Swift: add tracer config

swift/BUILD.bazel

@@ -17,6 +17,12 @@ pkg_files(
     prefix = "tools",
 )
 
+pkg_files(
+    name = "tracing-config",
+    srcs = ["tools/tracing-config.lua"],
+    prefix = "tools",
+)
+
 pkg_files(
     name = "manifest",
     srcs = ["codeql-extractor.yml"],
@@ -28,6 +34,7 @@ pkg_filegroup(
         ":dbscheme",
         ":manifest",
         ":qltest",
+        ":tracing-config",
     ],
     visibility = ["//visibility:public"],
 )

swift/tools/tracing-config.lua

@@ -0,0 +1,33 @@
+function RegisterExtractorPack(id)
+    local extractorDirectory = GetPlatformToolsDirectory()
+    local relativeSwiftExtractor = extractorDirectory .. 'extractor'
+    local swiftExtractor = AbsolutifyExtractorPath(id, relativeSwiftExtractor)
+
+    function SwiftMatcher(compilerName, compilerPath, compilerArguments, lang)
+        -- Only match binaries names `swift-frontend`
+        if compilerName ~= 'swift-frontend' then return nil end
+        -- Skip the invocation in case it's not called in `-frontend` mode
+        if compilerArguments.argv[1] ~= '-frontend' then return nil end
+
+        -- Drop the `-frontend` argument
+        table.remove(compilerArguments.argv, 1)
+
+        -- Skip "info" queries in case there is nothing to extract
+        if compilerArguments.argv[1] == '-print-target-info' then return nil end
+        if compilerArguments.argv[1] == '-emit-supported-features' then return nil end
+
+        -- Skip actions in which we cannot extract anything
+        if compilerArguments.argv[1] == '-merge-modules' then return nil end
+
+        return {
+            trace = true,
+            replace = false,
+            invocations = {{path = swiftExtractor, arguments = compilerArguments}}
+        }
+    end
+    return { SwiftMatcher }
+end
+
+-- Return a list of minimum supported versions of the configuration file format
+-- return one entry per supported major version.
+function GetCompatibleVersions() return {'1.0.0'} end