[flang][OpenMP] Analyze objects in OmpObjectList on clauses (#155424)

This is intended to diagnose errors such as incorrect uses of
assumed-size arrays, for example.

Fixes #151990

Author: kparzysz

flang/lib/Semantics/check-omp-structure.cpp

@@ -268,6 +268,43 @@ bool OmpStructureChecker::CheckAllowedClause(llvmOmpClause clause) {
   return CheckAllowed(clause);
 }
 
+void OmpStructureChecker::AnalyzeObject(
+    const parser::OmpObject &object, bool allowAssumedSizeArrays) {
+  if (std::holds_alternative<parser::Name>(object.u)) {
+    // Do not analyze common block names. The analyzer will flag an error
+    // on those.
+    return;
+  }
+  if (auto *symbol{GetObjectSymbol(object)}) {
+    // Eliminate certain kinds of symbols before running the analyzer to
+    // avoid confusing error messages. The analyzer assumes that the context
+    // of the object use is an expression, and some diagnostics are tailored
+    // to that.
+    if (symbol->has<DerivedTypeDetails>() || symbol->has<MiscDetails>()) {
+      // Type names, construct names, etc.
+      return;
+    }
+    if (auto *typeSpec{symbol->GetType()}) {
+      if (typeSpec->category() == DeclTypeSpec::Category::Character) {
+        // Don't pass character objects to the analyzer, it can emit somewhat
+        // cryptic errors (e.g. "'obj' is not an array"). Substrings are
+        // checked elsewhere in OmpStructureChecker.
+        return;
+      }
+    }
+  }
+  evaluate::ExpressionAnalyzer ea{context_};
+  auto restore{ea.AllowWholeAssumedSizeArray(allowAssumedSizeArrays)};
+  common::visit([&](auto &&s) { ea.Analyze(s); }, object.u);
+}
+
+void OmpStructureChecker::AnalyzeObjects(
+    const parser::OmpObjectList &objects, bool allowAssumedSizeArrays) {
+  for (const parser::OmpObject &object : objects.v) {
+    AnalyzeObject(object, allowAssumedSizeArrays);
+  }
+}
+
 bool OmpStructureChecker::IsCloselyNestedRegion(const OmpDirectiveSet &set) {
   // Definition of close nesting:
   //
@@ -2697,8 +2734,9 @@ void OmpStructureChecker::Leave(const parser::OmpClauseList &) {
 void OmpStructureChecker::Enter(const parser::OmpClause &x) {
   SetContextClause(x);
 
+  llvm::omp::Clause id{x.Id()};
   // The visitors for these clauses do their own checks.
-  switch (x.Id()) {
+  switch (id) {
   case llvm::omp::Clause::OMPC_copyprivate:
   case llvm::omp::Clause::OMPC_enter:
   case llvm::omp::Clause::OMPC_lastprivate:
@@ -2712,7 +2750,7 @@ void OmpStructureChecker::Enter(const parser::OmpClause &x) {
   // Named constants are OK to be used within 'shared' and 'firstprivate'
   // clauses.  The check for this happens a few lines below.
   bool SharedOrFirstprivate = false;
-  switch (x.Id()) {
+  switch (id) {
   case llvm::omp::Clause::OMPC_shared:
   case llvm::omp::Clause::OMPC_firstprivate:
     SharedOrFirstprivate = true;
@@ -2721,7 +2759,20 @@ void OmpStructureChecker::Enter(const parser::OmpClause &x) {
     break;
   }
 
+  auto allowsAssumedSizeArrays{[](llvm::omp::Clause c) {
+    // These clauses allow assumed-size-arrays as list items.
+    switch (c) {
+    case llvm::omp::Clause::OMPC_map:
+    case llvm::omp::Clause::OMPC_shared:
+    case llvm::omp::Clause::OMPC_use_device_addr:
+      return true;
+    default:
+      return false;
+    }
+  }};
+
   if (const parser::OmpObjectList *objList{GetOmpObjectList(x)}) {
+    AnalyzeObjects(*objList, allowsAssumedSizeArrays(id));
     SymbolSourceMap symbols;
     GetSymbolsInObjectList(*objList, symbols);
     for (const auto &[symbol, source] : symbols) {

