[pushed] diagnostics: SARIF output: capture unlabelled secondary locations

diff --git a/gcc/diagnostic-format-sarif.cc b/gcc/diagnostic-format-sarif.cc
index 2232883281b..7c2e96f4f74 100644
--- a/gcc/diagnostic-format-sarif.cc
+++ b/gcc/diagnostic-format-sarif.cc
@@ -323,7 +323,11 @@  public:
     {
      /* Process a #include relationship where m_location_obj
 	was #included-d at m_where.  */
-     included_from
+     included_from,
+
+     /* Process a location_t that was added as a secondary location
+	to a rich_location without a label.  */
+     unlabelled_secondary_location
     };
 
     worklist_item (sarif_location &location_obj,
@@ -369,6 +373,7 @@  private:
 
   std::list<worklist_item> m_worklist;
   std::map<location_t, sarif_location *> m_included_from_locations;
+  std::map<location_t, sarif_location *> m_unlabelled_secondary_locations;
 };
 
 /* Subclass of sarif_object for SARIF "result" objects
@@ -559,6 +564,7 @@  public:
    - diagnostic groups (see limitations below)
    - logical locations (e.g. cfun)
    - labelled ranges (as annotations)
+   - secondary ranges without labels (as related locations)
 
    Known limitations:
    - GCC supports one-deep nesting of diagnostics (via auto_diagnostic_group),
@@ -566,9 +572,6 @@  public:
      diagnostics (e.g. we ignore fix-it hints on them)
    - although we capture command-line arguments (section 3.20.2), we don't
      yet capture response files.
-   - doesn't capture secondary locations within a rich_location
-     (perhaps we should use the "relatedLocations" property: SARIF v2.1.0
-     section 3.27.22)
    - doesn't capture "artifact.encoding" property
      (SARIF v2.1.0 section 3.24.9).
    - doesn't capture hashes of the source files
@@ -987,6 +990,34 @@  sarif_location_manager::process_worklist_item (sarif_builder &builder,
 	   *this);
       }
       break;
+    case worklist_item::kind::unlabelled_secondary_location:
+      {
+	sarif_location &primary_loc_obj = item.m_location_obj;
+	sarif_location *secondary_loc_obj = nullptr;
+	auto iter = m_unlabelled_secondary_locations.find (item.m_where);
+	if (iter != m_unlabelled_secondary_locations.end ())
+	  secondary_loc_obj = iter->second;
+	else
+	  {
+	    std::unique_ptr<sarif_location> new_loc_obj
+	      = builder.make_location_object
+		  (*this,
+		   item.m_where,
+		   diagnostic_artifact_role::scanned_file);
+	    secondary_loc_obj = new_loc_obj.get ();
+	    add_related_location (std::move (new_loc_obj));
+	    auto kv
+	      = std::pair<location_t, sarif_location *> (item.m_where,
+							 secondary_loc_obj);
+	    m_unlabelled_secondary_locations.insert (kv);
+	  }
+	gcc_assert (secondary_loc_obj);
+	primary_loc_obj.lazily_add_relationship
+	  (*secondary_loc_obj,
+	   location_relationship_kind::relevant,
+	   *this);
+      }
+      break;
     }
 }
 
@@ -1739,18 +1770,19 @@  sarif_builder::make_location_object (sarif_location_manager &loc_mgr,
   /* "logicalLocations" property (SARIF v2.1.0 section 3.28.4).  */
   set_any_logical_locs_arr (*location_obj, logical_loc);
 
-  /* "annotations" property (SARIF v2.1.0 section 3.28.6).  */
+  /* Handle labelled ranges and/or secondary locations.  */
   {
-    /* Create annotations for any labelled ranges.  */
     std::unique_ptr<json::array> annotations_arr = nullptr;
     for (unsigned int i = 0; i < rich_loc.get_num_locations (); i++)
       {
 	const location_range *range = rich_loc.get_range (i);
+	bool handled = false;
 	if (const range_label *label = range->m_label)
 	  {
 	    label_text text = label->get_text (i);
 	    if (text.get ())
 	      {
+		/* Create annotations for any labelled ranges.  */
 		location_t range_loc = rich_loc.get_loc (i);
 		auto region
 		  = maybe_make_region_object (range_loc,
@@ -1762,11 +1794,21 @@  sarif_builder::make_location_object (sarif_location_manager &loc_mgr,
 		    region->set<sarif_message>
 		      ("message", make_message_object (text.get ()));
 		    annotations_arr->append<sarif_region> (std::move (region));
+		    handled = true;
 		  }
 	      }
 	  }
+
+	/* Add related locations for any secondary locations in RICH_LOC
+	   that don't have labels (and thus aren't added to "annotations"). */
+	if (i > 0 && !handled)
+	  loc_mgr.add_relationship_to_worklist
+	    (*location_obj.get (),
+	     sarif_location_manager::worklist_item::kind::unlabelled_secondary_location,
+	     range->m_loc);
       }
     if (annotations_arr)
+      /* "annotations" property (SARIF v2.1.0 section 3.28.6).  */
       location_obj->set<json::array> ("annotations",
 				      std::move (annotations_arr));
   }
diff --git a/gcc/testsuite/gcc.dg/sarif-output/missing-semicolon.c b/gcc/testsuite/gcc.dg/sarif-output/missing-semicolon.c
new file mode 100644
index 00000000000..426b930cfc2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/sarif-output/missing-semicolon.c
@@ -0,0 +1,22 @@ 
+/* { dg-do compile } */
+/* { dg-options "-fdiagnostics-format=sarif-file" } */
+
+/* Verify that SARIF output can capture secondary locations
+   relating to a diagnostic.  */
+
+int missing_semicolon (void)
+{
+  return 42
+}
+
+/* We expect a failing compile due to the error, but the use of 
+   -fdiagnostics-format=sarif-file means there should be no output to stderr.
+   DejaGnu injects this message; ignore it:
+   { dg-prune-output "exit status is 1" } */
+
+/* Verify that some JSON was written to a file with the expected name:
+   { dg-final { verify-sarif-file } } */
+
+/* Use a Python script to verify various properties about the generated
+   .sarif file:
+   { dg-final { run-sarif-pytest missing-semicolon.c "test-missing-semicolon.py" } } */
diff --git a/gcc/testsuite/gcc.dg/sarif-output/sarif.py b/gcc/testsuite/gcc.dg/sarif-output/sarif.py
index 54c96a006b6..a34678791ac 100644
--- a/gcc/testsuite/gcc.dg/sarif-output/sarif.py
+++ b/gcc/testsuite/gcc.dg/sarif-output/sarif.py
@@ -14,6 +14,9 @@  def sarif_from_env():
 def get_location_artifact_uri(location):
     return location['physicalLocation']['artifactLocation']['uri']
 
+def get_location_physical_region(location):
+    return location['physicalLocation']['region']
+
 def get_location_snippet_text(location):
     return location['physicalLocation']['contextRegion']['snippet']['text']
 
diff --git a/gcc/testsuite/gcc.dg/sarif-output/test-missing-semicolon.py b/gcc/testsuite/gcc.dg/sarif-output/test-missing-semicolon.py
new file mode 100644
index 00000000000..795980d88cc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/sarif-output/test-missing-semicolon.py
@@ -0,0 +1,79 @@ 
+from sarif import *
+
+import pytest
+
+@pytest.fixture(scope='function', autouse=True)
+def sarif():
+    return sarif_from_env()
+
+def test_basics(sarif):
+    schema = sarif['$schema']
+    assert schema == "https://raw.githubusercontent.com/oasis-tcs/sarif-spec/master/Schemata/sarif-schema-2.1.0.json"
+
+    version = sarif['version']
+    assert version == "2.1.0"
+
+def test_location_relationships(sarif):
+    runs = sarif['runs']
+    run = runs[0]
+    results = run['results']
+
+    # We expect a single error with a secondary location and a fix-it hint.
+    #
+    # The textual form of the diagnostic would look like this:
+    #  . PATH/missing-semicolon.c: In function 'missing_semicolon':
+    #  . PATH/missing-semicolon.c:19:12: error: expected ';' before '}' token
+    #  .    19 |   return 42
+    #  .       |            ^
+    #  .       |            ;
+    #  .    20 | }
+    #  .       | ~           
+    assert len(results) == 1
+    
+    result = results[0]
+    assert result['level'] == 'error'
+    assert result['message']['text'] == "expected ';' before '}' token"
+    locations = result['locations']
+    assert len(locations) == 1
+
+    location = locations[0]
+    assert get_location_artifact_uri(location).endswith('missing-semicolon.c')
+    assert get_location_snippet_text(location) == '  return 42\n'
+    assert get_location_physical_region(location)['startLine'] == 9
+    assert get_location_physical_region(location)['startColumn'] == 12
+    assert get_location_physical_region(location)['endColumn'] == 13
+
+    # We don't expect the secondary location to have a relationship back
+    # to the primary location, and so the primary doesn't get an id.
+    assert 'id' not in location
+
+    # We expect the primary location to reference the secondary location.
+    assert len(location['relationships']) == 1
+    assert location['relationships'][0]['target'] == 0
+    assert location['relationships'][0]['kinds'] == ['relevant']
+
+    # We expect one related location, for the closing brace on the next line
+    relatedLocations = result['relatedLocations']
+    assert len(relatedLocations) == 1
+
+    rel_loc = relatedLocations[0]
+    assert rel_loc['id'] == 0
+    assert get_location_artifact_uri(rel_loc).endswith('missing-semicolon.c')
+    assert get_location_snippet_text(rel_loc) == '}\n'
+    assert get_location_physical_region(rel_loc)['startLine'] == 10
+    assert get_location_physical_region(rel_loc)['startColumn'] == 1
+    assert get_location_physical_region(rel_loc)['endColumn'] == 2
+    assert 'relatedLocations' not in rel_loc
+    assert 'message' not in rel_loc
+
+    # We expect one fix-it hint representing an insertion of ';'
+    assert len(result['fixes']) == 1
+    assert len(result['fixes'][0]['artifactChanges']) == 1
+    change = result['fixes'][0]['artifactChanges'][0]
+    assert change['artifactLocation']['uri'].endswith('missing-semicolon.c')
+    assert len(change['replacements']) == 1
+    replacement = change['replacements'][0]
+    assert replacement['deletedRegion']['startLine'] == 9
+    assert replacement['deletedRegion']['startColumn'] == 12
+    assert replacement['deletedRegion']['endColumn'] == 12
+    assert replacement['insertedContent']['text'] == ';'