[Flang] Make all tests work with lit's internal shell

This patch removes REQUIRES: shell lines and updates the tests to not
need a shell, or adds REQUIRES lines for Linux where relevant. A lot of
these seem to have gotten introduced in
58c3f20, but many are no longer
relevant as these tests no longer use shell scripts.

There was one test (missing_newline.f90) that needed to be modified to
work. Lit doesn't recognize -ne correctly for echo and the options need
to be split into separate flags.

Reviewers: clementval, Meinersbur, kiranchandramohan, klausler

Reviewed By: clementval

Pull Request: #156115

Author: boomanaiden154

flang/docs/FlangDriver.md

@@ -360,10 +360,8 @@ be exactly what you want to test.  In fact, you can check these additional
 flags by using the `-###` compiler driver command line option.
 
 Lastly, you can use `! REQUIRES: <feature>` for tests that will only work when
-`<feature>` is available. For example, you can use`! REQUIRES: shell` to mark a
-test as only available on Unix-like systems (i.e. systems that contain a Unix
-shell). In practice this means that the corresponding test is skipped on
-Windows.
+`<feature>` is available. For example, you can use`! REQUIRES: system-linux` to
+mark a test as only available on Linux systems.
 
 ## Frontend Driver Plugins
 Plugins are an extension to the frontend driver that make it possible to run

flang/test/Driver/color-diagnostics-parse.f90

@@ -1,7 +1,7 @@
 ! Test the behaviors of -f{no-}color-diagnostics and -f{no-}diagnostics-color
 ! when emitting parsing diagnostics.
 ! Windows command prompt doesn't support ANSI escape sequences.
-! REQUIRES: shell
+! REQUIRES: system-linux
 
 ! RUN: not %flang %s -fcolor-diagnostics 2>&1 \
 ! RUN:     | FileCheck %s --check-prefix=CHECK_CD

flang/test/Driver/color-diagnostics-scan.f

@@ -1,7 +1,7 @@
 ! Test the behaviors of -f{no-}color-diagnostics and -f{no}-diagnostic-colors
 ! when emitting scanning diagnostics.
 ! Windows command prompt doesn't support ANSI escape sequences.
-! REQUIRES: shell
+! REQUIRES: system-linux
 
 ! RUN: not %flang %s -E -Werror -fcolor-diagnostics 2>&1 \
 ! RUN:     | FileCheck %s --check-prefix=CHECK_CD

flang/test/Driver/color-diagnostics-sema.f90

@@ -1,7 +1,7 @@
 ! Test the behaviors of -f{no-}color-diagnostics and -f{no}diagnostics-color
 ! when emitting semantic diagnostics.
 ! Windows command prompt doesn't support ANSI escape sequences.
-! REQUIRES: shell
+! REQUIRES: system-linux
 
 ! RUN: not %flang %s -fcolor-diagnostics 2>&1 \
 ! RUN:     | FileCheck %s --check-prefix=CHECK_CD

flang/test/Driver/color-diagnostics.f90

@@ -1,6 +1,6 @@
 ! Test the behaviors of -f{no-}color-diagnostics and -f{no}-diagnostics-color.
 ! Windows command prompt doesn't support ANSI escape sequences.
-! REQUIRES: shell
+! REQUIRES: system-linux
 
 ! RUN: not %flang %s -fcolor-diagnostics 2>&1 \
 ! RUN:     | FileCheck %s --check-prefix=CHECK_CD

flang/test/Lower/Intrinsics/selected_int_kind.f90

@@ -1,4 +1,3 @@
-! REQUIRES: shell
 ! RUN: bbc -emit-fir -hlfir=false %s -o - | FileCheck %s
 
 ! CHECK-LABEL: func.func @_QPselected_int_kind_test1(

flang/test/Lower/Intrinsics/selected_real_kind.f90

@@ -1,4 +1,3 @@
-! REQUIRES: shell
 ! RUN: bbc -emit-fir -hlfir=false %s -o - | FileCheck %s
 
 ! CHECK-LABEL: func.func @_QPselected_real_kind_test1(

flang/test/Lower/OpenMP/parallel-firstprivate-clause-scalar.f90

@@ -1,7 +1,6 @@
 ! This test checks lowering of `FIRSTPRIVATE` clause for scalar types.
 
 ! REQUIRES: x86-registered-target
-! REQUIRES: shell
 ! RUN: bbc -target x86_64-unknown-linux-gnu -fopenmp -emit-hlfir %s -o - \
 ! RUN: | FileCheck %s --check-prefixes=CHECK%if target=x86_64{{.*}} %{,CHECK-KIND10%}%if flang-supports-f128-math %{,CHECK-KIND16%}
 

flang/test/Lower/OpenMP/parallel-private-clause-str.f90

@@ -1,7 +1,6 @@
 ! This test checks lowering of OpenMP parallel Directive with
 ! `PRIVATE` clause present for strings
 
-! REQUIRES: shell
 ! RUN: bbc -fopenmp -emit-hlfir %s -o - \
 ! RUN: | FileCheck %s
 

flang/test/Lower/OpenMP/parallel-private-clause.f90

@@ -1,7 +1,6 @@
 ! This test checks lowering of OpenMP parallel Directive with
 ! `PRIVATE` clause present.
 
-! REQUIRES: shell
 ! RUN: bbc --use-desc-for-alloc=false -fopenmp -emit-hlfir %s -o - \
 ! RUN: | FileCheck %s --check-prefix=FIRDialect