flang/lib/Semantics/check-omp-structure.h

@@ -167,6 +167,10 @@ class OmpStructureChecker
   void CheckVariableListItem(const SymbolSourceMap &symbols);
   void CheckDirectiveSpelling(
       parser::CharBlock spelling, llvm::omp::Directive id);
+  void AnalyzeObject(
+      const parser::OmpObject &object, bool allowAssumedSizeArrays = false);
+  void AnalyzeObjects(const parser::OmpObjectList &objects,
+      bool allowAssumedSizeArrays = false);
   void CheckMultipleOccurrence(semantics::UnorderedSymbolSet &listVars,
       const std::list<parser::Name> &nameList, const parser::CharBlock &item,
       const std::string &clauseName);

flang/test/Lower/OpenMP/Todo/omp-do-simd-linear.f90

@@ -3,7 +3,7 @@
 ! RUN: %not_todo_cmd bbc -emit-fir -fopenmp -o - %s 2>&1 | FileCheck %s
 ! RUN: %not_todo_cmd %flang_fc1 -emit-fir -fopenmp -o - %s 2>&1 | FileCheck %s
 subroutine testDoSimdLinear(int_array)
-        integer :: int_array(*)
+        integer :: int_array(:)
 !CHECK: not yet implemented: Unhandled clause LINEAR in SIMD construct
 !$omp do simd linear(int_array)
         do index_ = 1, 10

flang/test/Semantics/OpenMP/cray-pointer-usage.f90

@@ -4,6 +4,9 @@ subroutine test_cray_pointer_usage
   integer :: i
   real(8) :: var(*), pointee(2)
   pointer(ivar, var)
+  real(8) :: var2(10)
+  pointer(ivar2, var2)
+  ! ERROR: Whole assumed-size array 'var' may not appear here without subscripts
   ! ERROR: Cray Pointee 'var' may not appear in LINEAR clause
   ! ERROR: The list item 'var' specified without the REF 'linear-modifier' must be of INTEGER type
   ! ERROR: The list item `var` must be a dummy argument
@@ -17,9 +20,9 @@ subroutine test_cray_pointer_usage
     print *, var(1)
   !$omp end parallel
 
-  ! ERROR: Cray Pointee 'var' may not appear in PRIVATE clause, use Cray Pointer 'ivar' instead
-  !$omp parallel num_threads(2) default(none) private(var)
-    print *, var(1)
+  ! ERROR: Cray Pointee 'var2' may not appear in PRIVATE clause, use Cray Pointer 'ivar2' instead
+  !$omp parallel num_threads(2) default(none) private(var2)
+    print *, var2(1)
   !$omp end parallel
 
   ! ERROR: Cray Pointee 'var' may not appear in SHARED clause, use Cray Pointer 'ivar' instead

flang/test/Semantics/OpenMP/declare-mapper02.f90

@@ -6,5 +6,6 @@
 end type t1
 
 !ERROR: ABSTRACT derived type may not be used here
+!ERROR: Reference to object with abstract derived type 't1' must be polymorphic
 !$omp declare mapper(mm : t1::x) map(x, x%y)
 end

flang/test/Semantics/OpenMP/depend01.f90

@@ -20,7 +20,7 @@ program omp_depend
   !ERROR: 'a' in DEPEND clause must have a positive stride
   !ERROR: 'b' in DEPEND clause must have a positive stride
   !ERROR: 'b' in DEPEND clause is a zero size array section
-  !$omp task shared(x) depend(in: a(10:5:-1)) depend(in: b(5:10:-1))
+  !$omp task shared(x) depend(in: a(10:5:-1)) depend(in: b(5:10:-1, 2))
   print *, a(5:10), b
   !$omp end task
 

flang/test/Semantics/OpenMP/depend07.f90

@@ -0,0 +1,11 @@
+!RUN: %python %S/../test_errors.py %s %flang -fopenmp -fopenmp-version=45
+
+subroutine foo(x)
+  integer :: x(3, *)
+  !$omp task depend(in:x(:,5))
+  !$omp end task
+  !ERROR: Assumed-size array 'x' must have explicit final subscript upper bound value
+  !$omp task depend(in:x(5,:))
+  !$omp end task
+end
+