[Ada] Cannot process -S -o with GNAT LLVM

[Pierre-Marie de Rodat]

This is fixed by recognizing -S in Scan_Compiler_Args and taking it into
account in Set_Output_Object_File_Name.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * opt.ads (Generate_Asm): New flag.
        * osint-c.adb (Set_Output_Object_File_Name): Accept any
        extension when generating assembly.
        * adabkend.adb (Scan_Compiler_Args): Recognize -S.
diff --git a/gcc/ada/adabkend.adb b/gcc/ada/adabkend.adb
--- a/gcc/ada/adabkend.adb
+++ b/gcc/ada/adabkend.adb
@@ -218,6 +218,9 @@ package body Adabkend is
                end case;
             end if;
 
+         elsif Switch_Chars (First .. Last) = "S" then
+            Generate_Asm := True;
+
          --  Ignore all other back-end switches
 
          elsif Is_Back_End_Switch (Switch_Chars) then


diff --git a/gcc/ada/opt.ads b/gcc/ada/opt.ads
--- a/gcc/ada/opt.ads
+++ b/gcc/ada/opt.ads
@@ -719,6 +719,10 @@ package Opt is
    --  the name is of the form .xxx, then to name.xxx where name is the source
    --  file name with extension stripped.
 
+   Generate_Asm : Boolean := False;
+   --  GNAT
+   --  True if generating assembly instead of an object file, via the -S switch
+
    Generate_C_Code : Boolean := False;
    --  GNAT, GNATBIND
    --  If True, the Cprint circuitry to generate C code output is activated.


diff --git a/gcc/ada/osint-c.adb b/gcc/ada/osint-c.adb
--- a/gcc/ada/osint-c.adb
+++ b/gcc/ada/osint-c.adb
@@ -480,6 +480,7 @@ package body Osint.C is
          or else
           (Name (NL - EL + Name'First .. Name'Last) /= Ext
              and then Name (NL - 2 + Name'First .. Name'Last) /= ".o"
+             and then not Generate_Asm
              and then
                (not Generate_C_Code
                   or else Name (NL - 2 + Name'First .. Name'Last) /= ".c"))