Emit only necessary compilation options in save-analysis

This is `command`, `directory` and `output` file.

src/Cargo.lock

@@ -2373,6 +2373,7 @@ dependencies = [
  "rls-span 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc 0.0.0",
  "rustc-serialize 0.3.24 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc_codegen_utils 0.0.0",
  "rustc_data_structures 0.0.0",
  "rustc_target 0.0.0",
  "rustc_typeck 0.0.0",

src/librustc_save_analysis/Cargo.toml

@@ -12,6 +12,7 @@ crate-type = ["dylib"]
 log = "0.4"
 rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
+rustc_codegen_utils = { path = "../librustc_codegen_utils" }
 rustc_target = { path = "../librustc_target" }
 rustc_typeck = { path = "../librustc_typeck" }
 syntax = { path = "../libsyntax" }

src/librustc_save_analysis/dump_visitor.rs

@@ -28,8 +28,9 @@
 use rustc::ty::{self, TyCtxt};
 use rustc_data_structures::fx::FxHashSet;
 
-use std::path::{Path, PathBuf};
+use std::path::Path;
 use std::env;
+use std::fs;
 
 use syntax::ast::{self, Attribute, NodeId, PatKind, CRATE_NODE_ID};
 use syntax::parse::token;
@@ -172,11 +173,20 @@ pub fn dump_crate_info(&mut self, name: &str, krate: &ast::Crate) {
         self.dumper.crate_prelude(data);
     }
 
-    pub fn dump_compilation_options(&mut self) {
-        // Apply possible `remap-path-prefix` remapping to the raw invocation
-        let invocation = {
+    pub fn dump_compilation_options(&mut self, crate_name: &str) {
+        // Apply possible `remap-path-prefix` remapping to the raw command
+        let command = {
+            let mapping = self.tcx.sess.source_map().path_mapping();
+            let remap_arg = |x: &str| -> String {
+                match fs::canonicalize(x) {
+                    Ok(path) => mapping.map_prefix(path).0.to_str().unwrap().to_owned(),
+                    Err(_) => x.to_owned(), // Probably not a path, ignore
+                }
+            };
+
             let remap_arg_indices = {
                 let mut indices = FxHashSet();
+                // rustc args are guaranteed to be valid UTF-8 (checked early)
                 for (i, e) in env::args().enumerate() {
                     if e.starts_with("--remap-path-prefix=") {
                         indices.insert(i);
@@ -188,19 +198,10 @@ pub fn dump_compilation_options(&mut self) {
                 indices
             };
 
-            let args_without_remap_args = env::args()
+            let args = env::args()
                 .enumerate()
                 .filter(|(i, _)| !remap_arg_indices.contains(i))
-                .map(|(_, e)| e);
-
-            let mapping = self.tcx.sess.source_map().path_mapping();
-            let remap_arg = |x: &str| -> String {
-                mapping.map_prefix(PathBuf::from(x)).0.to_str().unwrap().to_owned()
-            };
-
-            // Naively attempt to remap every argument
-            let args = args_without_remap_args
-                .map(|elem| {
+                .map(|(_, elem)| {
                     let mut arg = elem.splitn(2, '=');
                     match (arg.next(), arg.next()) {
                         // Apart from `--remap...`, in `a=b` args usually only
@@ -214,14 +215,10 @@ pub fn dump_compilation_options(&mut self) {
             args.as_slice().join(" ")
         };
 
-        let opts = &self.tcx.sess.opts;
-
         let data = CompilationOptions {
-            invocation,
-            crate_name: opts.crate_name.clone(),
-            test: opts.test,
-            sysroot: opts.maybe_sysroot.clone(),
-            target_triple: opts.target_triple.to_string(),
+            directory: self.tcx.sess.working_dir.0.clone(),
+            command,
+            output: self.save_ctxt.compilation_output(crate_name),
         };
 
         self.dumper.compilation_opts(data);

src/librustc_save_analysis/lib.rs

@@ -23,6 +23,7 @@
 #[macro_use]
 extern crate log;
 extern crate rustc_data_structures;
+extern crate rustc_codegen_utils;
 extern crate rustc_serialize;
 extern crate rustc_target;
 extern crate rustc_typeck;
@@ -45,9 +46,10 @@
 use rustc::hir::Node;
 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
 use rustc::middle::cstore::ExternCrate;
-use rustc::session::config::CrateType;
+use rustc::session::config::{CrateType, OutputType};
 use rustc::ty::{self, TyCtxt};
 use rustc_typeck::hir_ty_to_ty;
+use rustc_codegen_utils::link::{filename_for_metadata, out_filename};
 
 use std::cell::Cell;
 use std::default::Default;
@@ -111,6 +113,24 @@ fn span_from_span(&self, span: Span) -> SpanData {
         }
     }
 
+    // Returns path to the compilation output (e.g. libfoo-12345678.rmeta)
+    pub fn compilation_output(&self, crate_name: &str) -> PathBuf {
+        let sess = &self.tcx.sess;
+        // Save-analysis is emitted per whole session, not per each crate type
+        let crate_type = sess.crate_types.borrow()[0];
+        let outputs = &*self.tcx.output_filenames(LOCAL_CRATE);
+
+        if outputs.outputs.contains_key(&OutputType::Metadata) {
+            filename_for_metadata(sess, crate_name, outputs)
+        } else if outputs.outputs.should_codegen() {
+            out_filename(sess, crate_type, outputs, crate_name)
+        } else {
+            // Otherwise it's only a DepInfo, in which case we return early and
+            // not even reach the analysis stage.
+            unreachable!()
+        }
+    }
+
     // List external crates used by the current crate.
     pub fn get_external_crates(&self) -> Vec<ExternalCrateData> {
         let mut result = Vec::with_capacity(self.tcx.crates().len());
@@ -139,15 +159,9 @@ pub fn get_external_crates(&self) -> Vec<ExternalCrateData> {
                     disambiguator: self.tcx.crate_disambiguator(n).to_fingerprint().as_value(),
                 },
                 source: CrateSource {
-                    dylib: src.dylib.as_ref().map(|(ref path, _)|
-                        map_prefix(path).display().to_string()
-                    ),
-                    rlib: src.rlib.as_ref().map(|(ref path, _)|
-                        map_prefix(path).display().to_string()
-                    ),
-                    rmeta: src.rmeta.as_ref().map(|(ref path, _)|
-                        map_prefix(path).display().to_string()
-                    ),
+                    dylib: src.dylib.as_ref().map(|(path, _)| map_prefix(path)),
+                    rlib: src.rlib.as_ref().map(|(path, _)| map_prefix(path)),
+                    rmeta: src.rmeta.as_ref().map(|(path, _)| map_prefix(path)),
                 }
             });
         }
@@ -1103,7 +1117,7 @@ fn save<'l, 'tcx>(
         let mut visitor = DumpVisitor::new(save_ctxt, &mut dumper);
 
         visitor.dump_crate_info(cratename, krate);
-        visitor.dump_compilation_options();
+        visitor.dump_compilation_options(cratename);
         visit::walk_crate(&mut visitor, krate);
     }
 }
@@ -1129,7 +1143,7 @@ fn save<'l, 'tcx>(
         let mut visitor = DumpVisitor::new(save_ctxt, &mut dumper);
 
         visitor.dump_crate_info(cratename, krate);
-        visitor.dump_compilation_options();
+        visitor.dump_compilation_options(cratename);
         visit::walk_crate(&mut visitor, krate);
     }
 }