C++: Support C23/C++26 #embed preprocessor directives

Author: jketema

cpp/ql/lib/change-notes/2026-01-19-embed.md

@@ -0,0 +1,4 @@
+---
+category: feature
+---
+* Added a subclass `Embed` of `PreprocessorDirective` for C23 and C++26 `#embed` preprocessor directives.

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

@@ -328,3 +328,27 @@ class PreprocessorPragma extends PreprocessorDirective, @ppd_pragma {
 class PreprocessorLine extends PreprocessorDirective, @ppd_line {
   override string toString() { result = "#line " + this.getHead() }
 }
+
+/**
+ * A C23 or C++26`#embed` preprocessor directive. For example, the following code
+ * contains one `Embed` directive:
+ * ```cpp
+ * char arr[] = {
+ * #embed "bin"
+ * };
+ * ```
+ */
+class Embed extends PreprocessorDirective, @ppd_embed {
+  override string toString() { result = "#embed " + this.getIncludeText() }
+
+  /**
+   * Gets the token which occurs after `#embed`, for example `"filename"`
+   * or `<filename>`.
+   */
+  string getIncludeText() { result = this.getHead() }
+
+  /**
+   * Gets the file directly embedded by this `#embed`.
+   */
+  File getEmbeddedFile() { embeds(underlyingElement(this), unresolveElement(result)) }
+}

cpp/ql/lib/semmlecode.cpp.dbscheme

@@ -2353,6 +2353,7 @@ case @preprocdirect.kind of
 | 14 = @ppd_ms_import
 | 15 = @ppd_elifdef
 | 16 = @ppd_elifndef
+| 17 = @ppd_embed
 | 18 = @ppd_warning
 ;
 
@@ -2379,6 +2380,11 @@ includes(
     int included: @file ref
 );
 
+embeds(
+    unique int id: @ppd_embed ref,
+    int included: @file ref
+);
+
 link_targets(
     int id: @link_target,
     int binary: @file ref