rust-lang · matthiaskrgr · Dec 23, 2024 · Dec 26, 2024 · Jan 21, 2025 · Jan 21, 2025
diff --git a/compiler/rustc_borrowck/src/polonius/dump.rs b/compiler/rustc_borrowck/src/polonius/dump.rs
@@ -1,7 +1,9 @@
 use std::io;
 
-use rustc_middle::mir::pretty::{PrettyPrintMirOptions, dump_mir_with_options};
-use rustc_middle::mir::{Body, ClosureRegionRequirements, PassWhere};
+use rustc_middle::mir::pretty::{
+    PassWhere, PrettyPrintMirOptions, create_dump_file, dump_enabled, dump_mir_to_writer,
+};
+use rustc_middle::mir::{Body, ClosureRegionRequirements};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::MirIncludeSpans;
 
@@ -10,9 +12,6 @@ use crate::polonius::{LocalizedOutlivesConstraint, LocalizedOutlivesConstraintSe
 use crate::{BorrowckInferCtxt, RegionInferenceContext};
 
 /// `-Zdump-mir=polonius` dumps MIR annotated with NLL and polonius specific information.
-// Note: this currently duplicates most of NLL MIR, with some additions for the localized outlives
-// constraints. This is ok for now as this dump will change in the near future to an HTML file to
-// become more useful.
 pub(crate) fn dump_polonius_mir<'tcx>(
     infcx: &BorrowckInferCtxt<'tcx>,
     body: &Body<'tcx>,
@@ -26,25 +25,113 @@ pub(crate) fn dump_polonius_mir<'tcx>(
         return;
     }
 
+    if !dump_enabled(tcx, "polonius", body.source.def_id()) {
+        return;
+    }
+
     let localized_outlives_constraints = localized_outlives_constraints
         .expect("missing localized constraints with `-Zpolonius=next`");
 
-    // We want the NLL extra comments printed by default in NLL MIR dumps (they were removed in
-    // #112346). Specifying `-Z mir-include-spans` on the CLI still has priority: for example,
-    // they're always disabled in mir-opt tests to make working with blessed dumps easier.
+    let _: io::Result<()> = try {
+        let mut file = create_dump_file(tcx, "html", false, "polonius", &0, body)?;
+        emit_polonius_dump(
+            tcx,
+            body,
+            regioncx,
+            borrow_set,
+            localized_outlives_constraints,
+            closure_region_requirements,
+            &mut file,
+        )?;
+    };
+}
+
+/// The polonius dump consists of:
+/// - the NLL MIR
+/// - the list of polonius localized constraints
+/// - a mermaid graph of the CFG
+fn emit_polonius_dump<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    body: &Body<'tcx>,
+    regioncx: &RegionInferenceContext<'tcx>,
+    borrow_set: &BorrowSet<'tcx>,
+    localized_outlives_constraints: LocalizedOutlivesConstraintSet,
+    closure_region_requirements: &Option<ClosureRegionRequirements<'tcx>>,
+    out: &mut dyn io::Write,
+) -> io::Result<()> {
+    // Prepare the HTML dump file prologue.
+    writeln!(out, "<!DOCTYPE html>")?;
+    writeln!(out, "<html>")?;
+    writeln!(out, "<head><title>Polonius MIR dump</title></head>")?;
+    writeln!(out, "<body>")?;
+
+    // Section 1: the NLL + Polonius MIR.
+    writeln!(out, "<div>")?;
+    writeln!(out, "Raw MIR dump")?;
+    writeln!(out, "<code><pre>")?;
+    emit_html_mir(
+        tcx,
+        body,
+        regioncx,
+        borrow_set,
+        localized_outlives_constraints,
+        closure_region_requirements,
+        out,
+    )?;
+    writeln!(out, "</pre></code>")?;
+    writeln!(out, "</div>")?;
+
+    // Section 2: mermaid visualization of the CFG.
+    writeln!(out, "<div>")?;
+    writeln!(out, "Control-flow graph")?;
+    writeln!(out, "<code><pre class='mermaid'>")?;
+    emit_mermaid_cfg(body, out)?;
+    writeln!(out, "</pre></code>")?;
+    writeln!(out, "</div>")?;
+
+    // Finalize the dump with the HTML epilogue.
+    writeln!(
+        out,
+        "<script src='https://cdn.jsdelivr.net/npm/mermaid/dist/mermaid.min.js'></script>"
+    )?;
+    writeln!(out, "<script>")?;
+    writeln!(out, "mermaid.initialize({{ startOnLoad: false, maxEdges: 100 }});")?;
+    writeln!(out, "mermaid.run({{ querySelector: '.mermaid' }})")?;
+    writeln!(out, "</script>")?;
+    writeln!(out, "</body>")?;
+    writeln!(out, "</html>")?;
+
+    Ok(())
+}
+
+/// Emits the polonius MIR, as escaped HTML.
+fn emit_html_mir<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    body: &Body<'tcx>,
+    regioncx: &RegionInferenceContext<'tcx>,
+    borrow_set: &BorrowSet<'tcx>,
+    localized_outlives_constraints: LocalizedOutlivesConstraintSet,
+    closure_region_requirements: &Option<ClosureRegionRequirements<'tcx>>,
+    out: &mut dyn io::Write,
+) -> io::Result<()> {
+    // Buffer the regular MIR dump to be able to escape it.
+    let mut buffer = Vec::new();
+
+    // We want the NLL extra comments printed by default in NLL MIR dumps. Specifying `-Z
+    // mir-include-spans` on the CLI still has priority.
     let options = PrettyPrintMirOptions {
         include_extra_comments: matches!(
             tcx.sess.opts.unstable_opts.mir_include_spans,
             MirIncludeSpans::On | MirIncludeSpans::Nll
         ),
     };
 
