Rollup merge of #144497 - Enselic:basic-stepping, r=Mark-Simulacrum

tests: Add test for basic line-by-line stepping in a debugger

Let's wait with lldb testing until the test works properly with gdb.

This is a regression test to prevent further regressions of https://github.com/rust-lang/rust/issues/33013 which unfortunately regressed in **nightly-2023-04-24**. See https://github.com/rust-lang/rust/issues/33013#issuecomment-3121579216.

tests/debuginfo/basic-stepping.rs

@@ -0,0 +1,47 @@
+//! Test that stepping through a simple program with a debugger one line at a
+//! time works intuitively, e.g. that `next` takes you to the next source line.
+//! Regression test for <https://github.com/rust-lang/rust/issues/33013>.
+
+//@ ignore-aarch64: Doesn't work yet.
+//@ compile-flags: -g
+
+// gdb-command: run
+// FIXME(#97083): Should we be able to break on initialization of zero-sized types?
+// FIXME(#97083): Right now the first breakable line is:
+// gdb-check:   let mut c = 27;
+// gdb-command: next
+// gdb-check:   let d = c = 99;
+// gdb-command: next
+// FIXME(#33013): gdb-check:   let e = "hi bob";
+// FIXME(#33013): gdb-command: next
+// FIXME(#33013): gdb-check:   let f = b"hi bob";
+// FIXME(#33013): gdb-command: next
+// FIXME(#33013): gdb-check:   let g = b'9';
+// FIXME(#33013): gdb-command: next
+// FIXME(#33013): gdb-check:   let h = ["whatever"; 8];
+// FIXME(#33013): gdb-command: next
+// gdb-check:   let i = [1,2,3,4];
+// gdb-command: next
+// gdb-check:   let j = (23, "hi");
+// gdb-command: next
+// gdb-check:   let k = 2..3;
+// gdb-command: next
+// gdb-check:   let l = &i[k];
+// gdb-command: next
+// gdb-check:   let m: *const() = &a;
+
+fn main () {
+    let a = (); // #break
+    let b : [i32; 0] = [];
+    let mut c = 27;
+    let d = c = 99;
+    let e = "hi bob";
+    let f = b"hi bob";
+    let g = b'9';
+    let h = ["whatever"; 8];
+    let i = [1,2,3,4];
+    let j = (23, "hi");
+    let k = 2..3;
+    let l = &i[k];
+    let m: *const() = &a;
+}