Rollup merge of #115869 - ferrocene:pa-fix-tests-cargo-remap, r=compiler-errors

Avoid blessing cargo deps's source code in ui tests

Before this PR, the source code of dependencies was included in UI test error messages whenever possible. Unfortunately, "whenever possible" means in some cases the source code wouldn't be injected, resulting in a test failure.

One such case is when `$CARGO_HOME` is remapped to something that is not present on disk [^1]. As the remapped path doesn't exist on disk, the source code wouldn't be showed in `tests/ui/issues/issue-21763.rs`:

```diff
    = note: required for `hashbrown::raw::RawTable<(Rc<()>, Rc<()>)>` to implement `Send`
 note: required because it appears within the type `HashMap<Rc<()>, Rc<()>, RandomState>`
   --> $HASHBROWN_SRC_LOCATION
-   |
-LL | pub struct HashMap<K, V, S = DefaultHashBuilder, A: Allocator + Clone = Global> {
-   |            ^^^^^^^
 note: required because it appears within the type `HashMap<Rc<()>, Rc<()>>`
   --> $SRC_DIR/std/src/collections/hash/map.rs:LL:COL
 note: required by a bound in `foo`
```

This PR fixes the problem by always hiding dependencies source code in the error messages generated during UI tests. This is implemented with a new internal flag, `-Z ignore-directory-in-diagnostics-source-blocks=$path`, which compiletest passes during UI tests. Once this is merged, remapping the Cargo home will be supported.

This PR is best reviewed commit-by-commit.

[^1]: After being puzzled for a bit, I discovered why this never impacted `rust-lang/rust`: we don't remap `$CARGO_HOME` :sweat_smile:. Instead, we set `$CARGO_HOME` to `/cargo` in CI, which sort-of-but-not-really achieves the same effect.

9 files changed, 69 insertions, 10 deletions

diff --git a/Cargo.lock b/Cargo.lock
index fe4118db1b7..a93078829e2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -662,6 +662,7 @@ dependencies = [
  "diff",
  "getopts",
  "glob",
+ "home",
  "lazycell",
  "libc",
  "miow",
@@ -1664,6 +1665,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
 [[package]]
+name = "home"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5444c27eef6923071f7ebcc33e3444508466a76f7a2b93da00ed6e19f30c1ddb"
+dependencies = [
+ "windows-sys 0.48.0",
+]
+
+[[package]]
 name = "html-checker"
 version = "0.1.0"
 dependencies = [
diff --git a/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs b/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
index 5d3b2f45166..203e529120b 100644
--- a/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
+++ b/compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs
@@ -169,6 +169,7 @@ impl AnnotateSnippetEmitterWriter {
                         .map(|line| {
                             // Ensure the source file is present before we try
                             // to load a string from it.
+                            // FIXME(#115869): support -Z ignore-directory-in-diagnostics-source-blocks
                             source_map.ensure_source_file_source_present(&file);
                             (
                                 format!("{}", source_map.filename_for_diagnostics(&file.name)),
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 58be74f887b..d322cbe9d9b 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -8,7 +8,7 @@
 //! The output types are defined in `rustc_session::config::ErrorOutputType`.
 
 use rustc_span::source_map::SourceMap;
-use rustc_span::{FileLines, SourceFile, Span};
+use rustc_span::{FileLines, FileName, SourceFile, Span};
 
 use crate::snippet::{
     Annotation, AnnotationColumn, AnnotationType, Line, MultilineAnnotation, Style, StyledString,
@@ -635,6 +635,7 @@ pub struct EmitterWriter {
     short_message: bool,
     teach: bool,
     ui_testing: bool,
+    ignored_directories_in_source_blocks: Vec<String>,
     diagnostic_width: Option<usize>,
 
     macro_backtrace: bool,
@@ -664,6 +665,7 @@ impl EmitterWriter {
             short_message: false,
             teach: false,
             ui_testing: false,
+            ignored_directories_in_source_blocks: Vec::new(),
             diagnostic_width: None,
             macro_backtrace: false,
             track_diagnostics: false,
@@ -1193,7 +1195,7 @@ impl EmitterWriter {
         let will_be_emitted = |span: Span| {
             !span.is_dummy() && {
                 let file = sm.lookup_source_file(span.hi());
-                sm.ensure_source_file_source_present(&file)
+                should_show_source_code(&self.ignored_directories_in_source_blocks, sm, &file)
             }
         };
 
