Replace uses of `parse_opt_*` with `parse_*` where possible.

This lets us specify the default at the options declaration point,
instead of using `.unwrap(default)` or `None | Some(default)` at some
use point far away. It also makes the code more concise.

src/librustc_codegen_llvm/back/write.rs

@@ -347,7 +347,7 @@ pub(crate) fn should_use_new_llvm_pass_manager(config: &ModuleConfig) -> bool {
     }
 
     // The new pass manager is disabled by default.
-    config.new_llvm_pass_manager.unwrap_or(false)
+    config.new_llvm_pass_manager
 }
 
 pub(crate) unsafe fn optimize_with_new_llvm_pass_manager(

src/librustc_codegen_ssa/back/link.rs

@@ -858,18 +858,7 @@ fn preserve_objects_for_their_debuginfo(sess: &Session) -> bool {
     // *not* running dsymutil then the object files are the only source of truth
     // for debug information, so we must preserve them.
     if sess.target.target.options.is_like_osx {
-        match sess.opts.debugging_opts.run_dsymutil {
-            // dsymutil is not being run, preserve objects
-            Some(false) => return true,
-
-            // dsymutil is being run, no need to preserve the objects
-            Some(true) => return false,
-
-            // The default historical behavior was to always run dsymutil, so
-            // we're preserving that temporarily, but we're likely to switch the
-            // default soon.
-            None => return false,
-        }
+        return !sess.opts.debugging_opts.run_dsymutil;
     }
 
     false
@@ -1324,11 +1313,11 @@ fn link_local_crate_native_libs_and_dependent_crate_libs<'a, B: ArchiveBuilder<'
     // If -Zlink-native-libraries=false is set, then the assumption is that an
     // external build system already has the native dependencies defined, and it
     // will provide them to the linker itself.
-    if sess.opts.debugging_opts.link_native_libraries.unwrap_or(true) {
+    if sess.opts.debugging_opts.link_native_libraries {
         add_local_native_libraries(cmd, sess, codegen_results);
     }
     add_upstream_rust_crates::<B>(cmd, sess, codegen_results, crate_type, tmpdir);
-    if sess.opts.debugging_opts.link_native_libraries.unwrap_or(true) {
+    if sess.opts.debugging_opts.link_native_libraries {
         add_upstream_native_libraries(cmd, sess, codegen_results, crate_type);
     }
 }
@@ -1534,9 +1523,7 @@ fn linker_with_args<'a, B: ArchiveBuilder<'a>>(
     // OBJECT-FILES-NO, AUDIT-ORDER
     // We want to prevent the compiler from accidentally leaking in any system libraries,
     // so by default we tell linkers not to link to any default libraries.
-    if !sess.opts.cg.default_linker_libraries.unwrap_or(false)
-        && sess.target.target.options.no_default_libraries
-    {
+    if !sess.opts.cg.default_linker_libraries && sess.target.target.options.no_default_libraries {
         cmd.no_default_libraries();
     }
 

src/librustc_codegen_ssa/back/linker.rs

@@ -384,7 +384,7 @@ fn debuginfo(&mut self) {
             // If we are building without debuginfo enabled and we were called with
             // `-Zstrip-debuginfo-if-disabled=yes`, tell the linker to strip any debuginfo
             // found when linking to get rid of symbols from libstd.
-            if let Some(true) = self.sess.opts.debugging_opts.strip_debuginfo_if_disabled {
+            if self.sess.opts.debugging_opts.strip_debuginfo_if_disabled {
                 self.linker_arg("-S");
             }
         };

src/librustc_codegen_ssa/back/write.rs

@@ -115,7 +115,7 @@ pub struct ModuleConfig {
     pub vectorize_slp: bool,
     pub merge_functions: bool,
     pub inline_threshold: Option<usize>,
-    pub new_llvm_pass_manager: Option<bool>,
+    pub new_llvm_pass_manager: bool,
 }
 
 impl ModuleConfig {

src/librustc_interface/tests.rs

@@ -375,7 +375,7 @@ fn test_codegen_options_tracking_hash() {
     let mut opts = Options::default();
 
     // Make sure the changing an [UNTRACKED] option leaves the hash unchanged
-    opts.cg.ar = Some(String::from("abc"));
+    opts.cg.ar = String::from("abc");
     assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
 
     opts.cg.linker = Some(PathBuf::from("linker"));
@@ -479,11 +479,11 @@ fn test_codegen_options_tracking_hash() {
     assert!(reference.dep_tracking_hash() != opts.dep_tracking_hash());
 
     opts = reference.clone();
-    opts.cg.debuginfo = Some(0xdeadbeef);
+    opts.cg.debuginfo = 0xdeadbeef;
     assert!(reference.dep_tracking_hash() != opts.dep_tracking_hash());
 
     opts = reference.clone();
-    opts.cg.debuginfo = Some(0xba5eba11);
+    opts.cg.debuginfo = 0xba5eba11;
     assert!(reference.dep_tracking_hash() != opts.dep_tracking_hash());
 
     opts = reference.clone();

src/librustc_middle/ty/layout.rs

@@ -2182,9 +2182,7 @@ fn pointee_info_at(this: TyAndLayout<'tcx>, cx: &C, offset: Size) -> Option<Poin
                         //
                         // For now, do not enable mutable_noalias by default at all, while the
                         // issue is being figured out.
-                        let mutable_noalias =
-                            tcx.sess.opts.debugging_opts.mutable_noalias.unwrap_or(false);
-                        if mutable_noalias {
+                        if tcx.sess.opts.debugging_opts.mutable_noalias {
                             PointerKind::UniqueBorrowed
                         } else {
                             PointerKind::Shared

src/librustc_session/config.rs

@@ -617,10 +617,6 @@ pub fn share_generics(&self) -> bool {
 }
 
 impl DebuggingOptions {
-    pub fn ui_testing(&self) -> bool {
-        self.ui_testing.unwrap_or(false)
-    }
-
     pub fn diagnostic_handler_flags(&self, can_emit_warnings: bool) -> HandlerFlags {
         HandlerFlags {
             can_emit_warnings,
@@ -628,7 +624,7 @@ pub fn diagnostic_handler_flags(&self, can_emit_warnings: bool) -> HandlerFlags
             dont_buffer_diagnostics: self.dont_buffer_diagnostics,
             report_delayed_bugs: self.report_delayed_bugs,
             macro_backtrace: self.macro_backtrace,
-            deduplicate_diagnostics: self.deduplicate_diagnostics.unwrap_or(true),
+            deduplicate_diagnostics: self.deduplicate_diagnostics,
         }
     }
 }
@@ -1395,15 +1391,14 @@ fn parse_opt_level(
     if max_o > max_c {
         OptLevel::Default
     } else {
-        match cg.opt_level.as_ref().map(String::as_ref) {
-            None => OptLevel::No,
-            Some("0") => OptLevel::No,
-            Some("1") => OptLevel::Less,
-            Some("2") => OptLevel::Default,
-            Some("3") => OptLevel::Aggressive,
-            Some("s") => OptLevel::Size,
-            Some("z") => OptLevel::SizeMin,
-            Some(arg) => {
+        match cg.opt_level.as_ref() {
+            "0" => OptLevel::No,
+            "1" => OptLevel::Less,
+            "2" => OptLevel::Default,
+            "3" => OptLevel::Aggressive,
+            "s" => OptLevel::Size,
+            "z" => OptLevel::SizeMin,
+            arg => {
                 early_error(
                     error_format,
                     &format!(
@@ -1436,10 +1431,10 @@ fn select_debuginfo(
         DebugInfo::Full
     } else {
         match cg.debuginfo {
-            None | Some(0) => DebugInfo::None,
-            Some(1) => DebugInfo::Limited,
-            Some(2) => DebugInfo::Full,
-            Some(arg) => {
+            0 => DebugInfo::None,
+            1 => DebugInfo::Limited,
+            2 => DebugInfo::Full,
+            arg => {
                 early_error(
                     error_format,
                     &format!(
@@ -1502,10 +1497,10 @@ fn parse_libs(
 }
 
 fn parse_borrowck_mode(dopts: &DebuggingOptions, error_format: ErrorOutputType) -> BorrowckMode {
-    match dopts.borrowck.as_ref().map(|s| &s[..]) {
-        None | Some("migrate") => BorrowckMode::Migrate,
-        Some("mir") => BorrowckMode::Mir,
-        Some(m) => early_error(error_format, &format!("unknown borrowck mode `{}`", m)),
+    match dopts.borrowck.as_ref() {
+        "migrate" => BorrowckMode::Migrate,
+        "mir" => BorrowckMode::Mir,
+        m => early_error(error_format, &format!("unknown borrowck mode `{}`", m)),
     }
 }
 