-    dump_mir_with_options(
+    dump_mir_to_writer(
         tcx,
-        false,
         "polonius",
         &0,
         body,
+        &mut buffer,
         |pass_where, out| {
             emit_polonius_mir(
                 tcx,
@@ -57,7 +144,27 @@ pub(crate) fn dump_polonius_mir<'tcx>(
             )
         },
         options,
-    );
+    )?;
+
+    // Escape the handful of characters that need it. We don't need to be particularly efficient:
+    // we're actually writing into a buffered writer already. Note that MIR dumps are valid UTF-8.
+    let buffer = String::from_utf8_lossy(&buffer);
+    for ch in buffer.chars() {
+        let escaped = match ch {
+            '>' => "&gt;",
+            '<' => "&lt;",
+            '&' => "&amp;",
+            '\'' => "&#39;",
+            '"' => "&quot;",
+            _ => {
+                // The common case, no escaping needed.
+                write!(out, "{}", ch)?;
+                continue;
+            }
+        };
+        write!(out, "{}", escaped)?;
+    }
+    Ok(())
 }
 
 /// Produces the actual NLL + Polonius MIR sections to emit during the dumping process.
@@ -102,3 +209,55 @@ fn emit_polonius_mir<'tcx>(
 
     Ok(())
 }
+
+/// Emits a mermaid flowchart of the CFG blocks and edges, similar to the graphviz version.
+fn emit_mermaid_cfg(body: &Body<'_>, out: &mut dyn io::Write) -> io::Result<()> {
+    use rustc_middle::mir::{TerminatorEdges, TerminatorKind};
+
+    // The mermaid chart type: a top-down flowchart.
+    writeln!(out, "flowchart TD")?;
+
+    // Emit the block nodes.
+    for (block_idx, block) in body.basic_blocks.iter_enumerated() {
+        let block_idx = block_idx.as_usize();
+        let cleanup = if block.is_cleanup { " (cleanup)" } else { "" };
+        writeln!(out, "{block_idx}[\"bb{block_idx}{cleanup}\"]")?;
+    }
+
+    // Emit the edges between blocks, from the terminator edges.
+    for (block_idx, block) in body.basic_blocks.iter_enumerated() {
+        let block_idx = block_idx.as_usize();
+        let terminator = block.terminator();
+        match terminator.edges() {
+            TerminatorEdges::None => {}
+            TerminatorEdges::Single(bb) => {
+                writeln!(out, "{block_idx} --> {}", bb.as_usize())?;
+            }
+            TerminatorEdges::Double(bb1, bb2) => {
+                if matches!(terminator.kind, TerminatorKind::FalseEdge { .. }) {
+                    writeln!(out, "{block_idx} --> {}", bb1.as_usize())?;
+                    writeln!(out, "{block_idx} -- imaginary --> {}", bb2.as_usize())?;
+                } else {
+                    writeln!(out, "{block_idx} --> {}", bb1.as_usize())?;
+                    writeln!(out, "{block_idx} -- unwind --> {}", bb2.as_usize())?;
+                }
+            }
+            TerminatorEdges::AssignOnReturn { return_, cleanup, .. } => {
