[OPENMP]Fix PR48387: disable warning messages caused by internal conversions.

Compiler needs to convert some of the loop iteration
variables/conditions to different types for better codegen and it may
lead to spurious warning messages about implicit signed/unsigned
conversions.

Differential Revision: https://reviews.llvm.org/D92655

Author: alexey-bataev

clang/lib/Sema/SemaOpenMP.cpp

@@ -4196,6 +4196,7 @@ static OMPCapturedExprDecl *buildCaptureDecl(Sema &S, IdentifierInfo *Id,
   if (!WithInit)
     CED->addAttr(OMPCaptureNoInitAttr::CreateImplicit(C));
   S.CurContext->addHiddenDecl(CED);
+  Sema::TentativeAnalysisScope Trap(S);
   S.AddInitializerToDecl(CED, Init, /*DirectInit=*/false);
   return CED;
 }
@@ -7580,6 +7581,7 @@ std::pair<Expr *, Expr *> OpenMPIterationSpaceChecker::buildMinMaxValues(
   if (!Diff.isUsable())
     return std::make_pair(nullptr, nullptr);
 
+  Sema::TentativeAnalysisScope Trap(SemaRef);
   Diff = SemaRef.ActOnFinishFullExpr(Diff.get(), /*DiscardedValue=*/false);
   if (!Diff.isUsable())
     return std::make_pair(nullptr, nullptr);

clang/test/OpenMP/for_ast_print.cpp

@@ -1,8 +1,8 @@
-// RUN: %clang_cc1 -verify -fopenmp -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -verify -fopenmp -ast-print %s -Wsign-conversion | FileCheck %s
 // RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
 // RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
 
-// RUN: %clang_cc1 -verify -fopenmp-simd -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -verify -fopenmp-simd -ast-print %s -Wsign-conversion | FileCheck %s
 // RUN: %clang_cc1 -fopenmp-simd -x c++ -std=c++11 -emit-pch -o %t %s
 // RUN: %clang_cc1 -fopenmp-simd -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
 // expected-no-diagnostics
@@ -223,9 +223,9 @@ int main(int argc, char **argv) {
 // CHECK: static int a;
 #pragma omp for schedule(guided, argc) reduction(+:argv[0][:1]) order(concurrent)
   // CHECK-NEXT: #pragma omp for schedule(guided, argc) reduction(+: argv[0][:1]) order(concurrent)
-  for (int i = 0; i < 2; ++i)
+  for (int i = argc; i < c; ++i)
     a = 2;
-// CHECK-NEXT: for (int i = 0; i < 2; ++i)
+// CHECK-NEXT: for (int i = argc; i < c; ++i)
 // CHECK-NEXT: a = 2;
 #pragma omp parallel
 #pragma omp for private(argc, b), firstprivate(argv, c), lastprivate(d, f) collapse(3) schedule(auto) ordered nowait linear(g:-1) reduction(task, +:e)