Rollup of 2 pull requests

compiler/rustc_codegen_llvm/messages.ftl

@@ -1,4 +1,5 @@
 codegen_llvm_autodiff_without_enable = using the autodiff feature requires -Z autodiff=Enable
+codegen_llvm_autodiff_without_lto = using the autodiff feature requires setting `lto="fat"` in your Cargo.toml
 
 codegen_llvm_copy_bitcode = failed to copy bitcode to object file: {$err}
 

compiler/rustc_codegen_llvm/src/errors.rs

@@ -32,6 +32,10 @@ impl<G: EmissionGuarantee> Diagnostic<'_, G> for ParseTargetMachineConfig<'_> {
     }
 }
 
+#[derive(Diagnostic)]
+#[diag(codegen_llvm_autodiff_without_lto)]
+pub(crate) struct AutoDiffWithoutLto;
+
 #[derive(Diagnostic)]
 #[diag(codegen_llvm_autodiff_without_enable)]
 pub(crate) struct AutoDiffWithoutEnable;

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -25,7 +25,7 @@ use crate::abi::FnAbiLlvmExt;
 use crate::builder::Builder;
 use crate::builder::autodiff::{adjust_activity_to_abi, generate_enzyme_call};
 use crate::context::CodegenCx;
-use crate::errors::AutoDiffWithoutEnable;
+use crate::errors::{AutoDiffWithoutEnable, AutoDiffWithoutLto};
 use crate::llvm::{self, Metadata, Type, Value};
 use crate::type_of::LayoutLlvmExt;
 use crate::va_arg::emit_va_arg;
@@ -1146,6 +1146,9 @@ fn codegen_autodiff<'ll, 'tcx>(
     if !tcx.sess.opts.unstable_opts.autodiff.contains(&rustc_session::config::AutoDiff::Enable) {
         let _ = tcx.dcx().emit_almost_fatal(AutoDiffWithoutEnable);
     }
+    if tcx.sess.lto() != rustc_session::config::Lto::Fat {
+        let _ = tcx.dcx().emit_almost_fatal(AutoDiffWithoutLto);
+    }
 
     let fn_args = instance.args;
     let callee_ty = instance.ty(tcx, bx.typing_env());

compiler/rustc_session/src/session.rs

@@ -594,14 +594,6 @@ impl Session {
 
     /// Calculates the flavor of LTO to use for this compilation.
     pub fn lto(&self) -> config::Lto {
-        // Autodiff currently requires fat-lto to have access to the llvm-ir of all (indirectly) used functions and types.
-        // fat-lto is the easiest solution to this requirement, but quite expensive.
-        // FIXME(autodiff): Make autodiff also work with embed-bc instead of fat-lto.
-        // Don't apply fat-lto to proc-macro crates as they cannot use fat-lto without -Zdylib-lto
-        if self.opts.autodiff_enabled() && !self.opts.crate_types.contains(&CrateType::ProcMacro) {
-            return config::Lto::Fat;
-        }
-
         // If our target has codegen requirements ignore the command line
         if self.target.requires_lto {
             return config::Lto::Fat;

tests/ui/autodiff/no_lto_flag.no_lto.stderr

@@ -0,0 +1,4 @@
+error: using the autodiff feature requires setting `lto="fat"` in your Cargo.toml
+
+error: aborting due to 1 previous error
+

tests/ui/autodiff/no_lto_flag.rs

@@ -0,0 +1,31 @@
+//@ needs-enzyme
+//@ no-prefer-dynamic
+//@ revisions: with_lto no_lto
+//@[with_lto] compile-flags: -Zautodiff=Enable -C opt-level=3  -Clto=fat
+//@[no_lto] compile-flags: -Zautodiff=Enable -C opt-level=3 -Clto=thin
+
+#![feature(autodiff)]
+//@[no_lto] build-fail
+//@[with_lto] build-pass
+
+// Autodiff requires users to enable lto=fat (for now).
+// In the past, autodiff did not run if users forget to enable fat-lto, which caused functions to
+// returning zero-derivatives. That's obviously wrong and confusing to users. We now added a check
+// which will abort compilation instead.
+
+use std::autodiff::autodiff_reverse;
+//[no_lto]~? ERROR using the autodiff feature requires setting `lto="fat"` in your Cargo.toml
+
+#[autodiff_reverse(d_square, Duplicated, Active)]
+fn square(x: &f64) -> f64 {
+    *x * *x
+}
+
+fn main() {
+    let xf64: f64 = std::hint::black_box(3.0);
+
+    let mut df_dxf64: f64 = std::hint::black_box(0.0);
+
+    let _output_f64 = d_square(&xf64, &mut df_dxf64, 1.0);
+    assert_eq!(6.0, df_dxf64);
+}

