Go: Model log/slog as a logging sink

The standard-library structured logger `log/slog` (Go 1.21+) was not
modeled, so `go/log-injection` and `go/clear-text-logging` were blind to
any code that logs through it.

Model its logging functions and `*slog.Logger` methods — `Debug`, `Info`,
`Warn`, `Error`, their `Context` variants, and `Log`/`LogAttrs` — as
`log-injection` sinks (the kind that feeds `LoggerCall`, powering both
queries). Adds `log/slog` cases to the `LoggerCall` library test.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: sauyon

go/ql/lib/change-notes/2026-06-17-model-log-slog.md

@@ -0,0 +1,8 @@
+---
+category: minorAnalysis
+---
+* Added models for the `log/slog` package (Go 1.21+). Its logging functions and
+  `*slog.Logger` methods (`Debug`/`Info`/`Warn`/`Error`, their `Context`
+  variants, and `Log`/`LogAttrs`) are now recognized as logging sinks, so the
+  `go/log-injection` and `go/clear-text-logging` queries cover code that logs
+  through `slog`.

go/ql/lib/ext/log.slog.model.yml

@@ -0,0 +1,29 @@
+extensions:
+  - addsTo:
+      pack: codeql/go-all
+      extensible: sinkModel
+    data:
+      # Package-level convenience functions (msg string, args ...any).
+      - ["log/slog", "", False, "Debug", "", "", "Argument[0..1]", "log-injection", "manual"]
+      - ["log/slog", "", False, "Info", "", "", "Argument[0..1]", "log-injection", "manual"]
+      - ["log/slog", "", False, "Warn", "", "", "Argument[0..1]", "log-injection", "manual"]
+      - ["log/slog", "", False, "Error", "", "", "Argument[0..1]", "log-injection", "manual"]
+      # Context variants (ctx, msg string, args ...any).
+      - ["log/slog", "", False, "DebugContext", "", "", "Argument[1..2]", "log-injection", "manual"]
+      - ["log/slog", "", False, "InfoContext", "", "", "Argument[1..2]", "log-injection", "manual"]
+      - ["log/slog", "", False, "WarnContext", "", "", "Argument[1..2]", "log-injection", "manual"]
+      - ["log/slog", "", False, "ErrorContext", "", "", "Argument[1..2]", "log-injection", "manual"]
+      # Log/LogAttrs (ctx, level, msg string, args/attrs ...).
+      - ["log/slog", "", False, "Log", "", "", "Argument[2..3]", "log-injection", "manual"]
+      - ["log/slog", "", False, "LogAttrs", "", "", "Argument[2..3]", "log-injection", "manual"]
+      # Methods on *slog.Logger.
+      - ["log/slog", "Logger", True, "Debug", "", "", "Argument[0..1]", "log-injection", "manual"]
+      - ["log/slog", "Logger", True, "Info", "", "", "Argument[0..1]", "log-injection", "manual"]
+      - ["log/slog", "Logger", True, "Warn", "", "", "Argument[0..1]", "log-injection", "manual"]
+      - ["log/slog", "Logger", True, "Error", "", "", "Argument[0..1]", "log-injection", "manual"]
+      - ["log/slog", "Logger", True, "DebugContext", "", "", "Argument[1..2]", "log-injection", "manual"]
+      - ["log/slog", "Logger", True, "InfoContext", "", "", "Argument[1..2]", "log-injection", "manual"]
+      - ["log/slog", "Logger", True, "WarnContext", "", "", "Argument[1..2]", "log-injection", "manual"]
+      - ["log/slog", "Logger", True, "ErrorContext", "", "", "Argument[1..2]", "log-injection", "manual"]
+      - ["log/slog", "Logger", True, "Log", "", "", "Argument[2..3]", "log-injection", "manual"]
+      - ["log/slog", "Logger", True, "LogAttrs", "", "", "Argument[2..3]", "log-injection", "manual"]

go/ql/test/library-tests/semmle/go/concepts/LoggerCall/go.mod

@@ -1,6 +1,6 @@
 module codeql-go-tests/concepts/loggercall
 
-go 1.15
+go 1.21
 
 require (
 	github.com/golang/glog v1.2.5

go/ql/test/library-tests/semmle/go/concepts/LoggerCall/main.go

@@ -2,10 +2,12 @@ package main
 
 const fmt = "formatted %s string"
 const text = "test"
+const key = "key"
 
 var v []byte
 
 func main() {
 	glogTest(len(v))
 	stdlib()
+	slogTest()
 }

go/ql/test/library-tests/semmle/go/concepts/LoggerCall/slog.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"context"
+	"log/slog"
+)
+
+func slogTest() {
+	ctx := context.Background()
+	var logger *slog.Logger
+
+	// Methods on *slog.Logger: Debug/Info/Warn/Error(msg string, args ...any).
+	logger.Debug(text)       // $ logger=text
+	logger.Info(text)        // $ logger=text
+	logger.Warn(text)        // $ logger=text
+	logger.Error(text)       // $ logger=text
+	logger.Info(text, key, v) // $ logger=text logger=key logger=v
+
+	// Context variants: (ctx, msg string, args ...any).
+	logger.DebugContext(ctx, text)       // $ logger=text
+	logger.InfoContext(ctx, text)        // $ logger=text
+	logger.WarnContext(ctx, text)        // $ logger=text
+	logger.ErrorContext(ctx, text)       // $ logger=text
+	logger.InfoContext(ctx, text, key, v) // $ logger=text logger=key logger=v
+
+	// Log/LogAttrs: (ctx, level, msg string, args/attrs ...).
+	logger.Log(ctx, slog.LevelInfo, text, key, v) // $ logger=text logger=key logger=v
+	logger.LogAttrs(ctx, slog.LevelInfo, text)     // $ logger=text
+
+	// Package-level convenience functions.
+	slog.Debug(text)       // $ logger=text
+	slog.Info(text)        // $ logger=text
+	slog.Warn(text)        // $ logger=text
+	slog.Error(text)       // $ logger=text
+	slog.Info(text, key, v) // $ logger=text logger=key logger=v
+	slog.InfoContext(ctx, text, key, v) // $ logger=text logger=key logger=v
+	slog.Log(ctx, slog.LevelInfo, text) // $ logger=text
+	slog.LogAttrs(ctx, slog.LevelInfo, text) // $ logger=text
+}