cleanup FIXMEs

Author: DebugSteven

library/core/src/panic/panic_info.rs

@@ -66,7 +66,7 @@ impl<'a> PanicInfo<'a> {
     }
 
     #[unstable(feature = "error_in_panic", issue = "none")]
-    /// FIXME
+    /// The lower-level source of this panic, if any.
     pub fn source(&self) -> Option<&(dyn Error + 'static)> {
         self.source
     }

library/core/src/panicking.rs

@@ -51,7 +51,22 @@ const _: () = assert!(cfg!(panic = "abort"), "panic_immediate_abort requires -C
 #[rustc_do_not_const_check] // hooked by const-eval
 #[rustc_const_unstable(feature = "core_panic", issue = "none")]
 pub const fn panic_fmt(fmt: fmt::Arguments<'_>) -> ! {
-    panic_source(fmt, None)
+    //panic_source(fmt, None)
+    if cfg!(feature = "panic_immediate_abort") {
+        super::intrinsics::abort()
+    }
+
+    // NOTE This function never crosses the FFI boundary; it's a Rust-to-Rust call
+    // that gets resolved to the `#[panic_handler]` function.
+    extern "Rust" {
+        #[lang = "panic_impl"]
+        fn panic_impl(pi: &PanicInfo<'_>) -> !;
+    }
+
+    let pi = PanicInfo::internal_constructor(Some(&fmt), Location::caller(), None, true);
+
+    // SAFETY: `panic_impl` is defined in safe Rust code and thus is safe to call.
+    unsafe { panic_impl(&pi) }
 }
 
 #[cold]
@@ -62,7 +77,7 @@ pub const fn panic_fmt(fmt: fmt::Arguments<'_>) -> ! {
 #[track_caller]
 #[rustc_do_not_const_check] // hooked by const-eval
 #[rustc_const_unstable(feature = "core_panic", issue = "none")]
-pub const fn panic_source(fmt: fmt::Arguments<'_>, source: Option<&(dyn Error + 'static)>) -> ! {
+pub const fn panic_source(fmt: fmt::Arguments<'_>, source: &(dyn Error + 'static)) -> ! {
     if cfg!(feature = "panic_immediate_abort") {
         super::intrinsics::abort()
     }
@@ -74,7 +89,7 @@ pub const fn panic_source(fmt: fmt::Arguments<'_>, source: Option<&(dyn Error +
         fn panic_impl(pi: &PanicInfo<'_>) -> !;
     }
 
-    let pi = PanicInfo::internal_constructor(Some(&fmt), Location::caller(), source, true);
+    let pi = PanicInfo::internal_constructor(Some(&fmt), Location::caller(), Some(source), true);
 
     // SAFETY: `panic_impl` is defined in safe Rust code and thus is safe to call.
     unsafe { panic_impl(&pi) }

src/test/ui/error-trait/error-in-panic.rs

@@ -44,10 +44,7 @@ impl error::Error for SourceError {
 }
 
 fn main() {
-    std::env::set_var("RUST_BACKTRACE", "full");
     let source_error = SourceError {};
     let source = MyErr {super_source: source_error};
-    //FIXME make the function do the Some wrapping for us
-    panic_source(format_args!("here's my panic error message"), Some(&source));
-
+    panic_source(format_args!("here's my panic error message"), &source);
 }

src/test/ui/error-trait/error-in-panic.run.stderr

@@ -1,25 +1,6 @@
-thread 'main' panicked at 'here's my panic error message', $DIR/error-in-panic.rs:51:5
+thread 'main' panicked at 'here's my panic error message', $DIR/error-in-panic.rs:49:5
 Source: my source error message
 
 Caused by:
       my source's source error message
-stack backtrace:
-   0:        0x10347e5cc - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h739002e9033ecbde
-   1:        0x1034c1ef4 - core::fmt::write::h7ee3c88f1a3812c3
-   2:        0x103467ad8 - std::io::Write::write_fmt::h46e675c7a43a1dc6
-   3:        0x10347e494 - std::sys_common::backtrace::print::h2db63c69899aa986
-   4:        0x103441588 - std::panicking::default_hook::{{closure}}::hbf1cbfed6089b966
-   5:        0x103441348 - std::panicking::default_hook::h394fc36f8066489c
-   6:        0x103441a3c - std::panicking::rust_panic_with_hook::h022616bb2ba4e178
-   7:        0x10344907c - std::panicking::begin_panic_handler::{{closure}}::h3128246bc073fcbe
-   8:        0x103448fdc - std::sys_common::backtrace::__rust_end_short_backtrace::hbb524939a68ed8b5
-   9:        0x103441660 - _rust_begin_unwind
-  10:        0x1034dd910 - core::panicking::panic_source::hf14287b3ee2e7392
-  11:        0x102aeb728 - error_in_panic::main::hf4bbb2ae489ce4fd
-  12:        0x102aeb404 - core::ops::function::FnOnce::call_once::h0f54538c8c239b20
-  13:        0x102aeafd8 - std::sys_common::backtrace::__rust_begin_short_backtrace::h2b8f58dd23d62fa6
-  14:        0x102aeb074 - std::rt::lang_start::{{closure}}::h6d7fe7ddaa109f16
-  15:        0x10344478c - std::panicking::try::h0286e30fd7b2d786
-  16:        0x103452248 - std::rt::lang_start_internal::hc2ec5a7105141124
-  17:        0x102aeb048 - std::rt::lang_start::h8ea75b901d46518a
-  18:        0x102aeb7f0 - _main
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace