Support true and false as boolean flag params

Implements MCP 577.

compiler/rustc_session/src/options.rs

@@ -349,7 +349,7 @@ fn build_options<O: Default>(
 #[allow(non_upper_case_globals)]
 mod desc {
     pub const parse_no_flag: &str = "no value";
-    pub const parse_bool: &str = "one of: `y`, `yes`, `on`, `n`, `no`, or `off`";
+    pub const parse_bool: &str = "one of: `y`, `yes`, `on`, `true`, `n`, `no`, `off` or `false`";
     pub const parse_opt_bool: &str = parse_bool;
     pub const parse_string: &str = "a string";
     pub const parse_opt_string: &str = parse_string;
@@ -432,11 +432,11 @@ mod parse {
     /// Use this for any boolean option that has a static default.
     pub(crate) fn parse_bool(slot: &mut bool, v: Option<&str>) -> bool {
         match v {
-            Some("y") | Some("yes") | Some("on") | None => {
+            Some("y") | Some("yes") | Some("on") | Some("true") | None => {
                 *slot = true;
                 true
             }
-            Some("n") | Some("no") | Some("off") => {
+            Some("n") | Some("no") | Some("off") | Some("false") => {
                 *slot = false;
                 true
             }
@@ -449,11 +449,11 @@ mod parse {
     /// other factors, such as other options, or target options.)
     pub(crate) fn parse_opt_bool(slot: &mut Option<bool>, v: Option<&str>) -> bool {
         match v {
-            Some("y") | Some("yes") | Some("on") | None => {
+            Some("y") | Some("yes") | Some("on") | Some("true") | None => {
                 *slot = Some(true);
                 true
             }
-            Some("n") | Some("no") | Some("off") => {
+            Some("n") | Some("no") | Some("off") | Some("false") => {
                 *slot = Some(false);
                 true
             }

tests/codegen/issue-75659.rs

@@ -1,7 +1,7 @@
 // This test checks that the call to memchr/slice_contains is optimized away
 // when searching in small slices.
 
-// compile-flags: -O -Zinline-mir=no
+// compile-flags: -O -Zinline-mir=false
 // only-x86_64
 
 #![crate_type = "lib"]

tests/ui/lint/reasons-forbidden.rs

@@ -8,7 +8,7 @@
 //
 // The test is much cleaner if we deduplicate, though.
 
-// compile-flags: -Z deduplicate-diagnostics=yes
+// compile-flags: -Z deduplicate-diagnostics=true
 
 #![forbid(
     unsafe_code,

tests/ui/numbers-arithmetic/next-power-of-two-overflow-debug.rs

@@ -1,5 +1,5 @@
 // run-pass
-// compile-flags: -C debug_assertions=yes
+// compile-flags: -C debug_assertions=true
 // needs-unwind
 // ignore-emscripten dies with an LLVM error
 

tests/ui/rfc-2091-track-caller/call-chain.rs

@@ -1,6 +1,6 @@
 // run-pass
 // revisions: default mir-opt
-//[default] compile-flags: -Zinline-mir=no
+//[default] compile-flags: -Zinline-mir=false
 //[mir-opt] compile-flags: -Zmir-opt-level=4
 
 use std::panic::Location;