diff --git a/Cargo.lock b/Cargo.lock
index 234d709f3c315..91fce715c8cd1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3789,7 +3789,6 @@ dependencies = [
  "rustc_errors",
  "rustc_expand",
  "rustc_feature",
- "rustc_fluent_macro",
  "rustc_hir_analysis",
  "rustc_hir_pretty",
  "rustc_hir_typeck",
diff --git a/compiler/rustc_driver_impl/Cargo.toml b/compiler/rustc_driver_impl/Cargo.toml
index c160240a18a77..d97c552b412b5 100644
--- a/compiler/rustc_driver_impl/Cargo.toml
+++ b/compiler/rustc_driver_impl/Cargo.toml
@@ -21,7 +21,6 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_expand = { path = "../rustc_expand" }
 rustc_feature = { path = "../rustc_feature" }
-rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_hir_analysis = { path = "../rustc_hir_analysis" }
 rustc_hir_pretty = { path = "../rustc_hir_pretty" }
 rustc_hir_typeck = { path = "../rustc_hir_typeck" }
diff --git a/compiler/rustc_driver_impl/messages.ftl b/compiler/rustc_driver_impl/messages.ftl
deleted file mode 100644
index b62cdc35f5130..0000000000000
--- a/compiler/rustc_driver_impl/messages.ftl
+++ /dev/null
@@ -1,29 +0,0 @@
-driver_impl_cant_emit_mir = could not emit MIR: {$error}
-
-driver_impl_ice = the compiler unexpectedly panicked. this is a bug.
-driver_impl_ice_bug_report = we would appreciate a bug report: {$bug_report_url}
-driver_impl_ice_bug_report_internal_feature = using internal features is not supported and expected to cause internal compiler errors when used incorrectly
-driver_impl_ice_bug_report_update_note = please make sure that you have updated to the latest nightly
-driver_impl_ice_exclude_cargo_defaults = some of the compiler flags provided by cargo are hidden
-
-driver_impl_ice_flags = compiler flags: {$flags}
-driver_impl_ice_path = please attach the file at `{$path}` to your bug report
-driver_impl_ice_path_error = the ICE couldn't be written to `{$path}`: {$error}
-driver_impl_ice_path_error_env = the environment variable `RUSTC_ICE` is set to `{$env_var}`
-driver_impl_ice_version = rustc {$version} running on {$triple}
-
-driver_impl_rlink_corrupt_file = corrupt metadata encountered in `{$file}`
-
-driver_impl_rlink_empty_version_number = the input does not contain version number
-
-driver_impl_rlink_encoding_version_mismatch = .rlink file was produced with encoding version `{$version_array}`, but the current version is `{$rlink_version}`
-
-driver_impl_rlink_no_a_file = rlink must be a file
-
-driver_impl_rlink_rustc_version_mismatch = .rlink file was produced by rustc version `{$rustc_version}`, but the current version is `{$current_version}`
-
-driver_impl_rlink_unable_to_read = failed to read rlink file: `{$err}`
-
-driver_impl_rlink_wrong_file_type = the input does not look like a .rlink file
-
-driver_impl_unstable_feature_usage = cannot dump feature usage metrics: {$error}
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 38ee87601614b..b163ae2068a66 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -108,15 +108,12 @@ use crate::session_diagnostics::{
     RLinkWrongFileType, RlinkCorruptFile, RlinkNotAFile, RlinkUnableToRead, UnstableFeatureUsage,
 };
 
-rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
-
 pub fn default_translator() -> Translator {
     Translator::with_fallback_bundle(DEFAULT_LOCALE_RESOURCES.to_vec(), false)
 }
 
 pub static DEFAULT_LOCALE_RESOURCES: &[&str] = &[
     // tidy-alphabetical-start
-    crate::DEFAULT_LOCALE_RESOURCE,
     rustc_ast_lowering::DEFAULT_LOCALE_RESOURCE,
     rustc_ast_passes::DEFAULT_LOCALE_RESOURCE,
     rustc_attr_parsing::DEFAULT_LOCALE_RESOURCE,
@@ -491,10 +488,18 @@ fn handle_explain(early_dcx: &EarlyDiagCtxt, registry: Registry, code: &str, col
             }
             text.push('\n');
         }
+
+        // If output is a terminal, use a pager to display the content.
         if io::stdout().is_terminal() {
             show_md_content_with_pager(&text, color);
         } else {
-            safe_print!("{text}");
+            // Otherwise, if the user has requested colored output
+            // print the content in color, else print the md content.
+            if color == ColorConfig::Always {
+                show_colored_md_content(&text);
+            } else {
+                safe_print!("{text}");
+            }
         }
     } else {
         early_dcx.early_fatal(format!("{code} is not a valid error code"));
@@ -564,6 +569,33 @@ fn show_md_content_with_pager(content: &str, color: ColorConfig) {
     safe_print!("{content}");
 }
 
+/// Prints the markdown content with colored output.
+///
+/// This function is used when the output is not a terminal,
+/// but the user has requested colored output with `--color=always`.
+fn show_colored_md_content(content: &str) {
+    // Try to prettify the raw markdown text.