src/librustc_session/options.rs

@@ -613,7 +613,7 @@ fn parse_src_file_hash(slot: &mut Option<SourceFileHashAlgorithm>, v: Option<&st
 options! {CodegenOptions, CodegenSetter, basic_codegen_options,
           build_codegen_options, "C", "codegen",
           CG_OPTIONS, cg_type_desc, cgsetters,
-    ar: Option<String> = (None, parse_opt_string, [UNTRACKED],
+    ar: String = (String::new(), parse_string, [UNTRACKED],
         "this option is deprecated and does nothing"),
     linker: Option<PathBuf> = (None, parse_opt_pathbuf, [UNTRACKED],
         "system linker to link outputs with"),
@@ -666,10 +666,10 @@ fn parse_src_file_hash(slot: &mut Option<SourceFileHashAlgorithm>, v: Option<&st
         "print remarks for these optimization passes (space separated, or \"all\")"),
     no_stack_check: bool = (false, parse_bool, [UNTRACKED],
         "the `--no-stack-check` flag is deprecated and does nothing"),
-    debuginfo: Option<usize> = (None, parse_opt_uint, [TRACKED],
+    debuginfo: usize = (0, parse_uint, [TRACKED],
         "debug info emission level, 0 = no debug info, 1 = line tables only, \
          2 = full debug info with variable and type information"),
-    opt_level: Option<String> = (None, parse_opt_string, [TRACKED],
+    opt_level: String = ("0".to_string(), parse_string, [TRACKED],
         "optimize with possible levels 0-3, s, or z"),
     force_frame_pointers: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "force use of the frame pointers"),
@@ -681,7 +681,7 @@ fn parse_src_file_hash(slot: &mut Option<SourceFileHashAlgorithm>, v: Option<&st
         [TRACKED], "panic strategy to compile crate with"),
     incremental: Option<String> = (None, parse_opt_string, [UNTRACKED],
         "enable incremental compilation"),
-    default_linker_libraries: Option<bool> = (None, parse_opt_bool, [UNTRACKED],
+    default_linker_libraries: bool = (false, parse_bool, [UNTRACKED],
         "allow the linker to link its default libraries"),
     linker_flavor: Option<LinkerFlavor> = (None, parse_linker_flavor, [UNTRACKED],
                                            "linker flavor"),
@@ -706,7 +706,7 @@ fn parse_src_file_hash(slot: &mut Option<SourceFileHashAlgorithm>, v: Option<&st
         "when debug-printing compiler state, do not include spans"), // o/w tests have closure@path
     identify_regions: bool = (false, parse_bool, [UNTRACKED],
         "make unnamed regions display as '# (where # is some non-ident unique id)"),
-    borrowck: Option<String> = (None, parse_opt_string, [UNTRACKED],
+    borrowck: String = ("migrate".to_string(), parse_string, [UNTRACKED],
         "select which borrowck is used (`mir` or `migrate`)"),
     time_passes: bool = (false, parse_bool, [UNTRACKED],
         "measure time of each rustc pass"),
@@ -806,7 +806,7 @@ fn parse_src_file_hash(slot: &mut Option<SourceFileHashAlgorithm>, v: Option<&st
         "print the result of the monomorphization collection pass"),
     mir_opt_level: usize = (1, parse_uint, [TRACKED],
         "set the MIR optimization level (0-3, default: 1)"),
-    mutable_noalias: Option<bool> = (None, parse_opt_bool, [TRACKED],
+    mutable_noalias: bool = (false, parse_bool, [TRACKED],
         "emit noalias metadata for mutable references (default: no)"),
     dump_mir: Option<String> = (None, parse_opt_string, [UNTRACKED],
         "dump MIR state to file.
@@ -816,7 +816,7 @@ fn parse_src_file_hash(slot: &mut Option<SourceFileHashAlgorithm>, v: Option<&st
         `foo & ConstProp` only the 'ConstProp' pass for function names containing 'foo',
         `foo | bar` all passes for function names containing 'foo' or 'bar'."),
 