@@ -1388,7 +1390,11 @@ impl EmitterWriter {
         // Print out the annotate source lines that correspond with the error
         for annotated_file in annotated_files {
             // we can't annotate anything if the source is unavailable.
-            if !sm.ensure_source_file_source_present(&annotated_file.file) {
+            if !should_show_source_code(
+                &self.ignored_directories_in_source_blocks,
+                sm,
+                &annotated_file.file,
+            ) {
                 if !self.short_message {
                     // We'll just print an unannotated message.
                     for (annotation_id, line) in annotated_file.lines.iter().enumerate() {
@@ -2737,3 +2743,18 @@ pub fn is_case_difference(sm: &SourceMap, suggested: &str, sp: Span) -> bool {
             //        bug, but be defensive against that here.
             && found != suggested
 }
+
+pub(crate) fn should_show_source_code(
+    ignored_directories: &[String],
+    sm: &SourceMap,
+    file: &SourceFile,
+) -> bool {
+    if !sm.ensure_source_file_source_present(file) {
+        return false;
+    }
+
+    let FileName::Real(name) = &file.name else { return true };
+    name.local_path()
+        .map(|path| ignored_directories.iter().all(|dir| !path.starts_with(dir)))
+        .unwrap_or(true)
+}
diff --git a/compiler/rustc_errors/src/json.rs b/compiler/rustc_errors/src/json.rs
index 38667c5ff81..0cb75c71b73 100644
--- a/compiler/rustc_errors/src/json.rs
+++ b/compiler/rustc_errors/src/json.rs
@@ -12,7 +12,7 @@
 use rustc_span::source_map::{FilePathMapping, SourceMap};
 use termcolor::{ColorSpec, WriteColor};
 
-use crate::emitter::{Emitter, HumanReadableErrorType};
+use crate::emitter::{should_show_source_code, Emitter, HumanReadableErrorType};
 use crate::registry::Registry;
 use crate::translation::{to_fluent_args, Translate};
 use crate::DiagnosticId;
@@ -45,6 +45,7 @@ pub struct JsonEmitter {
     fallback_bundle: LazyFallbackBundle,
     pretty: bool,
     ui_testing: bool,
+    ignored_directories_in_source_blocks: Vec<String>,
     json_rendered: HumanReadableErrorType,
     diagnostic_width: Option<usize>,
     macro_backtrace: bool,
@@ -73,6 +74,7 @@ impl JsonEmitter {
             fallback_bundle,
             pretty,
             ui_testing: false,
+            ignored_directories_in_source_blocks: Vec::new(),
             json_rendered,
             diagnostic_width,
             macro_backtrace,
@@ -127,6 +129,7 @@ impl JsonEmitter {
             fallback_bundle,
             pretty,
             ui_testing: false,
+            ignored_directories_in_source_blocks: Vec::new(),
             json_rendered,
             diagnostic_width,
             macro_backtrace,
@@ -138,6 +141,10 @@ impl JsonEmitter {
     pub fn ui_testing(self, ui_testing: bool) -> Self {
         Self { ui_testing, ..self }
     }
+
+    pub fn ignored_directories_in_source_blocks(self, value: Vec<String>) -> Self {
+        Self { ignored_directories_in_source_blocks: value, ..self }
+    }
 }
 
 impl Translate for JsonEmitter {
@@ -381,6 +388,7 @@ impl Diagnostic {
             .track_diagnostics(je.track_diagnostics)
             .terminal_url(je.terminal_url)
             .ui_testing(je.ui_testing)
+            .ignored_directories_in_source_blocks(je.ignored_directories_in_source_blocks.clone())
             .emit_diagnostic(diag);
         let output = Arc::try_unwrap(output.0).unwrap().into_inner().unwrap();
         let output = String::from_utf8(output).unwrap();
@@ -558,7 +566,11 @@ impl DiagnosticSpanLine {
             .span_to_lines(span)
             .map(|lines| {
                 // We can't get any lines if the source is unavailable.
-                if !je.sm.ensure_source_file_source_present(&lines.file) {
+                if !should_show_source_code(
+                    &je.ignored_directories_in_source_blocks,
+                    &je.sm,
+                    &lines.file,
+                ) {
                     return vec![];
                 }
 
