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[rust2cpg] handle empty macro call expansions. #6226

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Merged
xavierpinho merged 1 commit into from
Aug 26, 2026
Merged

[rust2cpg] handle empty macro call expansions. #6226

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3 changes: 2 additions & 1 deletion joern-cli/frontends/rust2cpg/src/main/scala/io/joern/rust2cpg/astcreation/RustVisitor.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1644,8 +1644,9 @@ trait RustVisitor(implicit withSchemaValidation: ValidationMode) { this: AstCrea
// MacroCall
private def visitMacroExpr(macroExpr: MacroExpr): Ast = {
visitMacroCall(macroExpr.macroCall) match {
case Nil => macroNotExpanded(macroExpr.macroCall)
case exprAst :: Nil => exprAst
case asts => blockAst(blockNode(macroExpr), asts.toList)
case asts => blockAst(blockNode(macroExpr, code(macroExpr), typeFullNameForExpr(macroExpr)), asts.toList)
}
}

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56 changes: 56 additions & 0 deletions joern-cli/frontends/rust2cpg/src/test/scala/io/joern/rust2cpg/passes/ast/MacroTests.scala
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Expand Up @@ -126,6 +126,8 @@ class MacroTests extends Rust2CpgSuite(noSysRoot = true) {

"have correct children" in {
inside(cpg.method.nameExact("main").block.assignment.source.isBlock.astChildren.l) { case (three: Block) :: Nil =>
three.code shouldBe "three!()"
three.typeFullName shouldBe "i32"
inside(three.astChildren.l) {
case (local: Local) :: (assign: Call) :: (assignPlus: Call) :: (ident: Identifier) :: Nil =>
local.name shouldBe "s"
Expand Down Expand Up @@ -196,6 +198,60 @@ class MacroTests extends Rust2CpgSuite(noSysRoot = true) {
}
}
}

"identity proc-macro call" should {
val cpg = code("""
|use proc_macro::TokenStream;
|
|#[proc_macro]
|pub fn foo(item: TokenStream) -> TokenStream { item }
|
|pub fn bar() {
| let baz = foo![Qux];
| foo![Qux]
|}
|""".stripMargin)
.moreCode(
"""
|[package]
|name = "rust2cpgtest"
|version = "0.1.0"
|edition = "2021"
|
|[lib]
|proc-macro = true
|""".stripMargin,
fileName = "Cargo.toml"
)

"have correct assignment" in {
cpg.method.fullNameExact("rust2cpgtest::bar").block.assignment.code.l shouldBe List("let baz = foo![Qux];")

// TODO(rust_ast_gen): expand proc-macros.
inside(cpg.method.fullNameExact("rust2cpgtest::bar").block.assignment.source.l) { case (qux: Unknown) :: Nil =>
qux.code shouldBe "foo![Qux]"
qux.lineNumber shouldBe Some(8)
}
pendingUntilFixed {
inside(cpg.method.fullNameExact("rust2cpgtest::bar").block.assignment.source.l) {
case (qux: Identifier) :: Nil =>
qux.name shouldBe "Qux"
qux.code shouldBe "Qux"
}
}
}

// TODO: update once proc-macros are supported.
"have correct return" in {
inside(cpg.method.nameExact("bar").block.astChildren.isReturn.l) { case ret :: Nil =>
ret.code shouldBe "foo![Qux]"
inside(ret.astChildren.l) { case (qux: Unknown) :: Nil =>
qux.code shouldBe "foo![Qux]"
qux.lineNumber shouldBe Some(9)
}
}
}
}
}

class MacroTestsWithSysroot extends Rust2CpgSuite(noSysRoot = false) {
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