Add support for --restricted-to-languages to gnatcov coverage

To avoid spurious warnings such as "no SID file found for unit <bla>" at
gnatcov coverage time for units in a language that was ignored at
instrumentation time by using the --restricted-to-languages switch.

Author: Jugst3r

testsuite/tests/instr-cov/main_autodump/disabled_lang/test.py

@@ -22,7 +22,11 @@
     covlevel="stmt",
     mains=["main"],
     extra_instr_args=["--restricted-to-languages=C"],
-    extra_coverage_args=["-axcov", "--output-dir=xcov"],
+    extra_coverage_args=[
+        "-axcov",
+        "--output-dir=xcov",
+        "--restricted-to-languages=C",
+    ],
     trace_mode="src",
 )
 check_xcov_reports("xcov", {"tested.c.xcov": {"+": {5}, "-": {7}}})
@@ -39,7 +43,11 @@
     covlevel="stmt",
     mains=["main"],
     extra_instr_args=["--restricted-to-languages=Ada"],
-    extra_coverage_args=["-axcov", "--output-dir=xcov"],
+    extra_coverage_args=[
+        "-axcov",
+        "--output-dir=xcov",
+        "--restricted-to-languages=Ada",
+    ],
     trace_mode="src",
 )
 check_xcov_reports(

tools/gnatcov/command_line.ads

@@ -1586,7 +1586,8 @@ package Command_Line is
            & " C and C++. Note that main units of other languages may still be"
            & " instrumented to dump the coverage state to trace files.",
          Commands                => (Cmd_Setup
-                                     | Cmd_Instrument_Project => True,
+                                     | Cmd_Instrument_Project
+                                     | Cmd_Coverage => True,
                                      others                   => False),
          Internal                => False,
          Accepts_Comma_Separator => True),

tools/gnatcov/project.adb

@@ -366,6 +366,11 @@ package body Project is
       if Unit.Warned_About_Missing_Info
          or else (Currently_Accepted_Trace_Kind = Binary_Trace_File
                   and then Unit.Language = CPP_Language)
+
+        --  Ignore units in a language that is ignored through the
+        --  --restricted-to-languages switch.
+
+        or else not Src_Enabled_Languages (Unit.Language)
       then
          return;
       end if;

tools/gnatcov/setup_rts.adb

@@ -121,7 +121,8 @@ package body Setup_RTS is
    --  Load the project file at Project_File using the Target/RTS/Config_File
    --  parameters, then try to guess the profile of the actual runtime in
    --  effect (Auto_RTS_Profile) and determine the support for libraries for
-   --  this configuration (Lib_Support).
+   --  this configuration (Lib_Support). Pass Db_Dir as an additional knowledge
+   --  base. when creating the configuration file.
    --
    --  Set Actual_Target, Actual_RTS_Dir and Actual_RTS_Name to the actual
    --  target/RTS names for the loaded project: they can be different from

tools/gnatcov/switches.ads

@@ -223,8 +223,8 @@ package Switches is
 
    Src_Enabled_Languages : array (Src_Supported_Language) of Boolean :=
      (others => False);
-   --  List of languages for which source files should be instrumented.
-   --  Initialized during command line arguments parsing.
+   --  List of languages for which coverage analysis is enabled. Initialized
+   --  during command line arguments parsing.
 
    Builtin_Support : array (Src_Supported_Language) of Boolean :=
      (others => True);