[Flang][Driver] Enable config file options (#100343)

Config files provide a facility to invoke the compiler with a predefined
set of options. The patch only enables these options in the flang
driver. Functionality was always there.

(cherry picked from commit 8a77961)

clang/include/clang/Driver/Options.td

@@ -1165,19 +1165,19 @@ def client__name : JoinedOrSeparate<["-"], "client_name">;
 def combine : Flag<["-", "--"], "combine">, Flags<[NoXarchOption, Unsupported]>;
 def compatibility__version : JoinedOrSeparate<["-"], "compatibility_version">;
 def config : Joined<["--"], "config=">, Flags<[NoXarchOption]>,
-  Visibility<[ClangOption, CLOption, DXCOption]>, MetaVarName<"<file>">,
+  Visibility<[ClangOption, CLOption, DXCOption, FlangOption]>, MetaVarName<"<file>">,
   HelpText<"Specify configuration file">;
-def : Separate<["--"], "config">, Alias<config>;
+def : Separate<["--"], "config">, Visibility<[ClangOption, CLOption, DXCOption, FlangOption]>, Alias<config>;
 def no_default_config : Flag<["--"], "no-default-config">,
-  Flags<[NoXarchOption]>, Visibility<[ClangOption, CLOption, DXCOption]>,
+  Flags<[NoXarchOption]>, Visibility<[ClangOption, CLOption, DXCOption, FlangOption]>,
   HelpText<"Disable loading default configuration files">;
 def config_system_dir_EQ : Joined<["--"], "config-system-dir=">,
   Flags<[NoXarchOption, HelpHidden]>,
-  Visibility<[ClangOption, CLOption, DXCOption]>,
+  Visibility<[ClangOption, CLOption, DXCOption, FlangOption]>,
   HelpText<"System directory for configuration files">;
 def config_user_dir_EQ : Joined<["--"], "config-user-dir=">,
   Flags<[NoXarchOption, HelpHidden]>,
-  Visibility<[ClangOption, CLOption, DXCOption]>,
+  Visibility<[ClangOption, CLOption, DXCOption, FlangOption]>,
   HelpText<"User directory for configuration files">;
 def coverage : Flag<["-", "--"], "coverage">, Group<Link_Group>,
   Visibility<[ClangOption, CLOption]>;

flang/test/Driver/Inputs/config-1.cfg

@@ -0,0 +1 @@
+-flto

flang/test/Driver/Inputs/config-2.cfg

@@ -0,0 +1 @@
+-fno-signed-zeros

flang/test/Driver/Inputs/config-2a.cfg

@@ -0,0 +1 @@
+-fopenmp

flang/test/Driver/Inputs/config-6.cfg

@@ -0,0 +1 @@
+-fstack-arrays

flang/test/Driver/Inputs/config/config-4.cfg

@@ -0,0 +1 @@
+-O3

flang/test/Driver/Inputs/config2/config-4.cfg

@@ -0,0 +1 @@
+-ffp-contract=fast

flang/test/Driver/config-file.f90

@@ -0,0 +1,63 @@
+!--- Config file (full path) in output of -###
+!
+! RUN: %flang --config-system-dir=%S/Inputs/config --config-user-dir=%S/Inputs/config2 -o /dev/null -v 2>&1 | FileCheck %s -check-prefix CHECK-DIRS
+! CHECK-DIRS: System configuration file directory: {{.*}}/Inputs/config
+! CHECK-DIRS: User configuration file directory: {{.*}}/Inputs/config2
+!
+!--- Config file (full path) in output of -###
+!
+! RUN: %flang --config %S/Inputs/config-1.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-HHH
+! RUN: %flang --config=%S/Inputs/config-1.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-HHH
+! CHECK-HHH: Configuration file: {{.*}}Inputs{{.}}config-1.cfg
+! CHECK-HHH: -flto
+!
+!
+!--- Config file (full path) in output of -v
+!
+! RUN: %flang --config %S/Inputs/config-1.cfg -S %s -o /dev/null -v 2>&1 | FileCheck %s -check-prefix CHECK-V
+! CHECK-V: Configuration file: {{.*}}Inputs{{.}}config-1.cfg
+! CHECK-V: -flto
+!
+!--- Config file in output of -###
+!
+! RUN: %flang --config-system-dir=%S/Inputs --config-user-dir= --config config-1.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-HHH2
+! CHECK-HHH2: Configuration file: {{.*}}Inputs{{.}}config-1.cfg
+! CHECK-HHH2: -flto
+!
+!--- Config file in output of -v
+!
+! RUN: %flang --config-system-dir=%S/Inputs --config-user-dir= --config config-1.cfg -S %s -o /dev/null -v 2>&1 | FileCheck %s -check-prefix CHECK-V2
+! CHECK-V2: Configuration file: {{.*}}Inputs{{.}}config-1.cfg
+! CHECK-V2: -flto
+!
+!--- Nested config files
+!
+! RUN: %flang --config-system-dir=%S/Inputs --config-user-dir= --config config-2.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NESTED
+! CHECK-NESTED: Configuration file: {{.*}}Inputs{{.}}config-2.cfg
+! CHECK-NESTED: -fno-signed-zeros
+!
+! RUN: %flang --config-system-dir=%S/Inputs --config-user-dir=%S/Inputs/config --config config-6.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NESTED2
+! CHECK-NESTED2: Configuration file: {{.*}}Inputs{{.}}config-6.cfg
+! CHECK-NESTED2: -fstack-arrays
+!
+!
+! RUN: %flang --config %S/Inputs/config-2a.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NESTEDa
+! CHECK-NESTEDa: Configuration file: {{.*}}Inputs{{.}}config-2a.cfg
+! CHECK-NESTEDa: -fopenmp
+!
+! RUN: %flang --config-system-dir=%S/Inputs --config-user-dir= --config config-2a.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NESTED2a
+! CHECK-NESTED2a: Configuration file: {{.*}}Inputs{{.}}config-2a.cfg
+! CHECK-NESTED2a: -fopenmp
+!
+!--- User directory is searched first.
+!
+! RUN: %flang --config-system-dir=%S/Inputs/config --config-user-dir=%S/Inputs/config2 --config config-4.cfg -S %s -o /dev/null -v 2>&1 | FileCheck %s -check-prefix CHECK-PRECEDENCE
+! CHECK-PRECEDENCE: Configuration file: {{.*}}Inputs{{.}}config2{{.}}config-4.cfg
+! CHECK-PRECEDENCE: -ffp-contract=fast
+!
+!--- Multiple configuration files can be specified.
+! RUN: %flang --config-system-dir=%S/Inputs/config --config-user-dir= --config config-4.cfg --config %S/Inputs/config2/config-4.cfg -S %s -o /dev/null -v 2>&1 | FileCheck %s -check-prefix CHECK-TWO-CONFIGS
+! CHECK-TWO-CONFIGS: Configuration file: {{.*}}Inputs{{.}}config{{.}}config-4.cfg
+! CHECK-TWO-CONFIGS-NEXT: Configuration file: {{.*}}Inputs{{.}}config2{{.}}config-4.cfg
+! CHECK-TWO-CONFIGS: -ffp-contract=fast
+! CHECK-TWO-CONFIGS: -O3