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 73fd7965895..f2c8f0bc198 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -1536,6 +1536,8 @@ options! {
         "generate human-readable, predictable names for codegen units (default: no)"),
     identify_regions: bool = (false, parse_bool, [UNTRACKED],
         "display unnamed regions as `'<id>`, using a non-ident unique id (default: no)"),
+    ignore_directory_in_diagnostics_source_blocks: Vec<String> = (Vec::new(), parse_string_push, [UNTRACKED],
+        "do not display the source code block in diagnostics for files in the directory"),
     incremental_ignore_spans: bool = (false, parse_bool, [TRACKED],
         "ignore spans during ICH computation -- used for testing (default: no)"),
     incremental_info: bool = (false, parse_bool, [UNTRACKED],
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 9bff9017881..86f4e7b48da 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -1295,7 +1295,10 @@ fn default_emitter(
                     .diagnostic_width(sopts.diagnostic_width)
                     .macro_backtrace(macro_backtrace)
                     .track_diagnostics(track_diagnostics)
-                    .terminal_url(terminal_url);
+                    .terminal_url(terminal_url)
+                    .ignored_directories_in_source_blocks(
+                        sopts.unstable_opts.ignore_directory_in_diagnostics_source_blocks.clone(),
+                    );
                 Box::new(emitter.ui_testing(sopts.unstable_opts.ui_testing))
             }
         }
@@ -1312,7 +1315,10 @@ fn default_emitter(
                 track_diagnostics,
                 terminal_url,
             )
-            .ui_testing(sopts.unstable_opts.ui_testing),
+            .ui_testing(sopts.unstable_opts.ui_testing)
+            .ignored_directories_in_source_blocks(
+                sopts.unstable_opts.ignore_directory_in_diagnostics_source_blocks.clone(),
+            ),
         ),
     }
 }
diff --git a/src/tools/compiletest/Cargo.toml b/src/tools/compiletest/Cargo.toml
index ff1d5cecb72..bb1fa6e9237 100644
--- a/src/tools/compiletest/Cargo.toml
+++ b/src/tools/compiletest/Cargo.toml
@@ -24,6 +24,7 @@ walkdir = "2"
 glob = "0.3.0"
 lazycell = "1.3.0"
 anyhow = "1"
+home = "0.5.5"
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 65af650f6e5..855df427538 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -2335,6 +2335,15 @@ impl<'test> TestCx<'test> {
         rustc.arg("-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX");
         rustc.arg("-Ztranslate-remapped-path-to-local-path=no");
 
+        // Hide Cargo dependency sources from ui tests to make sure the error message doesn't
+        // change depending on whether $CARGO_HOME is remapped or not. If this is not present,
+        // when $CARGO_HOME is remapped the source won't be shown, and when it's not remapped the
+        // source will be shown, causing a blessing hell.
+        rustc.arg("-Z").arg(format!(
+            "ignore-directory-in-diagnostics-source-blocks={}",
+            home::cargo_home().expect("failed to find cargo home").to_str().unwrap()
+        ));
+
         // Optionally prevent default --sysroot if specified in test compile-flags.
         if !self.props.compile_flags.iter().any(|flag| flag.starts_with("--sysroot"))
             && !self.config.host_rustcflags.iter().any(|flag| flag == "--sysroot")
diff --git a/tests/ui/issues/issue-21763.stderr b/tests/ui/issues/issue-21763.stderr
index df50118ac47..a887635d354 100644
--- a/tests/ui/issues/issue-21763.stderr
+++ b/tests/ui/issues/issue-21763.stderr
@@ -9,9 +9,6 @@ LL |     foo::<HashMap<Rc<()>, Rc<()>>>();
    = note: required for `hashbrown::raw::RawTable<(Rc<()>, Rc<()>)>` to implement `Send`
 note: required because it appears within the type `HashMap<Rc<()>, Rc<()>, RandomState>`
   --> $HASHBROWN_SRC_LOCATION
-   |
-LL | pub struct HashMap<K, V, S = DefaultHashBuilder, A: Allocator + Clone = Global> {
-   |            ^^^^^^^
 note: required because it appears within the type `HashMap<Rc<()>, Rc<()>>`
   --> $SRC_DIR/std/src/collections/hash/map.rs:LL:COL
 note: required by a bound in `foo`