From 75bf1aa6007cfd8ec1fc0ddffcec2718dc522301 Mon Sep 17 00:00:00 2001
From: Andrew Teylu <andrew.teylu@vector.com>
Date: Thu, 10 Sep 2026 19:02:06 +0100
Subject: [PATCH] Avoid oscillating line wrapping due to symbol indices

A comment against PR 151817 mentioned that the test file added in this
PR kept causing "arbitrary" test file changes.

This is because one line of the expanded output sits *just* at 78
columns, which is the pretty-printer's margin. Adding or removing a
symbol shifts every index after it, and when one of those gains or loses
a digit, the wrapping moves.

We cannot use `normalize-stdout` as the layout is decided before
normalization runs.

We fix this by avoiding a strict golden comparison, and instead using a
regex to directly test that the expected syntax contexts exist in the
expanded output.
---
 tests/ui/hygiene/unpretty-debug-lifetimes.rs  | 11 +++++--
 .../hygiene/unpretty-debug-lifetimes.stdout   | 33 -------------------
 2 files changed, 9 insertions(+), 35 deletions(-)
 delete mode 100644 tests/ui/hygiene/unpretty-debug-lifetimes.stdout

diff --git a/tests/ui/hygiene/unpretty-debug-lifetimes.rs b/tests/ui/hygiene/unpretty-debug-lifetimes.rs
index ee8be21b60d01..5f8a20281ab04 100644
--- a/tests/ui/hygiene/unpretty-debug-lifetimes.rs
+++ b/tests/ui/hygiene/unpretty-debug-lifetimes.rs
@@ -4,8 +4,15 @@
 // Regression test for lifetime hygiene annotations in -Zunpretty=expanded,hygiene
 // Previously, lifetimes were missing the #N syntax context suffix.
 
-// Don't break whenever Symbol numbering changes
-//@ normalize-stdout: "\d+#" -> "0#"
+// This test deliberately has no `.stdout` snapshot. The hygiene annotations
+// embed `Symbol` indices, whose width feeds into the pretty-printer's line
+// breaking, so the layout shifts whenever a `Symbol` gains or loses a digit.
+// `normalize-stdout` can't help, because the layout is decided before
+// normalization runs. Assert the property this test is about instead: the two
+// `'a` share their text but carry different syntax contexts.
+//@ dont-check-compiler-stdout
+//@ check-stdout
+//@ regex-error-pattern: f\s*/\*\s*\d+#0\s*\*/<'a\s*/\*\s*\d+#0\s*\*/,\s*'a\s*/\*\s*\d+#1\s*\*/
 
 #![feature(decl_macro)]
 #![feature(no_core)]
diff --git a/tests/ui/hygiene/unpretty-debug-lifetimes.stdout b/tests/ui/hygiene/unpretty-debug-lifetimes.stdout
deleted file mode 100644
index 689453326c0b5..0000000000000
--- a/tests/ui/hygiene/unpretty-debug-lifetimes.stdout
+++ /dev/null
@@ -1,33 +0,0 @@
-//@ check-pass
-//@ compile-flags: -Zunpretty=expanded,hygiene
-
-// Regression test for lifetime hygiene annotations in -Zunpretty=expanded,hygiene
-// Previously, lifetimes were missing the #N syntax context suffix.
-
-// Don't break whenever Symbol numbering changes
-//@ normalize-stdout: "\d+#" -> "0#"
-
-#![feature /* 0#0 */(decl_macro /* 0#0 */)]
-#![feature /* 0#0 */(no_core /* 0#0 */)]
-#![no_core /* 0#0 */]
-
-macro lifetime_hygiene
-    /*
-    0#0
-    */ {
-    ($f /* 0#0 */:ident /* 0#0 */<$a /* 0#0 */:lifetime /* 0#0 */>)
-    =>
-    { fn /* 0#0 */ $f /* 0#0 */<$a /* 0#0 */, 'a /* 0#0 */>() {} }
-}
-fn f /* 0#0 */<'a /* 0#0 */, 'a /* 0#1 */>() {}
-
-
-/*
-Expansions:
-crate0::{{expn0}}: parent: crate0::{{expn0}}, call_site_ctxt: #0, def_site_ctxt: #0, kind: Root
-crate0::{{expn1}}: parent: crate0::{{expn0}}, call_site_ctxt: #0, def_site_ctxt: #0, kind: Macro(Bang, "lifetime_hygiene")
-
-SyntaxContexts:
-#0: parent: #0, outer_mark: (crate0::{{expn0}}, Opaque)
-#1: parent: #0, outer_mark: (crate0::{{expn1}}, Opaque)
-*/