Auto merge of #150283 - Urgau:remap-debuginfo-absolute, r=jieyouxu

Remap both absolute and relative paths when building `rustc` and `std`

Turns out [#150110](#150110) didn't work as expected, because when the standard library sources are present, we [helpfully un-remap the paths](https://github.com/rust-lang/rust/blob/e951f470d76febcc6f0a5b409c509eb77450a336/compiler/rustc_metadata/src/rmeta/decoder.rs#L1656-L1702) to the local directory of the user, including when we are building the compiler and standard library it-self (duh!), and since those paths are absolute (not relative), our purely relative remapping didn't pick them up.

This behavior wasn't a issue before because the un-remap logic immediately tries to remap them again, and since we had the absolute remapping we would just remap them to the the same thing.

To fix that issue I've adjusted our remapping to remap both the absolute and relative paths when building `rustc` and `std`, as well as added a run-make to make sure we don't regress it again (with a new `needs-std-remap-debuginfo` directive).

r? `@jieyouxu`

Author: bors

src/bootstrap/src/bin/rustc.rs

@@ -168,8 +168,11 @@ fn main() {
         }
     }
 
-    if let Ok(map) = env::var("RUSTC_DEBUGINFO_MAP") {
-        cmd.arg("--remap-path-prefix").arg(&map);
+    // The remap flags for the compiler and standard library sources.
+    if let Ok(maps) = env::var("RUSTC_DEBUGINFO_MAP") {
+        for map in maps.split('\t') {
+            cmd.arg("--remap-path-prefix").arg(map);
+        }
     }
     // The remap flags for Cargo registry sources need to be passed after the remapping for the
     // Rust source code directory, to handle cases when $CARGO_HOME is inside the source directory.

src/bootstrap/src/core/build_steps/test.rs

@@ -2257,6 +2257,10 @@ Please disable assertions with `rust.debug-assertions = false`.
             cmd.arg("--with-std-debug-assertions");
         }
 
+        if builder.config.rust_remap_debuginfo {
+            cmd.arg("--with-std-remap-debuginfo");
+        }
+
         let mut llvm_components_passed = false;
         let mut copts_passed = false;
         if builder.config.llvm_enabled(test_compiler.host) {

src/bootstrap/src/core/builder/cargo.rs

@@ -1025,15 +1025,26 @@ impl Builder<'_> {
                 if let Some(ref map_to) =
                     self.build.debuginfo_map_to(GitRepo::Rustc, RemapScheme::NonCompiler)
                 {
+                    // Tell the compiler which prefix was used for remapping the standard library
                     cargo.env("CFG_VIRTUAL_RUST_SOURCE_BASE_DIR", map_to);
                 }
 
                 if let Some(ref map_to) =
                     self.build.debuginfo_map_to(GitRepo::Rustc, RemapScheme::Compiler)
                 {
-                    // When building compiler sources, we want to apply the compiler remap scheme.
-                    cargo.env("RUSTC_DEBUGINFO_MAP", format!("compiler/={map_to}/compiler"));
+                    // Tell the compiler which prefix was used for remapping the compiler it-self
                     cargo.env("CFG_VIRTUAL_RUSTC_DEV_SOURCE_BASE_DIR", map_to);
+
+                    // When building compiler sources, we want to apply the compiler remap scheme.
+                    let map = [
+                        // Cargo use relative paths for workspace members, so let's remap those.
+                        format!("compiler/={map_to}/compiler"),
+                        // rustc creates absolute paths (in part bc of the `rust-src` unremap
+                        // and for working directory) so let's remap the build directory as well.
+                        format!("{}={map_to}", self.build.src.display()),
+                    ]
+                    .join("\t");
+                    cargo.env("RUSTC_DEBUGINFO_MAP", map);
                 }
             }
             Mode::Std
@@ -1044,7 +1055,16 @@ impl Builder<'_> {
                 if let Some(ref map_to) =
                     self.build.debuginfo_map_to(GitRepo::Rustc, RemapScheme::NonCompiler)
                 {
-                    cargo.env("RUSTC_DEBUGINFO_MAP", format!("library/={map_to}/library"));
+                    // When building the standard library sources, we want to apply the std remap scheme.
+                    let map = [
+                        // Cargo use relative paths for workspace members, so let's remap those.
+                        format!("library/={map_to}/library"),
+                        // rustc creates absolute paths (in part bc of the `rust-src` unremap
+                        // and for working directory) so let's remap the build directory as well.
+                        format!("{}={map_to}", self.build.src.display()),
+                    ]
+                    .join("\t");
+                    cargo.env("RUSTC_DEBUGINFO_MAP", map);
                 }
             }
         }

src/doc/rustc-dev-guide/src/tests/directives.md

@@ -189,6 +189,10 @@ settings:
   assertions.
 - `needs-std-debug-assertions` — ignores if std was not built with debug
   assertions.
+- `ignore-std-remap-debuginfo` — ignores if std was built with remapping of
+  it's sources.
+- `needs-std-remap-debugino` — ignores if std was not built with remapping of
+  it's sources.
 - `ignore-rustc-debug-assertions` — ignores if rustc was built with debug
   assertions.
 - `needs-rustc-debug-assertions` — ignores if rustc was not built with debug

src/tools/compiletest/src/common.rs

@@ -438,6 +438,11 @@ pub struct Config {
     /// FIXME: make it clearer that this refers to the staged `std`, not stage 0 `std`.
     pub with_std_debug_assertions: bool,
 
