[flang][OpenMP] Fix typos in diagnostic messages, NFC (#154953)

Author: kparzysz

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

@@ -1198,13 +1198,13 @@ void OmpStructureChecker::Enter(const parser::OpenMPGroupprivate &x) {
 
     if (sym->has<AssocEntityDetails>()) {
       context_.SayWithDecl(*sym, arg.source,
-          "GROUPPRIVATE argument cannot be an an ASSOCIATE name"_err_en_US);
+          "GROUPPRIVATE argument cannot be an ASSOCIATE name"_err_en_US);
       continue;
     }
     if (auto *obj{sym->detailsIf<ObjectEntityDetails>()}) {
       if (obj->IsCoarray()) {
-        context_.Say(arg.source,
-            "GROUPPRIVATE argument cannot be an a coarray"_err_en_US);
+        context_.Say(
+            arg.source, "GROUPPRIVATE argument cannot be a coarray"_err_en_US);
         continue;
       }
       if (obj->init()) {
@@ -1215,7 +1215,7 @@ void OmpStructureChecker::Enter(const parser::OpenMPGroupprivate &x) {
     }
     if (sym->test(Symbol::Flag::InCommonBlock)) {
       context_.Say(arg.source,
-          "GROUPPRIVATE argument cannot be an a member of a common block"_err_en_US);
+          "GROUPPRIVATE argument cannot be a member of a common block"_err_en_US);
       continue;
     }
     if (!IsCommonBlock(*sym)) {

flang/test/Semantics/OpenMP/groupprivate.f90

@@ -14,7 +14,7 @@ subroutine f00
   integer, save :: y
   associate (z => y)
   block
-    !ERROR: GROUPPRIVATE argument cannot be an an ASSOCIATE name
+    !ERROR: GROUPPRIVATE argument cannot be an ASSOCIATE name
     !$omp groupprivate(z)
   end block
   end associate
@@ -25,7 +25,7 @@ module m01
 implicit none
 integer :: x, y
 common /some_block/ x
-!ERROR: GROUPPRIVATE argument cannot be an a member of a common block
+!ERROR: GROUPPRIVATE argument cannot be a member of a common block
 !$omp groupprivate(x)
 
 contains
@@ -42,6 +42,6 @@ subroutine f01
 module m02
 implicit none
 integer :: x(10)[*]
-!ERROR: GROUPPRIVATE argument cannot be an a coarray
+!ERROR: GROUPPRIVATE argument cannot be a coarray
 !$omp groupprivate(x)
 end module