Rollup merge of #84734 - tmandry:compiletest-needs-unwind, r=Mark-Simulacrum

Add `needs-unwind` and beginning of support for testing `panic=abort` std to compiletest

For the Fuchsia platform we build libstd with `panic=abort` and would like a way to run tests with that enabled. This adds low-level support for this directly to compiletest.

In the future I'd like to add high-level support in rustbuild, e.g. having target-specific flags that allow configuring a panic strategy. (Side note: It would be nice if we could also build multiple configurations for the same target, but I'm getting ahead of myself.)

This plus #84500 have everything that's needed to get ui tests passing on fuchsia targets.

Part of #84766. Note that this change only includes the header on tests which need an unwinder to _build_, not those which need it to _run_.

r? ````@Mark-Simulacrum````

3 files changed, 30 insertions, 6 deletions

diff --git a/src/tools/compiletest/src/common.rs b/src/tools/compiletest/src/common.rs
index 2a14d8a3999..408c0b8da0b 100644
--- a/src/tools/compiletest/src/common.rs
+++ b/src/tools/compiletest/src/common.rs
@@ -171,6 +171,12 @@ impl fmt::Display for Debugger {
     }
 }
 
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum PanicStrategy {
+    Unwind,
+    Abort,
+}
+
 /// Configuration for compiletest
 #[derive(Debug, Clone)]
 pub struct Config {
@@ -265,6 +271,10 @@ pub struct Config {
     /// Flags to pass to the compiler when building for the target
     pub target_rustcflags: Option<String>,
 
+    /// What panic strategy the target is built with.  Unwind supports Abort, but
+    /// not vice versa.
+    pub target_panic: PanicStrategy,
+
     /// Target system to be tested
     pub target: String,
 
diff --git a/src/tools/compiletest/src/header.rs b/src/tools/compiletest/src/header.rs
index 56527420c0d..983934d129a 100644
--- a/src/tools/compiletest/src/header.rs
+++ b/src/tools/compiletest/src/header.rs
@@ -7,7 +7,7 @@ use std::path::{Path, PathBuf};
 
 use tracing::*;
 
-use crate::common::{CompareMode, Config, Debugger, FailMode, Mode, PassMode};
+use crate::common::{CompareMode, Config, Debugger, FailMode, Mode, PanicStrategy, PassMode};
 use crate::util;
 use crate::{extract_cdb_version, extract_gdb_version};
 
@@ -115,6 +115,12 @@ impl EarlyProps {
                     props.ignore = true;
                 }
 
+                if config.target_panic == PanicStrategy::Abort
+                    && config.parse_name_directive(ln, "needs-unwind")
+                {
+                    props.ignore = true;
+                }
+
                 if config.target == "wasm32-unknown-unknown" && config.parse_check_run_results(ln) {
                     props.ignore = true;
                 }
diff --git a/src/tools/compiletest/src/main.rs b/src/tools/compiletest/src/main.rs
index f42f9fb237a..d53e19f2908 100644
--- a/src/tools/compiletest/src/main.rs
+++ b/src/tools/compiletest/src/main.rs
@@ -5,7 +5,9 @@
 
 extern crate test;
 
-use crate::common::{expected_output_path, output_base_dir, output_relative_path, UI_EXTENSIONS};
+use crate::common::{
+    expected_output_path, output_base_dir, output_relative_path, PanicStrategy, UI_EXTENSIONS,
+};
 use crate::common::{CompareMode, Config, Debugger, Mode, PassMode, Pretty, TestPaths};
 use crate::util::logv;
 use getopts::Options;
@@ -97,8 +99,9 @@ pub fn parse_config(args: Vec<String>) -> Config {
              (eg. emulator, valgrind)",
             "PROGRAM",
         )
-        .optopt("", "host-rustcflags", "flags to pass to rustc for host", "FLAGS")
-        .optopt("", "target-rustcflags", "flags to pass to rustc for target", "FLAGS")
+        .optmulti("", "host-rustcflags", "flags to pass to rustc for host", "FLAGS")
+        .optmulti("", "target-rustcflags", "flags to pass to rustc for target", "FLAGS")
+        .optopt("", "target-panic", "what panic strategy the target supports", "unwind | abort")
         .optflag("", "verbose", "run tests verbosely, showing all output")
         .optflag(
             "",
@@ -243,8 +246,13 @@ pub fn parse_config(args: Vec<String>) -> Config {
         }),
         logfile: matches.opt_str("logfile").map(|s| PathBuf::from(&s)),
         runtool: matches.opt_str("runtool"),
-        host_rustcflags: matches.opt_str("host-rustcflags"),
-        target_rustcflags: matches.opt_str("target-rustcflags"),
+        host_rustcflags: Some(matches.opt_strs("host-rustcflags").join(" ")),
+        target_rustcflags: Some(matches.opt_strs("target-rustcflags").join(" ")),
+        target_panic: match matches.opt_str("target-panic").as_deref() {
+            Some("unwind") | None => PanicStrategy::Unwind,
+            Some("abort") => PanicStrategy::Abort,
+            _ => panic!("unknown `--target-panic` option `{}` given", mode),
+        },
         target,
         host: opt_str2(matches.opt_str("host")),
         cdb,