[flang][OpenMP] Fix crash in unparse-with-symbols for CRITICAL (#151962)

Author: kparzysz

flang/lib/Semantics/unparse-with-symbols.cpp

@@ -70,6 +70,33 @@ class SymbolDumpVisitor {
     currStmt_ = std::nullopt;
   }
 
+  bool Pre(const parser::OmpCriticalDirective &x) {
+    currStmt_ = x.source;
+    return true;
+  }
+  void Post(const parser::OmpCriticalDirective &) { currStmt_ = std::nullopt; }
+
+  bool Pre(const parser::OmpEndCriticalDirective &x) {
+    currStmt_ = x.source;
+    return true;
+  }
+  void Post(const parser::OmpEndCriticalDirective &) {
+    currStmt_ = std::nullopt;
+  }
+
+  // Directive arguments can be objects with symbols.
+  bool Pre(const parser::OmpBeginDirective &x) {
+    currStmt_ = x.source;
+    return true;
+  }
+  void Post(const parser::OmpBeginDirective &) { currStmt_ = std::nullopt; }
+
+  bool Pre(const parser::OmpEndDirective &x) {
+    currStmt_ = x.source;
+    return true;
+  }
+  void Post(const parser::OmpEndDirective &) { currStmt_ = std::nullopt; }
+
 private:
   std::optional<SourceName> currStmt_; // current statement we are processing
   std::multimap<const char *, const Symbol *> symbols_; // location to symbol

flang/test/Parser/OpenMP/critical-unparse-with-symbols.f90

@@ -0,0 +1,21 @@
+!RUN: %flang_fc1 -fdebug-unparse-with-symbols -fopenmp -fopenmp-version=50 %s | FileCheck --ignore-case --check-prefix="UNPARSE" %s
+
+subroutine f
+  implicit none
+  integer :: x
+  !$omp critical(c)
+  x = 0
+  !$omp end critical(c)
+end
+
+!UNPARSE: !DEF: /f (Subroutine) Subprogram
+!UNPARSE: subroutine f
+!UNPARSE:  implicit none
+!UNPARSE:  !DEF: /f/x ObjectEntity INTEGER(4)
+!UNPARSE:  integer x
+!UNPARSE: !$omp critical (c)
+!UNPARSE:  !REF: /f/x
+!UNPARSE:  x = 0
+!UNPARSE: !$omp end critical (c)
+!UNPARSE: end subroutine
+