+    let mut pretty_data = {
+        let mdstream = markdown::MdStream::parse_str(content);
+        let bufwtr = markdown::create_stdout_bufwtr();
+        let mut mdbuf = Vec::new();
+        if mdstream.write_anstream_buf(&mut mdbuf, Some(&highlighter::highlight)).is_ok() {
+            Some((bufwtr, mdbuf))
+        } else {
+            None
+        }
+    };
+
+    if let Some((bufwtr, mdbuf)) = &mut pretty_data
+        && bufwtr.write_all(&mdbuf).is_ok()
+    {
+        return;
+    }
+
+    // Everything failed. Print the raw markdown text.
+    safe_print!("{content}");
+}
+
 fn process_rlink(sess: &Session, compiler: &interface::Compiler) {
     assert!(sess.opts.unstable_opts.link_only);
     let dcx = sess.dcx();
diff --git a/compiler/rustc_driver_impl/src/session_diagnostics.rs b/compiler/rustc_driver_impl/src/session_diagnostics.rs
index 774221fd396a6..565c176645dee 100644
--- a/compiler/rustc_driver_impl/src/session_diagnostics.rs
+++ b/compiler/rustc_driver_impl/src/session_diagnostics.rs
@@ -3,82 +3,88 @@ use std::error::Error;
 use rustc_macros::{Diagnostic, Subdiagnostic};
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_cant_emit_mir)]
+#[diag("could not emit MIR: {$error}")]
 pub struct CantEmitMIR {
     pub error: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_rlink_unable_to_read)]
+#[diag("failed to read rlink file: `{$err}`")]
 pub(crate) struct RlinkUnableToRead {
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_rlink_wrong_file_type)]
+#[diag("the input does not look like a .rlink file")]
 pub(crate) struct RLinkWrongFileType;
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_rlink_empty_version_number)]
+#[diag("the input does not contain version number")]
 pub(crate) struct RLinkEmptyVersionNumber;
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_rlink_encoding_version_mismatch)]
+#[diag(
+    ".rlink file was produced with encoding version `{$version_array}`, but the current version is `{$rlink_version}`"
+)]
 pub(crate) struct RLinkEncodingVersionMismatch {
     pub version_array: String,
     pub rlink_version: u32,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_rlink_rustc_version_mismatch)]
+#[diag(
+    ".rlink file was produced by rustc version `{$rustc_version}`, but the current version is `{$current_version}`"
+)]
 pub(crate) struct RLinkRustcVersionMismatch<'a> {
     pub rustc_version: String,
     pub current_version: &'a str,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_rlink_no_a_file)]
+#[diag("rlink must be a file")]
 pub(crate) struct RlinkNotAFile;
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_rlink_corrupt_file)]
+#[diag("corrupt metadata encountered in `{$file}`")]
 pub(crate) struct RlinkCorruptFile<'a> {
     pub file: &'a std::path::Path,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_ice)]
+#[diag("the compiler unexpectedly panicked. this is a bug.")]
 pub(crate) struct Ice;
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_ice_bug_report)]
+#[diag("we would appreciate a bug report: {$bug_report_url}")]
 pub(crate) struct IceBugReport<'a> {
     pub bug_report_url: &'a str,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_ice_bug_report_update_note)]
+#[diag("please make sure that you have updated to the latest nightly")]
 pub(crate) struct UpdateNightlyNote;
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_ice_bug_report_internal_feature)]
+#[diag(
+    "using internal features is not supported and expected to cause internal compiler errors when used incorrectly"
+)]
 pub(crate) struct IceBugReportInternalFeature;
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_ice_version)]
+#[diag("rustc {$version} running on {$triple}")]
 pub(crate) struct IceVersion<'a> {
     pub version: &'a str,
     pub triple: &'a str,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_ice_path)]
+#[diag("please attach the file at `{$path}` to your bug report")]
 pub(crate) struct IcePath {
     pub path: std::path::PathBuf,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_ice_path_error)]
+#[diag("the ICE couldn't be written to `{$path}`: {$error}")]
 pub(crate) struct IcePathError {
     pub path: std::path::PathBuf,
     pub error: String,
@@ -87,23 +93,23 @@ pub(crate) struct IcePathError {
 }
 
 #[derive(Subdiagnostic)]
-#[note(driver_impl_ice_path_error_env)]
+#[note("the environment variable `RUSTC_ICE` is set to `{$env_var}`")]
 pub(crate) struct IcePathErrorEnv {
     pub env_var: std::path::PathBuf,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_ice_flags)]
+#[diag("compiler flags: {$flags}")]
 pub(crate) struct IceFlags {
     pub flags: String,
 }
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_ice_exclude_cargo_defaults)]
+#[diag("some of the compiler flags provided by cargo are hidden")]
 pub(crate) struct IceExcludeCargoDefaults;
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_unstable_feature_usage)]
+#[diag("cannot dump feature usage metrics: {$error}")]
 pub(crate) struct UnstableFeatureUsage {
     pub error: Box<dyn Error>,
 }
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index ef90b81fb2a73..1804490a5f12c 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -1438,7 +1438,7 @@ impl<'test> TestCx<'test> {
         } else if aux_type.is_some() {
             panic!("aux_type {aux_type:?} not expected");
         } else if aux_props.no_prefer_dynamic {
-            (AuxType::Dylib, None)
+            (AuxType::Lib, None)
         } else if self.config.target.contains("emscripten")
             || (self.config.target.contains("musl")
                 && !aux_props.force_host
diff --git a/tests/ui/compiletest-self-test/auxiliary/no_prefer_dynamic_lib.rs b/tests/ui/compiletest-self-test/auxiliary/no_prefer_dynamic_lib.rs
new file mode 100644
index 0000000000000..6688dadbab24f
--- /dev/null
+++ b/tests/ui/compiletest-self-test/auxiliary/no_prefer_dynamic_lib.rs
@@ -0,0 +1,10 @@
+//@ no-prefer-dynamic
+
+//! Since this is `no-prefer-dynamic` we expect compiletest to _not_ look for
+//! this create as `libno_prefer_dynamic_lib.so`.
