests()
   integer, parameter :: a2 = ichar('B ')
   !ERROR: Character in intrinsic function ichar must have length one
   !ERROR: Value of named constant 'a3' (ichar("")) cannot be computed as a constant value
-  !ERROR: Character in intrinsic function ichar must have length one
-  !ERROR: Value of named constant 'a3' (ichar("")) cannot be computed as a constant value
-  !ERROR: Character in intrinsic function ichar must have length one
   integer, parameter :: a3 = ichar('')
 end subroutine



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