+                for to_idx in return_ {
+                    writeln!(out, "{block_idx} --> {}", to_idx.as_usize())?;
+                }
+
+                if let Some(to_idx) = cleanup {
+                    writeln!(out, "{block_idx} -- unwind --> {}", to_idx.as_usize())?;
+                }
+            }
+            TerminatorEdges::SwitchInt { targets, .. } => {
+                for to_idx in targets.all_targets() {
+                    writeln!(out, "{block_idx} --> {}", to_idx.as_usize())?;
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
@@ -976,6 +976,3 @@ lint_uses_power_alignment = repr(C) does not follow the power alignment rule. Th
 
 lint_variant_size_differences =
     enum variant is more than three times larger ({$largest} bytes) than the next largest
-
-lint_wasm_c_abi =
-    older versions of the `wasm-bindgen` crate will be incompatible with future versions of Rust; please update to `wasm-bindgen` v0.2.88
diff --git a/compiler/rustc_lint/src/early/diagnostics.rs b/compiler/rustc_lint/src/early/diagnostics.rs
@@ -430,7 +430,6 @@ pub(super) fn decorate_lint(
         BuiltinLintDiag::UnusedCrateDependency { extern_crate, local_crate } => {
             lints::UnusedCrateDependency { extern_crate, local_crate }.decorate_lint(diag)
         }
-        BuiltinLintDiag::WasmCAbi => lints::WasmCAbi.decorate_lint(diag),
         BuiltinLintDiag::IllFormedAttributeInput { suggestions } => {
             lints::IllFormedAttributeInput {
                 num_suggestions: suggestions.len(),

diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
@@ -2566,10 +2566,6 @@ pub(crate) struct UnusedCrateDependency {
     pub local_crate: Symbol,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(lint_wasm_c_abi)]
-pub(crate) struct WasmCAbi;
-
 #[derive(LintDiagnostic)]
 #[diag(lint_ill_formed_attribute_input)]
 pub(crate) struct IllFormedAttributeInput {

diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
@@ -143,7 +143,6 @@ declare_lint_pass! {
         UNUSED_VARIABLES,
         USELESS_DEPRECATED,
         WARNINGS,
-        WASM_C_ABI,
         // tidy-alphabetical-end
     ]
 }
@@ -4647,44 +4646,6 @@ declare_lint! {
     };
 }
 
-declare_lint! {
-    /// The `wasm_c_abi` lint detects crate dependencies that are incompatible
-    /// with future versions of Rust that will emit spec-compliant C ABI.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,ignore (needs extern crate)
-    /// #![deny(wasm_c_abi)]
-    /// ```
-    ///
-    /// This will produce:
-    ///
-    /// ```text
-    /// error: the following packages contain code that will be rejected by a future version of Rust: wasm-bindgen v0.2.87
-    ///   |
-    /// note: the lint level is defined here
-    ///  --> src/lib.rs:1:9
-    ///   |
-    /// 1 | #![deny(wasm_c_abi)]
-    ///   |         ^^^^^^^^^^
-    /// ```
-    ///
-    /// ### