Rollup merge of rust-lang#143752 - pmur:murp/no-panic-detect-wasi-cc, r=Kobzol

Don't panic if WASI_SDK_PATH not set when detecting compiler

The fedora packaging builds the wasm sysroot outside of the rust build system. Fedora applies a couple of patches related to wasm which I think make this possible. Not panicking seems consistent with the detection logic of other targets when they cannot find cc.

Author: jhpratt

src/bootstrap/src/utils/cc_detect.rs

@@ -220,10 +220,15 @@ fn default_compiler(
         }
 
         t if t.contains("-wasi") => {
-            let root = build
-                .wasi_sdk_path
-                .as_ref()
-                .expect("WASI_SDK_PATH mut be configured for a -wasi target");
+            let root = if let Some(path) = build.wasi_sdk_path.as_ref() {
+                path
+            } else {
+                if build.config.is_running_on_ci {
+                    panic!("ERROR: WASI_SDK_PATH must be configured for a -wasi target on CI");
+                }
+                println!("WARNING: WASI_SDK_PATH not set, using default cc/cxx compiler");
+                return None;
+            };
             let compiler = match compiler {
                 Language::C => format!("{t}-clang"),
                 Language::CPlusPlus => format!("{t}-clang++"),