The value of -Cinstrument-coverage= doesn't need to be Option

Not using this flag is identical to passing `-Cinstrument-coverage=off`, so
there's no need to distinguish between `None` and `Some(Off)`.

Author: Zalathar

compiler/rustc_interface/src/tests.rs

@@ -612,7 +612,7 @@ fn test_codegen_options_tracking_hash() {
     tracked!(force_frame_pointers, Some(false));
     tracked!(force_unwind_tables, Some(true));
     tracked!(inline_threshold, Some(0xf007ba11));
-    tracked!(instrument_coverage, Some(InstrumentCoverage::All));
+    tracked!(instrument_coverage, InstrumentCoverage::All);
     tracked!(link_dead_code, Some(true));
     tracked!(linker_plugin_lto, LinkerPluginLto::LinkerPluginAuto);
     tracked!(llvm_args, vec![String::from("1"), String::from("2")]);

compiler/rustc_session/src/config.rs

@@ -2743,13 +2743,11 @@ pub fn build_session_options(
     // This is what prevents them from being used on stable compilers.
     match cg.instrument_coverage {
         // Stable values:
-        Some(InstrumentCoverage::All | InstrumentCoverage::Off) | None => {}
+        InstrumentCoverage::All | InstrumentCoverage::Off => {}
         // Unstable values:
-        Some(
-            InstrumentCoverage::Branch
-            | InstrumentCoverage::ExceptUnusedFunctions
-            | InstrumentCoverage::ExceptUnusedGenerics,
-        ) => {
+        InstrumentCoverage::Branch
+        | InstrumentCoverage::ExceptUnusedFunctions
+        | InstrumentCoverage::ExceptUnusedGenerics => {
             if !unstable_opts.unstable_options {
                 handler.early_error(
                     "`-C instrument-coverage=branch` and `-C instrument-coverage=except-*` \
@@ -2759,7 +2757,7 @@ pub fn build_session_options(
         }
     }
 
-    if cg.instrument_coverage.is_some() && cg.instrument_coverage != Some(InstrumentCoverage::Off) {
+    if cg.instrument_coverage != InstrumentCoverage::Off {
         if cg.profile_generate.enabled() || cg.profile_use.is_some() {
             handler.early_error(
                 "option `-C instrument-coverage` is not compatible with either `-C profile-use` \

compiler/rustc_session/src/options.rs

@@ -294,7 +294,7 @@ impl CodegenOptions {
     // JUSTIFICATION: defn of the suggested wrapper fn
     #[allow(rustc::bad_opt_access)]
     pub fn instrument_coverage(&self) -> InstrumentCoverage {
-        self.instrument_coverage.unwrap_or(InstrumentCoverage::Off)
+        self.instrument_coverage
     }
 }
 
@@ -913,23 +913,23 @@ mod parse {
     }
 
     pub(crate) fn parse_instrument_coverage(
-        slot: &mut Option<InstrumentCoverage>,
+        slot: &mut InstrumentCoverage,
         v: Option<&str>,
     ) -> bool {
         if v.is_some() {
-            let mut bool_arg = None;
-            if parse_opt_bool(&mut bool_arg, v) {
-                *slot = bool_arg.unwrap().then_some(InstrumentCoverage::All);
+            let mut bool_arg = false;
+            if parse_bool(&mut bool_arg, v) {
+                *slot = if bool_arg { InstrumentCoverage::All } else { InstrumentCoverage::Off };
                 return true;
             }
         }
 
         let Some(v) = v else {
-            *slot = Some(InstrumentCoverage::All);
+            *slot = InstrumentCoverage::All;
             return true;
         };
 
-        *slot = Some(match v {
+        *slot = match v {
             "all" => InstrumentCoverage::All,
             "branch" => InstrumentCoverage::Branch,
             "except-unused-generics" | "except_unused_generics" => {
@@ -940,7 +940,7 @@ mod parse {
             }
             "off" | "no" | "n" | "false" | "0" => InstrumentCoverage::Off,
             _ => return false,
-        });
+        };
         true
     }
 
@@ -1352,7 +1352,7 @@ options! {
     inline_threshold: Option<u32> = (None, parse_opt_number, [TRACKED],
         "set the threshold for inlining a function"),
     #[rustc_lint_opt_deny_field_access("use `Session::instrument_coverage` instead of this field")]
-    instrument_coverage: Option<InstrumentCoverage> = (None, parse_instrument_coverage, [TRACKED],
+    instrument_coverage: InstrumentCoverage = (InstrumentCoverage::Off, parse_instrument_coverage, [TRACKED],
         "instrument the generated code to support LLVM source-based code coverage \
         reports (note, the compiler build config must include `profiler = true`); \
         implies `-C symbol-mangling-version=v0`. Optional values are: