[flang-commits] [flang] 8d0fabe - [flang] Improve intrinsic error messages when multiple signatures exist (#172099)

[via flang-commits]

Author: TMJ
Date: 2025-12-16T10:02:14-05:00
New Revision: 8d0fabe8fe8068b1cce1995366f1344502e36520

URL: https://github.com/llvm/llvm-project/commit/8d0fabe8fe8068b1cce1995366f1344502e36520
DIFF: https://github.com/llvm/llvm-project/commit/8d0fabe8fe8068b1cce1995366f1344502e36520.diff

LOG: [flang] Improve intrinsic error messages when multiple signatures exist (#172099)

When an intrinsic has multiple table entries (e.g., BESSEL_JN has both
elemental and transformational forms), the error message selection logic
now prefers specific argument errors over generic "too many actual
arguments" messages.

For example, given:

    real, dimension(10) :: xarray
    integer :: n1, n2
    print *, bessel_jn(n1, n2, xarray)

The transformational form of BESSEL_JN(n1, n2, x) requires x to be
scalar. Previously, flang reported "too many actual arguments" from the
elemental form (which only accepts 2 args), even though the
transformational form matched the argument count but failed on rank.

Now flang correctly reports "x= argument has unacceptable rank 1", which
better guides the user to the actual problem.

The fix extends the error buffer selection heuristic in Probe() to
prefer later table entries when earlier entries fail with argument count
mismatches.

Added: 
    flang/test/Semantics/bessel_jn.f90

Modified: 
    flang/lib/Evaluate/intrinsics.cpp
    flang/test/Semantics/num_images01.f90
    flang/test/Semantics/num_images02.f90

Removed: 
    


################################################################################
diff  --git a/flang/lib/Evaluate/intrinsics.cpp b/flang/lib/Evaluate/intrinsics.cpp
index da39f199cab43..72ac9e2f68758 100644
--- a/flang/lib/Evaluate/intrinsics.cpp
+++ b/flang/lib/Evaluate/intrinsics.cpp
@@ -3597,8 +3597,13 @@ std::optional<SpecificCall> IntrinsicProcTable::Implementation::Probe(
           // presence of DIM=, use messages from a later entry if
           // the messages from an earlier entry complain about the
           // DIM= argument and it wasn't specified with a keyword.
+          // Also prefer later messages when earlier ones are about
+          // argument count mismatches, as a later entry that accepts
+          // the right number of arguments will give more specific errors.
+          bool preferLaterError{false};
           for (const auto &m : buffer.messages()) {
-            if (m.ToString().find("'dim='") != std::string::npos) {
+            std::string text{m.ToString()};
+            if (text.find("'dim='") != std::string::npos) {
               bool hadDimKeyword{false};
               for (const auto &a : arguments) {
                 if (a) {
@@ -3609,11 +3614,20 @@ std::optional<SpecificCall> IntrinsicProcTable::Implementation::Probe(
                 }
               }
               if (!hadDimKeyword) {
-                buffer = std::move(localBuffer);
+                preferLaterError = true;
               }
               break;
+            } else if (text.find("too many actual arguments") !=
+                std::string::npos) {
+              // Prefer messages from an entry that matched the argument
+              // count, as those will be more specific about what's wrong
+              preferLaterError = true;
+              break;
             }
           }
+          if (preferLaterError) {
+            buffer = std::move(localBuffer);
+          }
           localBuffer.clear();
         }
         return std::nullopt;

diff  --git a/flang/test/Semantics/bessel_jn.f90 b/flang/test/Semantics/bessel_jn.f90
new file mode 100644
index 0000000000000..e94a6db44e09c
--- /dev/null
+++ b/flang/test/Semantics/bessel_jn.f90
@@ -0,0 +1,25 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+! Test semantic checking for BESSEL_JN and BESSEL_YN intrinsics
+
+program test_bessel
+  real :: x, result_scalar
+  real :: xarray(10), result_array(10)
+  integer :: n, n1, n2
+
+  ! Valid elemental forms
+  result_scalar = bessel_jn(n, x)
+  result_scalar = bessel_yn(n, x)
+  result_array = bessel_jn(n, xarray)
+  result_array = bessel_yn(n, xarray)
+
+  ! Valid transformational forms (x must be scalar)
+  result_array(n1:n2) = bessel_jn(n1, n2, x)
+  result_array(n1:n2) = bessel_yn(n1, n2, x)
+
+  ! Invalid: transformational form with array x
+  !ERROR: 'x=' argument has unacceptable rank 1
+  result_array(n1:n2) = bessel_jn(n1, n2, xarray)
+
+  !ERROR: 'x=' argument has unacceptable rank 1
+  result_array(n1:n2) = bessel_yn(n1, n2, xarray)
+end program

diff  --git a/flang/test/Semantics/num_images01.f90 b/flang/test/Semantics/num_images01.f90
index 37f360b2c691e..29d54ee840760 100644
--- a/flang/test/Semantics/num_images01.f90
+++ b/flang/test/Semantics/num_images01.f90
@@ -15,8 +15,7 @@ subroutine test
   print *, num_images(team=my_team)
 
   ! incorrectly typed argument
-  ! the error is seen as too many arguments to the num_images() call with no arguments
-  !ERROR: too many actual arguments for intrinsic 'num_images'
+  !ERROR: Actual argument for 'team=' has bad type 'REAL(4)'
   print *, num_images(3.4)
 
   ! call with too many arguments

diff  --git a/flang/test/Semantics/num_images02.f90 b/flang/test/Semantics/num_images02.f90
index c59f65ff771ea..f417f483243c7 100644
--- a/flang/test/Semantics/num_images02.f90
+++ b/flang/test/Semantics/num_images02.f90
@@ -36,7 +36,7 @@ program num_images_with_team_type
   n = num_images(team=league)
 
   ! incorrectly typed argument
-  !ERROR: too many actual arguments for intrinsic 'num_images'
+  !ERROR: Actual argument for 'team=' has bad type 'REAL(4)'
   n = num_images(3.4)
 
   !ERROR: too many actual arguments for intrinsic 'num_images'