-    dump_mir_dir: String = (String::from("mir_dump"), parse_string, [UNTRACKED],
+    dump_mir_dir: String = ("mir_dump".to_string(), parse_string, [UNTRACKED],
         "the directory the MIR is dumped into"),
     dump_mir_graphviz: bool = (false, parse_bool, [UNTRACKED],
         "in addition to `.mir` files, create graphviz `.dot` files"),
@@ -890,13 +890,16 @@ fn parse_src_file_hash(slot: &mut Option<SourceFileHashAlgorithm>, v: Option<&st
         `hir,typed` (HIR with types for each node),
         `hir-tree` (dump the raw HIR),
         `mir` (the MIR), or `mir-cfg` (graphviz formatted MIR)"),
-    run_dsymutil: Option<bool> = (None, parse_opt_bool, [TRACKED],
+    // The default historical behavior was to always run dsymutil, so we're
+    // preserving that temporarily, but we're likely to switch the default
+    // soon.
+    run_dsymutil: bool = (true, parse_bool, [TRACKED],
         "run `dsymutil` and delete intermediate object files"),
-    ui_testing: Option<bool> = (None, parse_opt_bool, [UNTRACKED],
+    ui_testing: bool = (false, parse_bool, [UNTRACKED],
         "format compiler diagnostics in a way that's better suitable for UI testing"),
     embed_bitcode: bool = (false, parse_bool, [TRACKED],
         "embed LLVM bitcode in object files"),
-    strip_debuginfo_if_disabled: Option<bool> = (None, parse_opt_bool, [TRACKED],
+    strip_debuginfo_if_disabled: bool = (false, parse_bool, [TRACKED],
         "tell the linker to strip debuginfo when building without debuginfo enabled"),
     share_generics: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "make the current crate share its generic instantiations"),
@@ -936,7 +939,7 @@ fn parse_src_file_hash(slot: &mut Option<SourceFileHashAlgorithm>, v: Option<&st
     insert_sideeffect: bool = (false, parse_bool, [TRACKED],
         "fix undefined behavior when a thread doesn't eventually make progress \
          (such as entering an empty infinite loop) by inserting llvm.sideeffect"),
-    deduplicate_diagnostics: Option<bool> = (None, parse_opt_bool, [UNTRACKED],
+    deduplicate_diagnostics: bool = (true, parse_bool, [UNTRACKED],
         "deduplicate identical diagnostics"),
     control_flow_guard: CFGuard = (CFGuard::Disabled, parse_cfguard, [UNTRACKED],
         "use Windows Control Flow Guard (`disabled`, `nochecks` or `checks`)"),
@@ -944,9 +947,9 @@ fn parse_src_file_hash(slot: &mut Option<SourceFileHashAlgorithm>, v: Option<&st
         "compile without linking"),
     link_only: bool = (false, parse_bool, [TRACKED],
         "link the `.rlink` file generated by `-Z no-link`"),
-    new_llvm_pass_manager: Option<bool> = (None, parse_opt_bool, [TRACKED],
+    new_llvm_pass_manager: bool = (false, parse_bool, [TRACKED],
         "use new LLVM pass manager"),
-    link_native_libraries: Option<bool> = (None, parse_opt_bool, [UNTRACKED],
+    link_native_libraries: bool = (true, parse_bool, [UNTRACKED],
         "link native libraries in the linker invocation"),
     src_hash_algorithm: Option<SourceFileHashAlgorithm> = (None, parse_src_file_hash, [TRACKED],
         "hash algorithm of source files in debug info (`md5`, or `sha1`)"),

src/librustc_session/session.rs

@@ -899,7 +899,7 @@ fn default_emitter(
                     short,
                     macro_backtrace,
                 );
-                Box::new(emitter.ui_testing(sopts.debugging_opts.ui_testing()))
+                Box::new(emitter.ui_testing(sopts.debugging_opts.ui_testing))
             } else {
                 let emitter = match dst {
                     None => EmitterWriter::stderr(
@@ -920,7 +920,7 @@ fn default_emitter(
                         macro_backtrace,
                     ),
                 };
-                Box::new(emitter.ui_testing(sopts.debugging_opts.ui_testing()))
+                Box::new(emitter.ui_testing(sopts.debugging_opts.ui_testing))
             }
         }
         (config::ErrorOutputType::Json { pretty, json_rendered }, None) => Box::new(
@@ -931,7 +931,7 @@ fn default_emitter(
                 json_rendered,
                 macro_backtrace,
             )
-            .ui_testing(sopts.debugging_opts.ui_testing()),
+            .ui_testing(sopts.debugging_opts.ui_testing),
         ),
         (config::ErrorOutputType::Json { pretty, json_rendered }, Some(dst)) => Box::new(
             JsonEmitter::new(
@@ -942,7 +942,7 @@ fn default_emitter(
                 json_rendered,
                 macro_backtrace,
             )
-            .ui_testing(sopts.debugging_opts.ui_testing()),
+            .ui_testing(sopts.debugging_opts.ui_testing),
         ),
     }
 }

src/librustdoc/core.rs

@@ -185,7 +185,7 @@ pub fn new_handler(
                     debugging_opts.terminal_width,
                     false,
                 )
-                .ui_testing(debugging_opts.ui_testing()),
+                .ui_testing(debugging_opts.ui_testing),
             )
         }
         ErrorOutputType::Json { pretty, json_rendered } => {
@@ -194,7 +194,7 @@ pub fn new_handler(
             });
             Box::new(
                 JsonEmitter::stderr(None, source_map, pretty, json_rendered, false)
-                    .ui_testing(debugging_opts.ui_testing()),
+                    .ui_testing(debugging_opts.ui_testing),
             )
         }
     };