Merge pull request #7928 from jketema/structured-bindings-db-scheme

C++: Add table that identifies C++ structured bindings

cpp/downgrades/bb0f279f2acd793105a347d589b5afc8715d94c4/upgrade.properties

@@ -0,0 +1,3 @@
+description: Add relation for tracking variables from structured binding declarations
+compatibility: full
+is_structured_binding.rel: delete

cpp/ql/lib/change-notes/2022-02-21-structured-binding-data.md

@@ -0,0 +1,4 @@
+---
+category: feature
+---
+* Added a `isStructuredBinding` predicate to the `Variable` class which holds when the variable is declared as part of a structured binding declaration.

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

@@ -169,6 +169,12 @@ class Variable extends Declaration, @variable {
     variable_instantiation(underlyingElement(this), unresolveElement(v))
   }
 
+  /**
+   * Holds if this variable is declated as part of a structured binding
+   * declaration. For example, `x` in `auto [x, y] = ...`.
+   */
+  predicate isStructuredBinding() { is_structured_binding(underlyingElement(this)) }
+
   /**
    * Holds if this is a compiler-generated variable. For example, a
    * [range-based for loop](http://en.cppreference.com/w/cpp/language/range-for)

cpp/ql/lib/semmlecode.cpp.dbscheme

@@ -446,6 +446,7 @@ var_decl_specifiers(
     int id: @var_decl ref,
     string name: string ref
 )
+is_structured_binding(unique int id: @variable ref);
 
 type_decls(
     unique int id: @type_decl,

cpp/ql/lib/semmlecode.cpp.dbscheme.stats

@@ -14877,6 +14877,17 @@
 </dependencies>
 </relation>
 <relation>
+<name>is_structured_binding</name>
+<cardinality>10</cardinality>
+<columnsizes>
+<e>
+<k>id</k>
+<v>10</v>
+</e>
+</columnsizes>
+<dependencies/>
+</relation>
+<relation>
 <name>type_decls</name>
 <cardinality>1316547</cardinality>
 <columnsizes>

cpp/ql/lib/upgrades/2cd420191e5f782589b4e4efb70127de265390dd/upgrade.properties

@@ -0,0 +1,2 @@
+description: Add relation for tracking variables from structured binding declarations
+compatibility: backwards