tests/ui/proc-macro/auxiliary/nonfatal-parsing-body.rs

@@ -0,0 +1,143 @@
+use std::fmt::Debug;
+use std::panic::catch_unwind;
+use std::str::FromStr;
+
+use proc_macro::*;
+
+use self::Mode::*;
+
+// FIXME: all cases should become `NormalOk` or `NormalErr`
+#[derive(PartialEq, Clone, Copy)]
+enum Mode {
+    NormalOk,
+    NormalErr,
+    OtherError,
+    OtherWithPanic,
+}
+
+fn parse<T>(s: &str, mode: Mode)
+where
+    T: FromStr<Err = LexError> + Debug,
+{
+    match mode {
+        NormalOk => {
+            let t = T::from_str(s);
+            println!("{:?}", t);
+            assert!(t.is_ok());
+        }
+        NormalErr => {
+            let t = T::from_str(s);
+            println!("{:?}", t);
+            assert!(t.is_err());
+        }
+        OtherError => {
+            println!("{:?}", T::from_str(s));
+        }
+        OtherWithPanic => {
+            if catch_unwind(|| println!("{:?}", T::from_str(s))).is_ok() {
+                eprintln!("{s} did not panic");
+            }
+        }
+    }
+}
+
+fn stream(s: &str, mode: Mode) {
+    parse::<TokenStream>(s, mode);
+}
+
+fn lit(s: &str, mode: Mode) {
+    parse::<Literal>(s, mode);
+    if mode == NormalOk {
+        let Ok(lit) = Literal::from_str(s) else {
+            panic!("literal was not ok");
+        };
+        let Ok(stream) = TokenStream::from_str(s) else {
+            panic!("tokenstream was not ok, but literal was");
+        };
+        let Some(tree) = stream.into_iter().next() else {
+            panic!("tokenstream should have a tokentree");
+        };
+        if let TokenTree::Literal(tokenstream_lit) = tree {
+            assert_eq!(lit.to_string(), tokenstream_lit.to_string());
+        }
+    }
+}
+
+pub fn run() {
+    // returns Ok(valid instance)
+    lit("123", NormalOk);
+    lit("\"ab\"", NormalOk);
+    lit("\'b\'", NormalOk);
+    lit("'b'", NormalOk);
+    lit("b\"b\"", NormalOk);
+    lit("c\"b\"", NormalOk);
+    lit("cr\"b\"", NormalOk);
+    lit("b'b'", NormalOk);
+    lit("256u8", NormalOk);
+    lit("-256u8", NormalOk);
+    stream("-256u8", NormalOk);
+    lit("0b11111000000001111i16", NormalOk);
+    lit("0xf32", NormalOk);
+    lit("0b0f32", NormalOk);
+    lit("2E4", NormalOk);
+    lit("2.2E-4f64", NormalOk);
+    lit("18u8E", NormalOk);
+    lit("18.0u8E", NormalOk);
+    lit("cr#\"// /* // \n */\"#", NormalOk);
+    lit("'\\''", NormalOk);
+    lit("'\\\''", NormalOk);
+    lit(&format!("r{0}\"a\"{0}", "#".repeat(255)), NormalOk);
+    stream("fn main() { println!(\"Hello, world!\") }", NormalOk);
+    stream("18.u8E", NormalOk);
+    stream("18.0f32", NormalOk);
+    stream("18.0f34", NormalOk);
+    stream("18.bu8", NormalOk);
+    stream("3//\n4", NormalOk);
+    stream(
+        "\'c\'/*\n
+    */",
+        NormalOk,
+    );
+    stream("/*a*/ //", NormalOk);
+
+    println!("### ERRORS");
+
+    // returns Err(LexError)
+    lit("\'c\'/**/", NormalErr);
+    lit(" 0", NormalErr);
+    lit("0 ", NormalErr);
+    lit("0//", NormalErr);
+    lit("3//\n4", NormalErr);
+    lit("18.u8E", NormalErr);
+    lit("/*a*/ //", NormalErr);
+    // FIXME: all of the cases below should return an Err and emit no diagnostics, but don't yet.
+
+    // emits diagnostics and returns LexError
+    lit("r'r'", OtherError);
+    lit("c'r'", OtherError);
+
+    // emits diagnostic and returns a seemingly valid tokenstream
+    stream("r'r'", OtherError);
+    stream("c'r'", OtherError);
+
+    for parse in [stream as fn(&str, Mode), lit] {
+        // emits diagnostic(s), then panics
+        parse("1 ) 2", OtherWithPanic);
+        parse("( x  [ ) ]", OtherWithPanic);
+        parse("r#", OtherWithPanic);
+
+        // emits diagnostic(s), then returns Ok(Literal { kind: ErrWithGuar, .. })
+        parse("0b2", OtherError);
+        parse("0bf32", OtherError);
+        parse("0b0.0f32", OtherError);
+        parse("'\''", OtherError);
+        parse(
+            "'
+'", OtherError,
+        );
+        parse(&format!("r{0}\"a\"{0}", "#".repeat(256)), OtherWithPanic);
+
+        // emits diagnostic, then, when parsing as a lit, returns LexError, otherwise ErrWithGuar
+        parse("/*a*/ 0b2 //", OtherError);
+    }
+}

tests/ui/proc-macro/auxiliary/nonfatal-parsing.rs

@@ -0,0 +1,11 @@
+extern crate proc_macro;
+use proc_macro::*;
+
+#[path = "nonfatal-parsing-body.rs"]
+mod body;
+
+#[proc_macro]
+pub fn run(_: TokenStream) -> TokenStream {
+    body::run();
+    TokenStream::new()
+}

tests/ui/proc-macro/nonfatal-parsing.rs

@@ -0,0 +1,19 @@
+//@ proc-macro: nonfatal-parsing.rs
+//@ needs-unwind
+//@ edition: 2024
+//@ dont-require-annotations: ERROR
+//@ ignore-backends: gcc
+// FIXME: should be a run-pass test once invalidly parsed tokens no longer result in diagnostics
+
+extern crate proc_macro;
+extern crate nonfatal_parsing;
+
+#[path = "auxiliary/nonfatal-parsing-body.rs"]
+mod body;
+
+fn main() {
+    nonfatal_parsing::run!();
+    // FIXME: enable this once the standalone backend exists
+    // https://github.com/rust-lang/rust/issues/130856
+    // body::run();
+}