Fuel is incompatible with incremental compilation

Author: tmiasko

compiler/rustc_session/src/config.rs

@@ -2640,9 +2640,13 @@ pub fn build_session_options(
         handler.early_error("value for threads must be a positive non-zero integer");
     }
 
-    if unstable_opts.threads > 1 && unstable_opts.fuel.is_some() {
+    let fuel = unstable_opts.fuel.is_some() || unstable_opts.print_fuel.is_some();
+    if fuel && unstable_opts.threads > 1 {
         handler.early_error("optimization fuel is incompatible with multiple threads");
     }
+    if fuel && cg.incremental.is_some() {
+        handler.early_error("optimization fuel is incompatible with incremental compilation");
+    }
 
     let incremental = cg.incremental.as_ref().map(PathBuf::from);
 

tests/ui/invalid-compile-flags/fuel.rs

@@ -0,0 +1,11 @@
+// revisions: incremental threads
+// dont-check-compiler-stderr
+//
+// [threads] compile-flags: -Zfuel=a=1 -Zthreads=2
+// [threads] error-pattern:optimization fuel is incompatible with multiple threads
+//
+// [incremental] incremental
+// [incremental] compile-flags: -Zprint-fuel=a
+// [incremental] error-pattern:optimization fuel is incompatible with incremental compilation
+
+fn main() {}