[flang-commits] [flang] [Flang][OpenMP] Add some semantic checks for Linear clause (PR #111354)

[Krzysztof Parzyszek via flang-commits]

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@@ -3040,16 +3064,101 @@ void OmpStructureChecker::Enter(const parser::OmpClause::If &x) {
 void OmpStructureChecker::Enter(const parser::OmpClause::Linear &x) {
   CheckAllowedClause(llvm::omp::Clause::OMPC_linear);
 
+  parser::CharBlock source{GetContext().clauseSource};
   // 2.7 Loop Construct Restriction
   if ((llvm::omp::allDoSet | llvm::omp::allSimdSet)
           .test(GetContext().directive)) {
     if (std::holds_alternative<parser::OmpLinearClause::WithModifier>(x.v.u)) {
-      context_.Say(GetContext().clauseSource,
+      context_.Say(source,
           "A modifier may not be specified in a LINEAR clause "
           "on the %s directive"_err_en_US,
           ContextDirectiveAsFortran());
+      return;
+    }
+  }
+
+  // OpenMP 5.2: Ordered clause restriction
+  if (const auto *clause{
+          FindClause(GetContext(), llvm::omp::Clause::OMPC_ordered)}) {
+    const auto &orderedClause{std::get<parser::OmpClause::Ordered>(clause->u)};
+    if (orderedClause.v) {
+      return;
     }
   }
+
+  auto checkForValidLinearClause = [&](const parser::Name &name, bool is_ref) {
+    parser::CharBlock source{GetContext().clauseSource};
+    std::string listItemName{name.ToString()};
+    if (!is_ref && !name.symbol->GetType()->IsNumeric(TypeCategory::Integer)) {
+      context_.Say(source,
+          "The list item `%s` specified with other than linear-modifier `REF`"
+          " must be of type INTEGER"_err_en_US,
+          listItemName);
+    }
+    if (GetContext().directive == llvm::omp::Directive::OMPD_declare_simd &&
+        !IsDummy(*name.symbol)) {
+      context_.Say(source,
+          "The list item `%s` must be a dummy argument"_err_en_US,
+          listItemName);
+    }
+    if (IsPointer(*name.symbol) ||
+        name.symbol->test(Symbol::Flag::CrayPointer)) {
+      context_.Say(source,
+          "The list item `%s` in a LINEAR clause must not be Cray Pointer "
+          "or a variable with POINTER attribute"_err_en_US,
+          listItemName);
+    }
+    if (FindCommonBlockContaining(*name.symbol)) {
+      context_.Say(source,
+          "'%s' is a common block name and must not appear in an "
+          "LINEAR clause"_err_en_US,
+          listItemName);
+    }
+  };
+
+  // OpenMP 5.2: Linear clause Restrictions
+  common::visit(
+      common::visitors{
+          [&](const parser::OmpLinearClause::WithoutModifier &withoutModifier) {
+            for (const auto &name : withoutModifier.names) {
+              if (name.symbol) {
+                checkForValidLinearClause(name, false);
+              }
+            }
+          },
+          [&](const parser::OmpLinearClause::WithModifier &withModifier) {
+            for (const auto &name : withModifier.names) {
+              if (name.symbol) {
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kparzysz wrote:

You can extract this into a lamda to reduce indentation.

https://github.com/llvm/llvm-project/pull/111354