Handle gdb command failure gracefully in compiletest

Previously, if the gdb command was available, but threw an error, compiletest would panic.  This is obviously not good. Now, gdb is treated as missing if calling `gdb --version` does not output anything on stdout.

1 files changed, 6 insertions, 11 deletions

diff --git a/src/tools/compiletest/src/main.rs b/src/tools/compiletest/src/main.rs
index e3d453a991d..304143eaa0b 100644
--- a/src/tools/compiletest/src/main.rs
+++ b/src/tools/compiletest/src/main.rs
@@ -736,17 +736,12 @@ fn analyze_gdb(gdb: Option<String>) -> (Option<String>, Option<u32>, bool) {
         Some(ref s) => s,
     };
 
-    let version_line = Command::new(gdb)
-        .arg("--version")
-        .output()
-        .map(|output| {
-            String::from_utf8_lossy(&output.stdout)
-                .lines()
-                .next()
-                .unwrap()
-                .to_string()
-        })
-        .ok();
+    let mut version_line = None;
+    if let Ok(output) = Command::new(gdb).arg("--version").output() {
+        if let Some(first_line) = String::from_utf8_lossy(&output.stdout).lines().next() {
+            version_line = Some(first_line.to_string());
+        }
+    }
 
     let version = match version_line {
         Some(line) => extract_gdb_version(&line),