macros: Add test cases for recursive macro invocation

Author: CohenArthur

gcc/testsuite/rust/execute/torture/macros16.rs

@@ -0,0 +1,14 @@
+macro_rules! add {
+    ($e:literal) => {
+        0 + $e
+    };
+    ($e:literal $($es:literal)*) => {
+        $e + add!($($es)*)
+    };
+}
+
+fn main() -> i32 {
+    let a = add!(1 2 3 10); // 16
+
+    a - 16
+}

gcc/testsuite/rust/execute/torture/macros17.rs

@@ -0,0 +1,17 @@
+macro_rules! two {
+    (2) => {
+        3
+    };
+}
+
+macro_rules! one {
+    (1) => {
+        two!(2)
+    };
+}
+
+fn main() -> i32 {
+    let a = one!(1);
+
+    a - 3
+}

gcc/testsuite/rust/execute/torture/macros18.rs

@@ -0,0 +1,14 @@
+macro_rules! add {
+    ($e:literal) => {
+        0 + $e
+    };
+    ($e:literal $($es:literal)*) => {
+        $e + add!($($es)*)
+    };
+}
+
+fn main() -> i32 {
+    let a = add!(3 4); // 7
+
+    a - 7
+}