coverage: Simplify access to debug/testing -Zcoverage-options flags

Author: Zalathar

compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/covfun.rs

@@ -131,7 +131,7 @@ fn fill_region_tables<'tcx>(
     // codegen needs to handle that gracefully to avoid #133606.
     // It's hard for tests to trigger this organically, so instead we set
     // `-Zcoverage-options=discard-all-spans-in-codegen` to force it to occur.
-    let discard_all = tcx.sess.coverage_discard_all_spans_in_codegen();
+    let discard_all = tcx.sess.coverage_options().discard_all_spans_in_codegen;
     let make_coords = |span: Span| {
         if discard_all { None } else { spans::make_coords(source_map, &source_file, span) }
     };

compiler/rustc_session/src/config.rs

@@ -182,6 +182,7 @@ pub enum InstrumentCoverage {
 pub struct CoverageOptions {
     pub level: CoverageLevel,
 
+    /// **(internal test-only flag)**
     /// `-Zcoverage-options=discard-all-spans-in-codegen`: During codegen,
     /// discard all coverage spans as though they were invalid. Needed by
     /// regression tests for #133606, because we don't have an easy way to

compiler/rustc_session/src/session.rs

@@ -39,8 +39,8 @@ use rustc_target::spec::{
 use crate::code_stats::CodeStats;
 pub use crate::code_stats::{DataTypeKind, FieldInfo, FieldKind, SizeKind, VariantInfo};
 use crate::config::{
-    self, CoverageLevel, CrateType, DebugInfo, ErrorOutputType, FunctionReturn, Input,
-    InstrumentCoverage, OptLevel, OutFileName, OutputType, RemapPathScopeComponents,
+    self, CoverageLevel, CoverageOptions, CrateType, DebugInfo, ErrorOutputType, FunctionReturn,
+    Input, InstrumentCoverage, OptLevel, OutFileName, OutputType, RemapPathScopeComponents,
     SwitchWithOptPath,
 };
 use crate::filesearch::FileSearch;
@@ -359,9 +359,11 @@ impl Session {
             && self.opts.unstable_opts.coverage_options.level >= CoverageLevel::Mcdc
     }
 
-    /// True if `-Zcoverage-options=discard-all-spans-in-codegen` was passed.
-    pub fn coverage_discard_all_spans_in_codegen(&self) -> bool {
-        self.opts.unstable_opts.coverage_options.discard_all_spans_in_codegen
+    /// Provides direct access to the `CoverageOptions` struct, so that
+    /// individual flags for debugging/testing coverage instrumetation don't
+    /// need separate accessors.
+    pub fn coverage_options(&self) -> &CoverageOptions {
+        &self.opts.unstable_opts.coverage_options
     }
 
     pub fn is_sanitizer_cfi_enabled(&self) -> bool {