C++: Add cpp/extraction-information query

cpp/ql/integration-tests/query-suite/cpp-code-scanning.qls.expected

@@ -52,5 +52,6 @@ ql/cpp/ql/src/Summary/LinesOfUserCode.ql
 ql/cpp/ql/src/Telemetry/CompilerErrors.ql
 ql/cpp/ql/src/Telemetry/DatabaseQuality.ql
 ql/cpp/ql/src/Telemetry/ExtractionMetrics.ql
+ql/cpp/ql/src/Telemetry/ExtractorInformation.ql
 ql/cpp/ql/src/Telemetry/MissingIncludes.ql
 ql/cpp/ql/src/Telemetry/SucceededIncludes.ql

cpp/ql/integration-tests/query-suite/cpp-security-and-quality.qls.expected

@@ -160,6 +160,7 @@ ql/cpp/ql/src/Summary/LinesOfUserCode.ql
 ql/cpp/ql/src/Telemetry/CompilerErrors.ql
 ql/cpp/ql/src/Telemetry/DatabaseQuality.ql
 ql/cpp/ql/src/Telemetry/ExtractionMetrics.ql
+ql/cpp/ql/src/Telemetry/ExtractorInformation.ql
 ql/cpp/ql/src/Telemetry/MissingIncludes.ql
 ql/cpp/ql/src/Telemetry/SucceededIncludes.ql
 ql/cpp/ql/src/jsf/4.06 Pre-Processing Directives/AV Rule 32.ql

cpp/ql/integration-tests/query-suite/cpp-security-extended.qls.expected

@@ -93,5 +93,6 @@ ql/cpp/ql/src/Summary/LinesOfUserCode.ql
 ql/cpp/ql/src/Telemetry/CompilerErrors.ql
 ql/cpp/ql/src/Telemetry/DatabaseQuality.ql
 ql/cpp/ql/src/Telemetry/ExtractionMetrics.ql
+ql/cpp/ql/src/Telemetry/ExtractorInformation.ql
 ql/cpp/ql/src/Telemetry/MissingIncludes.ql
 ql/cpp/ql/src/Telemetry/SucceededIncludes.ql

cpp/ql/src/Telemetry/DatabaseQuality.qll

@@ -0,0 +1,25 @@
+import cpp
+import codeql.util.ReportStats
+
+module CallTargetStats implements StatsSig {
+  private class RelevantCall extends Call {
+    RelevantCall() { this.getFile() = any(File f | f.fromSource() and exists(f.getRelativePath())) }
+  }
+
+  // We assume that calls with an implicit target are calls that could not be
+  // resolved. This is accurate in the vast majority of cases, but is inaccurate
+  // for calls that deliberately rely on implicitly declared functions.
+  private predicate hasImplicitTarget(RelevantCall call) {
+    call.getTarget().getADeclarationEntry().isImplicit()
+  }
+
+  int getNumberOfOk() { result = count(RelevantCall call | not hasImplicitTarget(call)) }
+
+  int getNumberOfNotOk() { result = count(RelevantCall call | hasImplicitTarget(call)) }
+
+  string getOkText() { result = "calls with call target" }
+
+  string getNotOkText() { result = "calls with missing call target" }
+}
+
+module CallTargetStatsReport = ReportStats<CallTargetStats>;

cpp/ql/src/Telemetry/ExtractorInformation.ql

@@ -0,0 +1,25 @@
+/**
+ * @name C/C++ extraction information
+ * @description Information about the extraction for a C/C++ database
+ * @kind metric
+ * @tags summary telemetry
+ * @id cpp/telemetry/extraction-information
+ */
+
+import cpp
+import DatabaseQuality
+
+from string key, float value
+where
+  (
+    CallTargetStatsReport::numberOfOk(key, value) or
+    CallTargetStatsReport::numberOfNotOk(key, value) or
+    CallTargetStatsReport::percentageOfOk(key, value)
+  ) and
+  /* Infinity */
+  value != 1.0 / 0.0 and
+  /* -Infinity */
+  value != -1.0 / 0.0 and
+  /* NaN */
+  value != 0.0 / 0.0
+select key, value