[flang] Remove `ignoring all compiler directives` warning

[vdonaldson]

Summary

The explicit ignoring all compiler directives reminder warning is no
longer accurate. Any similar, more accurate message is best generated
by the front end (change pending).

[PeteSteinfeld]

I wonder if we should put out a TODO message when directives get passed to lowering. Otherwise, all builds and tests correctly and looks good.

flang/lib/Lower/Bridge.cpp

2001

Should we be emitting a TODO message here?

[vdonaldson]

In D148365#4269456, @PeteSteinfeld wrote:

I wonder if we should put out a TODO message when directives get passed to lowering. Otherwise, all builds and tests correctly and looks good.

No, that would have the identical problem that the warning message has, but would be worse because it would be fatal. It would be inaccurate for cases that are actually implemented and cases that don't have downstream component/s. A front end warning would serve the same purpose without these problems.

[vdonaldson]

https://reviews.llvm.org/D148365

flang/lib/Lower/Bridge.cpp

void run(Fortran::lower::pft::Program &pft) {
 
     // Primary translation pass.
     for (Fortran::lower::pft::Program::Units &u : pft.getUnits()) {
       std::visit(
           Fortran::common::visitors{
               [&](Fortran::lower::pft::FunctionLikeUnit &f) { lowerFunc(f); },
               [&](Fortran::lower::pft::ModuleLikeUnit &m) { lowerMod(m); },
               [&](Fortran::lower::pft::BlockDataUnit &b) {},
-              [&](Fortran::lower::pft::CompilerDirectiveUnit &d) {
-                setCurrentPosition(
-                    d.get<Fortran::parser::CompilerDirective>().source);
-                mlir::emitWarning(toLocation(),
-                                  "ignoring all compiler directives");
-              },
+              [&](Fortran::lower::pft::CompilerDirectiveUnit &d) {},
           },
           u);
     }
 
     /// Once all the code has been translated, create runtime type info
     /// global data structure for the derived types that have been
     /// processed.
     createGlobalOutsideOfFunctionLowering(

   void genFIR(const Fortran::parser::ForallConstructStmt &stmt) {
     genFIR(std::get<
                Fortran::common::Indirection<Fortran::parser::ConcurrentHeader>>(
                stmt.t)
                .value());
   }
 
   void genFIR(const Fortran::parser::CompilerDirective &) {
-    mlir::emitWarning(toLocation(), "ignoring all compiler directives");
+    // TODO
   }
 
   void genFIR(const Fortran::parser::OpenACCConstruct &acc) {
     mlir::OpBuilder::InsertPoint insertPt = builder->saveInsertionPoint();
     genOpenACCConstruct(*this, bridge.getSemanticsContext(), getEval(), acc);
     for (Fortran::lower::pft::Evaluation &e : getEval().getNestedEvaluations())
       genFIR(e);
     builder->restoreInsertionPoint(insertPt);

flang/test/Lower/compiler-directive.f90

-! RUN: bbc %s -o - 2>&1 | FileCheck %s
-! RUN: %flang_fc1 -emit-fir %s -o - 2>&1 | FileCheck %s
-
-! CHECK: ignoring all compiler directives
-
-MODULE test_mod
-  CONTAINS
-  SUBROUTINE foo()
-    REAL :: var
-  !DIR$ VECTOR ALIGNED
-    var = 1.
-  END SUBROUTINE foo
-END MODULE test_mod