Rust: implement Expr::getType for cases where rust-analyzer does not provide one

Author: aibaars

rust/ql/.generated.list

@@ -1,4 +1,3 @@
-// generated by codegen, remove this comment if you wish to edit this file
 /**
  * This module provides a hand-modifiable wrapper around the generated class `BlockExpr`.
  *
@@ -12,6 +11,7 @@ private import codeql.rust.elements.internal.generated.BlockExpr
  * be referenced directly.
  */
 module Impl {
+  // the following QLdoc is generated: if you need to edit it, do it in the schema file
   /**
    * A block expression. For example:
    * ```rust
@@ -26,5 +26,16 @@ module Impl {
    * }
    * ```
    */
-  class BlockExpr extends Generated::BlockExpr { }
+  class BlockExpr extends Generated::BlockExpr {
+    override string getType() {
+      result = super.getType()
+      or
+      not exists(super.getType()) and
+      (
+        result = this.getStmtList().getTailExpr().getType()
+        or
+        not exists(this.getStmtList().getTailExpr()) and result = "()"
+      )
+    }
+  }
 }

rust/ql/.gitattributes

@@ -11,6 +11,7 @@ private import codeql.rust.elements.internal.generated.Synth
 private import codeql.rust.elements.Format
 private import codeql.rust.elements.NamedFormatArgument
 private import codeql.Locations
+private import codeql.rust.elements.Variable
 
 /**
  * INTERNAL: This module contains the customizable definition of `FormatTemplateVariableAccess` and should not
@@ -36,5 +37,9 @@ module Impl {
 
     /** Gets the underlying `NamedFormatArgument` . */
     NamedFormatArgument getArgument() { result = argument }
+
+    override string getType() {
+      result = any(Variable v | v.getAnAccess() = this).getPat().getType()
+    }
   }
 }

rust/ql/lib/codeql/rust/elements/internal/BlockExprImpl.qll

@@ -39,5 +39,13 @@ module Impl {
       or
       index = 3 and this.hasElse() and result = "else {...}"
     }
+
+    override string getType() {
+      result = super.getType()
+      or
+      // For some reason rust-analyzer does not return a type for a chained `if`, so we use the parent's type instead.
+      not exists(super.getType()) and
+      result = any(IfExpr parent | parent.getElse() = this).getType()
+    }
   }
 }

rust/ql/lib/codeql/rust/elements/internal/FormatTemplateVariableAccessImpl.qll

@@ -5,6 +5,8 @@
  */
 
 private import codeql.rust.elements.internal.generated.LiteralExpr
+private import codeql.rust.elements.FormatArgsExpr
+private import codeql.rust.elements.LiteralPat
 
 /**
  * INTERNAL: This module contains the customizable definition of `LiteralExpr` and should not
@@ -41,5 +43,13 @@ module Impl {
         if v.length() > 30 then result = v.substring(0, 30) + "..." else result = v
       )
     }
+
+    override string getType() {
+      result = super.getType()
+      or
+      exists(FormatArgsExpr f | f.getTemplate() = this and result = "&str")
+      or
+      result = any(LiteralPat p | p.getLiteral() = this).getType()
+    }
   }
 }

rust/ql/lib/codeql/rust/elements/internal/IfExprImpl.qll

@@ -1,22 +1,39 @@
-// generated by codegen, remove this comment if you wish to edit this file
 /**
  * This module provides a hand-modifiable wrapper around the generated class `MacroExpr`.
  *
  * INTERNAL: Do not use.
  */
 
 private import codeql.rust.elements.internal.generated.MacroExpr
+private import codeql.rust.elements.MacroStmts
 
 /**
  * INTERNAL: This module contains the customizable definition of `MacroExpr` and should not
  * be referenced directly.
  */
 module Impl {
+  // the following QLdoc is generated: if you need to edit it, do it in the schema file
   /**
    * A MacroExpr. For example:
    * ```rust
    * todo!()
    * ```
    */
-  class MacroExpr extends Generated::MacroExpr { }
+  class MacroExpr extends Generated::MacroExpr {
+    override string getType() {
+      result = super.getType()
+      or
+      not exists(super.getType()) and
+      (
+        result = this.getMacroCall().getExpanded().(Expr).getType() or
+        result = typeOf(this.getMacroCall().getExpanded().(MacroStmts))
+      )
+    }
+  }
+
+  string typeOf(MacroStmts stmts) {
+    result = stmts.getExpr().getType()
+    or
+    not exists(stmts.getExpr()) and result = "()"
+  }
 }

rust/ql/lib/codeql/rust/elements/internal/LiteralExprImpl.qll

@@ -5,6 +5,7 @@
  */
 
 private import codeql.rust.elements.internal.generated.PathExpr
+private import codeql.rust.elements.CallExpr
 
 /**
  * INTERNAL: This module contains the customizable definition of `PathExpr` and should not
@@ -25,5 +26,22 @@ module Impl {
     override string toString() { result = this.toAbbreviatedString() }
 
     override string toAbbreviatedString() { result = this.getPath().toString() }
+
+    override string getType() {
+      result = super.getType()
+      or
+      // Special case for `rustc_box`; these get translated to `box X` in the HIR layer.
+      // ```rust
+      // #[rustc_box]
+      // alloc.boxed::Box::new(X)
+      // ```
+      not exists(super.getType()) and
+      exists(CallExpr c, string tp |
+        c.getAnAttr().getMeta().getPath().getPart().getNameRef().getText() = "rustc_box" and
+        this = c.getExpr() and
+        tp = c.getArgList().getArg(0).getType() and
+        result = "fn new<T>(T) -> Box<T, Global>".replaceAll("T", tp)
+      )
+    }
   }
 }