[flang-commits] [flang] [flang] USE-associated explicit INTRINSIC names (PR #76199)

[Peter Klausler via flang-commits]

https://github.com/klausler updated https://github.com/llvm/llvm-project/pull/76199

>From e1c7ed34146692f6cc38477f4e9247eee22bac88 Mon Sep 17 00:00:00 2001
From: Peter Klausler <pklausler at nvidia.com>
Date: Thu, 21 Dec 2023 16:45:37 -0800
Subject: [PATCH] [flang] USE-associated explicit INTRINSIC names

The compiler doesn't USE-associate the names of intrinsic procedures
from modules (in the absence of ONLY:), so that the associating
scope doesn't get populated with names of intrinsics that were used
only in declarations (e.g., SELECTED_REAL_KIND).  A recent bug report
(below) shows that we should modify that policy in the case of names
that appear in explicit INTRINSIC attribute statements.  The behaviors
of other Fortran compilers are not consistent and the requirements of the
standard are not clear; this fix follows the precedent set by gfortran
and nvfortran.

Fixes https://github.com/llvm/llvm-project/issues/72084.
---
 flang/docs/Extensions.md              |  4 ++++
 flang/lib/Semantics/resolve-names.cpp | 10 +++++-----
 flang/test/Semantics/intrinsics02.f90 | 16 ++++++++++++++++
 3 files changed, 25 insertions(+), 5 deletions(-)
 create mode 100644 flang/test/Semantics/intrinsics02.f90

diff --git a/flang/docs/Extensions.md b/flang/docs/Extensions.md
index 03d4310466485c..6c6588025a392d 100644
--- a/flang/docs/Extensions.md
+++ b/flang/docs/Extensions.md
@@ -641,6 +641,10 @@ module m
 end
 ```
 
+* When an intrinsic procedure appears in the specification part of a module
+  only in function references, but not an explicit `INTRINSIC` statement,
+  its name is not brought into other scopes by a `USE` statement.
+
 ## De Facto Standard Features
 
 * `EXTENDS_TYPE_OF()` returns `.TRUE.` if both of its arguments have the
diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index e1cd34ddf65b6b..73f240abc95b7b 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -2904,7 +2904,7 @@ void ModuleVisitor::Post(const parser::UseStmt &x) {
     }
     for (const auto &[name, symbol] : *useModuleScope_) {
       if (symbol->attrs().test(Attr::PUBLIC) && !IsUseRenamed(symbol->name()) &&
-          (!symbol->attrs().test(Attr::INTRINSIC) ||
+          (!symbol->implicitAttrs().test(Attr::INTRINSIC) ||
               symbol->has<UseDetails>()) &&
           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
         SourceName location{x.moduleName.source};
@@ -6244,8 +6244,8 @@ bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
     // recreated for it later on demand, but capturing its result type here
     // will make GetType() return a correct result without having to
     // probe the intrinsics table again.
-    Symbol &symbol{
-        MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
+    Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
+    SetImplicitAttr(symbol, Attr::INTRINSIC);
     CHECK(interface->functionResult.has_value());
     evaluate::DynamicType dyType{
         DEREF(interface->functionResult->GetTypeAndShape()).type()};
@@ -7708,8 +7708,8 @@ void ResolveNamesVisitor::HandleProcedureName(
   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
   if (!symbol) {
     if (IsIntrinsic(name.source, flag)) {
-      symbol =
-          &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
+      symbol = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
+      SetImplicitAttr(*symbol, Attr::INTRINSIC);
     } else if (const auto ppcBuiltinScope =
                    currScope().context().GetPPCBuiltinsScope()) {
       // Check if it is a builtin from the predefined module
diff --git a/flang/test/Semantics/intrinsics02.f90 b/flang/test/Semantics/intrinsics02.f90
new file mode 100644
index 00000000000000..1b8dc4f34ba69c
--- /dev/null
+++ b/flang/test/Semantics/intrinsics02.f90
@@ -0,0 +1,16 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+module explicit
+  intrinsic cos
+end
+subroutine testExplicit
+  use explicit
+  !ERROR: 'cos' is use-associated from module 'explicit' and cannot be re-declared
+  real :: cos = 2.
+end
+module implicit
+  real :: one = cos(0.)
+end
+subroutine testImplicit
+  use implicit
+  real :: cos = 2.
+end