Relocate macro_backtrace to macro and remove macro_backtrace

tests/ui/README.md

@@ -891,12 +891,6 @@ Exercise *Link-Time Optimization* (LTO), involving the flags `-C lto` or `-Z thi
 
 Tests on changes to inference variable lattice LUB/GLB, see <https://github.com/rust-lang/rust/pull/45853>.
 
-## `tests/ui/macro_backtrace/`: `-Zmacro-backtrace`
-
-Contains a single test, checking the unstable command-line flag to enable detailed macro backtraces.
-
-**FIXME**: This could be merged with `ui/macros`, which already contains other macro backtrace tests.
-
 ## `tests/ui/macros/`
 
 Broad category of tests on macros.

tests/ui/macros/auxiliary/ping.rs

@@ -1,30 +1,30 @@
-// Test that the macro backtrace facility works (supporting file)
+// Test that the macro backtrace facility works (supporting macro-backtrace-complex.rs)
 
 // a non-local macro
 #[macro_export]
 macro_rules! ping {
     () => {
         pong!();
-    }
+    };
 }
 
 #[macro_export]
 macro_rules! deep {
     () => {
         foo!();
-    }
+    };
 }
 
 #[macro_export]
 macro_rules! foo {
     () => {
         bar!();
-    }
+    };
 }
 
 #[macro_export]
 macro_rules! bar {
     () => {
         ping!();
-    }
+    };
 }

tests/ui/macros/macro-backtrace-complex.-Zmacro-backtrace.stderr

@@ -1,5 +1,5 @@
 error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
-  --> $DIR/main.rs:10:20
+  --> $DIR/macro-backtrace-complex.rs:12:20
    |
 LL | / macro_rules! pong {
 LL | |     () => { syntax error };
@@ -11,7 +11,7 @@ LL |       pong!();
    |       ------- in this macro invocation
 
 error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
-  --> $DIR/main.rs:10:20
+  --> $DIR/macro-backtrace-complex.rs:12:20
    |
 LL | / macro_rules! pong {
 LL | |     () => { syntax error };
@@ -31,7 +31,7 @@ LL |           pong!();
    |           ------- in this macro invocation (#2)
 
 error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
-  --> $DIR/main.rs:10:20
+  --> $DIR/macro-backtrace-complex.rs:12:20
    |
 LL | / macro_rules! pong {
 LL | |     () => { syntax error };

tests/ui/macros/macro-backtrace-complex.default.stderr

@@ -1,5 +1,5 @@
 error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
-  --> $DIR/main.rs:10:20
+  --> $DIR/macro-backtrace-complex.rs:12:20
    |
 LL |     () => { syntax error };
    |                    ^^^^^ expected one of 8 possible tokens
@@ -10,7 +10,7 @@ LL |     pong!();
    = note: this error originates in the macro `pong` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
-  --> $DIR/main.rs:10:20
+  --> $DIR/macro-backtrace-complex.rs:12:20
    |
 LL |     () => { syntax error };
    |                    ^^^^^ expected one of 8 possible tokens
@@ -21,7 +21,7 @@ LL |     ping!();
    = note: this error originates in the macro `pong` which comes from the expansion of the macro `ping` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
-  --> $DIR/main.rs:10:20
+  --> $DIR/macro-backtrace-complex.rs:12:20
    |
 LL |     () => { syntax error };
    |                    ^^^^^ expected one of 8 possible tokens

tests/ui/macros/macro-backtrace-complex.rs

@@ -1,9 +1,11 @@
-// Test that the macro backtrace facility works
+// Test the unstable command-line flag (-Z macro-backtrace) to enable detailed macro backtraces
+// across nested local and external macros.
 //@ aux-build:ping.rs
 //@ revisions: default -Zmacro-backtrace
 //@[-Zmacro-backtrace] compile-flags: -Z macro-backtrace
 
-#[macro_use] extern crate ping;
+#[macro_use]
+extern crate ping;
 
 // a local macro
 macro_rules! pong {