C++: Extract the expanded compiler arguments

cpp/downgrades/1a6854060d5d3ada16c580a29f8c5ce21f3367f8/upgrade.properties

@@ -0,0 +1,3 @@
+description: Support expanded compilation argument lists
+compatibility: full
+compilation_expanded_args.rel: delete

cpp/ql/lib/change-notes/2025-11-13-expanded.md

@@ -0,0 +1,4 @@
+---
+category: feature
+---
+* New predicates `getAnExpandedArgument` and `getExpandedArgument` were added to the `Compilation` class, yielding compilation arguments after expansion of response files.

cpp/ql/lib/semmle/code/cpp/Compilation.qll

@@ -94,6 +94,21 @@ class Compilation extends @compilation {
    */
   string getArgument(int i) { compilation_args(this, i, result) }
 
+  /**
+   * Gets an expanded argument passed to the extractor on this invocation.
+   */
+  string getAnExpandedArgument() { result = this.getArgument(_) }
+
+  /**
+   * Gets the `i`th expanded argument passed to the extractor on this
+   * invocation.
+   *
+   * This is similar to `getArgument`, but for a `@someFile` argument, it
+   * includes the arguments from that file, rather than just taking the
+   * argument literally.
+   */
+  string getExpandedArgument(int i) { compilation_expanded_args(this, i, result) }
+
   /**
    * Gets the total amount of CPU time spent processing all the files in the
    * front-end and extractor.

cpp/ql/lib/semmlecode.cpp.dbscheme

@@ -47,6 +47,19 @@ compilation_args(
     string arg : string ref
 );
 
+/**
+ * The expanded arguments that were passed to the extractor for a
+ * compiler invocation. This is similar to `compilation_args`, but
+ * for a `@someFile` argument, it includes the arguments from that
+ * file, rather than just taking the argument literally.
+ */
+#keyset[id, num]
+compilation_expanded_args(
+    int id : @compilation ref,
+    int num : int ref,
+    string arg : string ref
+);
+
 /**
  * Optionally, record the build mode for each compilation.
  */