Auto merge of #122597 - pacak:master, r=bjorn3

Show files produced by `--emit foo` in json artifact notifications

Right now it is possible to ask `rustc` to save some intermediate representation into one or more files with `--emit=foo`, but figuring out what exactly was produced is difficult. This pull request adds information about `llvm_ir` and `asm` intermediate files into notifications produced by `--json=artifacts`.

Related discussion: https://internals.rust-lang.org/t/easier-access-to-files-generated-by-emit-foo/20477

Motivation - `cargo-show-asm` parses those intermediate files and presents them in a user friendly way, but right now I have to apply some dirty hacks. Hacks make behavior confusing: https://github.com/hintron/computer-enhance/issues/35

This pull request introduces a new behavior: now `rustc` will emit a new artifact notification for every artifact type user asked to `--emit`, for example for `--emit asm` those will include all the `.s` files.

Most users won't notice this behavior, to be affected by it all of the following must hold:
- user must use `rustc` binary directly (when `cargo` invokes `rustc` - it consumes artifact notifications and doesn't emit anything)
- user must specify both `--emit xxx` and `--json artifacts`
- user must refuse to handle unknown artifact types
- user must disable incremental compilation (or deal with it better than cargo does, or use a workaround like `save-temps`) in order not to hit #88829 / #89149

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -717,6 +717,29 @@ fn produce_final_output_artifacts(
         }
     }
 
+    if sess.opts.json_artifact_notifications {
+        if compiled_modules.modules.len() == 1 {
+            compiled_modules.modules[0].for_each_output(|_path, ty| {
+                if sess.opts.output_types.contains_key(&ty) {
+                    let descr = ty.shorthand();
+                    // for single cgu file is renamed to drop cgu specific suffix
+                    // so we regenerate it the same way
+                    let path = crate_output.path(ty);
+                    sess.dcx().emit_artifact_notification(path.as_path(), descr);
+                }
+            });
+        } else {
+            for module in &compiled_modules.modules {
+                module.for_each_output(|path, ty| {
+                    if sess.opts.output_types.contains_key(&ty) {
+                        let descr = ty.shorthand();
+                        sess.dcx().emit_artifact_notification(&path, descr);
+                    }
+                });
+            }
+        }
+    }
+
     // We leave the following files around by default:
     //  - #crate#.o
     //  - #crate#.crate.metadata.o

compiler/rustc_codegen_ssa/src/lib.rs

@@ -106,6 +106,24 @@ pub struct CompiledModule {
     pub llvm_ir: Option<PathBuf>,  // --emit=llvm-ir, llvm-bc is in bytecode
 }
 
+impl CompiledModule {
+    /// Call `emit` function with every artifact type currently compiled
+    pub fn for_each_output(&self, mut emit: impl FnMut(&Path, OutputType)) {
+        if let Some(path) = self.object.as_deref() {
+            emit(path, OutputType::Object);
+        }
+        if let Some(path) = self.bytecode.as_deref() {
+            emit(path, OutputType::Bitcode);
+        }
+        if let Some(path) = self.llvm_ir.as_deref() {
+            emit(path, OutputType::LlvmAssembly);
+        }
+        if let Some(path) = self.assembly.as_deref() {
+            emit(path, OutputType::Assembly);
+        }
+    }
+}
+
 pub struct CachedModuleCodegen {
     pub name: String,
     pub source: WorkProduct,