+
+#![crate_type = "rlib"]
+
+pub fn return_42() -> i32 {
+    42
+}
diff --git a/tests/ui/compiletest-self-test/no-prefer-dynamic-means-no-so.rs b/tests/ui/compiletest-self-test/no-prefer-dynamic-means-no-so.rs
new file mode 100644
index 0000000000000..b7e8fae506c39
--- /dev/null
+++ b/tests/ui/compiletest-self-test/no-prefer-dynamic-means-no-so.rs
@@ -0,0 +1,10 @@
+//! Since we and our `aux-crate` is `no-prefer-dynamic`, we expect compiletest
+//! to _not_ look for `libno_prefer_dynamic_lib.so`.
+
+//@ check-pass
+//@ no-prefer-dynamic
+//@ aux-crate: no_prefer_dynamic_lib=no_prefer_dynamic_lib.rs
+
+fn main() {
+    no_prefer_dynamic_lib::return_42();
+}
diff --git a/tests/ui/explain/ensure-color-always-works.rs b/tests/ui/explain/ensure-color-always-works.rs
new file mode 100644
index 0000000000000..81ee716e78b4d
--- /dev/null
+++ b/tests/ui/explain/ensure-color-always-works.rs
@@ -0,0 +1,2 @@
+//@ compile-flags: --explain E0591 --color always --error-format=human
+//@ check-pass
diff --git a/tests/ui/explain/ensure-color-always-works.stdout b/tests/ui/explain/ensure-color-always-works.stdout
new file mode 100644
index 0000000000000..7e5358bcfb7ec
--- /dev/null
+++ b/tests/ui/explain/ensure-color-always-works.stdout
@@ -0,0 +1,50 @@
+Per ]8;;https://github.com/rust-lang/rfcs/blob/master/text/0401-coercions.md\RFC 401]8;;\, if you have a function declaration foo:
+
+struct S;
+
+// For the purposes of this explanation, all of these
+// different kinds of `fn` declarations are equivalent:
+
+fn foo(x: S) { /* ... */ }
+extern "C" {
+    fn foo(x: S);
+}
+impl S {
+    fn foo(self) { /* ... */ }
+}
+
+the type of foo is not fn(S), as one might expect. Rather, it is a unique, zero-sized marker type written here as typeof(foo). However, typeof(foo)
+ can be coerced to a function pointer fn(S), so you rarely notice this:
+
+let x: fn(S) = foo; // OK, coerces
+
+The reason that this matter is that the type fn(S) is not specific to any particular function: it's a function pointer. So calling x()
+results in a virtual call, whereas foo() is statically dispatched, because the type of foo tells us precisely what function is being called.
+
+As noted above, coercions mean that most code doesn't have to be concerned with this distinction. However, you can tell the difference when
+using transmute to convert a fn item into a fn pointer.
+
+This is sometimes done as part of an FFI:
+
+extern "C" fn foo(userdata: Box<i32>) {
+    /* ... */
+}
+
+unsafe {
+    let f: extern "C" fn(*mut i32) = transmute(foo);
+    callback(f);
+}
+
+Here, transmute is being used to convert the types of the fn arguments. This pattern is incorrect because the type of foo is a function item 
+(typeof(foo)), which is zero-sized, and the target type (fn()) is a function pointer, which is not zero-sized. This pattern should be
+rewritten. There are a few possible ways to do this:
+
+*   change the original fn declaration to match the expected signature, and do the cast in the fn body (the preferred option)
+*   cast the fn item of a fn pointer before calling transmute, as shown here:
+
+let f: extern "C" fn(*mut i32) = transmute(foo as extern "C" fn(_));
+let f: extern "C" fn(*mut i32) = transmute(foo as usize); // works too
+
+The same applies to transmutes to *mut fn(), which were observed in practice. Note though that use of this type is generally incorrect. The
+intention is typically to describe a function pointer, but just fn() alone suffices for that. *mut fn() is a pointer to a fn pointer. (Since these
+values are typically just passed to C code, however, this rarely makes a difference in practice.)