+    /// Whether *staged* `std` was built with remapping of debuginfo.
+    ///
+    /// FIXME: make it clearer that this refers to the staged `std`, not stage 0 `std`.
+    pub with_std_remap_debuginfo: bool,
+
     /// Only run tests that match these filters (using `libtest` "test name contains" filter logic).
     ///
     /// FIXME(#139660): the current hand-rolled test executor intentionally mimics the `libtest`

src/tools/compiletest/src/directives/cfg.rs

@@ -202,6 +202,11 @@ pub(crate) fn prepare_conditions(config: &Config) -> PreparedConditions {
         config.with_std_debug_assertions,
         "when std is built with debug assertions",
     );
+    builder.cond(
+        "std-remap-debuginfo",
+        config.with_std_remap_debuginfo,
+        "when std is built with remapping of debuginfo",
+    );
 
     for &debugger in Debugger::STR_VARIANTS {
         builder.cond(

src/tools/compiletest/src/directives/directive_names.rs

@@ -184,6 +184,7 @@ pub(crate) const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "needs-sanitizer-support",
     "needs-sanitizer-thread",
     "needs-std-debug-assertions",
+    "needs-std-remap-debuginfo",
     "needs-subprocess",
     "needs-symlink",
     "needs-target-has-atomic",

src/tools/compiletest/src/directives/needs.rs

@@ -181,6 +181,11 @@ pub(super) fn handle_needs(
             condition: config.with_std_debug_assertions,
             ignore_reason: "ignored if std wasn't built with debug assertions",
         },
+        Need {
+            name: "needs-std-remap-debuginfo",
+            condition: config.with_std_remap_debuginfo,
+            ignore_reason: "ignored if std wasn't built with remapping of debuginfo",
+        },
         Need {
             name: "needs-target-std",
             condition: build_helper::targets::target_supports_std(&config.target),

src/tools/compiletest/src/directives/tests.rs

@@ -117,6 +117,7 @@ struct ConfigBuilder {
     profiler_runtime: bool,
     rustc_debug_assertions: bool,
     std_debug_assertions: bool,
+    std_remap_debuginfo: bool,
 }
 
 impl ConfigBuilder {
@@ -185,6 +186,11 @@ impl ConfigBuilder {
         self
     }
 
+    fn std_remap_debuginfo(&mut self, is_enabled: bool) -> &mut Self {
+        self.std_remap_debuginfo = is_enabled;
+        self
+    }
+
     fn build(&mut self) -> Config {
         let args = &[
             "compiletest",
@@ -246,6 +252,9 @@ impl ConfigBuilder {
         if self.std_debug_assertions {
             args.push("--with-std-debug-assertions".to_owned());
         }
+        if self.std_remap_debuginfo {
+            args.push("--with-std-remap-debuginfo".to_owned());
+        }
 
         args.push("--rustc-path".to_string());
         args.push(std::env::var("TEST_RUSTC").expect("must be configured by bootstrap"));
@@ -400,6 +409,19 @@ fn std_debug_assertions() {
     assert!(check_ignore(&config, "//@ ignore-std-debug-assertions"));
 }
 
+#[test]
+fn std_remap_debuginfo() {
+    let config: Config = cfg().std_remap_debuginfo(false).build();
+
+    assert!(check_ignore(&config, "//@ needs-std-remap-debuginfo"));
+    assert!(!check_ignore(&config, "//@ ignore-std-remap-debuginfo"));
+
+    let config: Config = cfg().std_remap_debuginfo(true).build();
+
+    assert!(!check_ignore(&config, "//@ needs-std-remap-debuginfo"));
+    assert!(check_ignore(&config, "//@ ignore-std-remap-debuginfo"));
+}
+
 #[test]
 fn stage() {
     let config: Config = cfg().stage(1).stage_id("stage1-x86_64-unknown-linux-gnu").build();

src/tools/compiletest/src/lib.rs

@@ -106,6 +106,7 @@ fn parse_config(args: Vec<String>) -> Config {
         .optflag("", "has-enzyme", "run tests that require enzyme")
         .optflag("", "with-rustc-debug-assertions", "whether rustc was built with debug assertions")
         .optflag("", "with-std-debug-assertions", "whether std was built with debug assertions")
+        .optflag("", "with-std-remap-debuginfo", "whether std was built with remapping")
         .optmulti(
             "",
             "skip",
@@ -295,6 +296,7 @@ fn parse_config(args: Vec<String>) -> Config {
     let run_ignored = matches.opt_present("ignored");
     let with_rustc_debug_assertions = matches.opt_present("with-rustc-debug-assertions");
     let with_std_debug_assertions = matches.opt_present("with-std-debug-assertions");
+    let with_std_remap_debuginfo = matches.opt_present("with-std-remap-debuginfo");
     let mode = matches.opt_str("mode").unwrap().parse().expect("invalid mode");
     let has_enzyme = matches.opt_present("has-enzyme");
     let filters = if mode == TestMode::RunMake {
@@ -402,6 +404,7 @@ fn parse_config(args: Vec<String>) -> Config {
         run_ignored,
         with_rustc_debug_assertions,
         with_std_debug_assertions,
+        with_std_remap_debuginfo,
         filters,
         skip: matches.opt_strs("skip"),
         filter_exact: matches.opt_present("exact"),