From d691c3215f7ec607d7c098213f0dfb79544054bd Mon Sep 17 00:00:00 2001
From: Geoffrey White <40627776+geoffw0@users.noreply.github.com>
Date: Tue, 21 Oct 2025 11:59:56 +0100
Subject: [PATCH 1/3] Rust: Add expressions with unknown type metric (expected
 by DCA).

---
 rust/ql/src/queries/telemetry/DatabaseQuality.qll | 15 +++++++++++++++
 .../src/queries/telemetry/ExtractorInformation.ql |  5 ++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/rust/ql/src/queries/telemetry/DatabaseQuality.qll b/rust/ql/src/queries/telemetry/DatabaseQuality.qll
index 15826fec4c45..0b874a9b9cef 100644
--- a/rust/ql/src/queries/telemetry/DatabaseQuality.qll
+++ b/rust/ql/src/queries/telemetry/DatabaseQuality.qll
@@ -6,6 +6,7 @@
 
 import rust
 import codeql.util.ReportStats
+import codeql.rust.internal.TypeInference as TypeInference
 
 module CallTargetStats implements StatsSig {
   int getNumberOfOk() { result = count(CallExprBase c | exists(c.getStaticTarget())) }
@@ -41,6 +42,20 @@ module MacroCallTargetStats implements StatsSig {
   string getNotOkText() { result = "macro calls with missing call target" }
 }
 
+private predicate hasGoodType(Expr e) { exists(TypeInference::inferType(e, _)) }
+
+module ExprTypeStats implements StatsSig {
+  int getNumberOfOk() { result = count(Expr e | e.fromSource() and hasGoodType(e)) }
+
+  int getNumberOfNotOk() { result = count(Expr e | e.fromSource() and not hasGoodType(e)) }
+
+  string getOkText() { result = "expressions with known type" }
+
+  string getNotOkText() { result = "expressions with unknown type" }
+}
+
 module CallTargetStatsReport = ReportStats<CallTargetStats>;
 
 module MacroCallTargetStatsReport = ReportStats<MacroCallTargetStats>;
+
+module ExprTypeStatsReport = ReportStats<ExprTypeStats>;
diff --git a/rust/ql/src/queries/telemetry/ExtractorInformation.ql b/rust/ql/src/queries/telemetry/ExtractorInformation.ql
index f61dfe515a9e..ab18ecf489f3 100644
--- a/rust/ql/src/queries/telemetry/ExtractorInformation.ql
+++ b/rust/ql/src/queries/telemetry/ExtractorInformation.ql
@@ -54,7 +54,10 @@ where
     CallTargetStatsReport::percentageOfOk(key, value) or
     MacroCallTargetStatsReport::numberOfOk(key, value) or
     MacroCallTargetStatsReport::numberOfNotOk(key, value) or
-    MacroCallTargetStatsReport::percentageOfOk(key, value)
+    MacroCallTargetStatsReport::percentageOfOk(key, value) or
+    ExprTypeStatsReport::numberOfOk(key, value) or
+    ExprTypeStatsReport::numberOfNotOk(key, value) or
+    ExprTypeStatsReport::percentageOfOk(key, value)
   ) and
   /* Infinity */
   value != 1.0 / 0.0 and

From 751d62aefbc9a70f0ca8cb0d1c17222f1d46f2e1 Mon Sep 17 00:00:00 2001
From: Geoffrey White <40627776+geoffw0@users.noreply.github.com>
Date: Tue, 21 Oct 2025 13:29:14 +0100
Subject: [PATCH 2/3] Rust: Add the metric to rust/diagnostic/database-quality
 (with a very low threshold for the time being).

---
 rust/ql/src/queries/telemetry/DatabaseQualityDiagnostics.ql | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/rust/ql/src/queries/telemetry/DatabaseQualityDiagnostics.ql b/rust/ql/src/queries/telemetry/DatabaseQualityDiagnostics.ql
index 63fb1e4c6cc5..02933b3bd5f6 100644
--- a/rust/ql/src/queries/telemetry/DatabaseQualityDiagnostics.ql
+++ b/rust/ql/src/queries/telemetry/DatabaseQualityDiagnostics.ql
@@ -13,6 +13,8 @@ private predicate diagnostic(string msg, float value, float threshold) {
   CallTargetStatsReport::percentageOfOk(msg, value) and threshold = 50
   or
   MacroCallTargetStatsReport::percentageOfOk(msg, value) and threshold = 50
+  or
+  ExprTypeStatsReport::percentageOfOk(msg, value) and threshold = 20
 }
 
 private string getDbHealth() {

From 7da00b3e9d032bc37e05aeabd2c2ab0da1871e8b Mon Sep 17 00:00:00 2001
From: Geoffrey White <40627776+geoffw0@users.noreply.github.com>
Date: Tue, 21 Oct 2025 13:33:17 +0100
Subject: [PATCH 3/3] Rust: Change note.

---
 .../change-notes/2025-10-21-database-quality-diagnostic.md    | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 rust/ql/src/change-notes/2025-10-21-database-quality-diagnostic.md

diff --git a/rust/ql/src/change-notes/2025-10-21-database-quality-diagnostic.md b/rust/ql/src/change-notes/2025-10-21-database-quality-diagnostic.md
new file mode 100644
index 000000000000..322bdb7c5ab1
--- /dev/null
+++ b/rust/ql/src/change-notes/2025-10-21-database-quality-diagnostic.md
@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The "Low Rust analysis quality" query (`rust/diagnostic/database-quality`), used by the tool status page, has been extended with a measure of successful type inference.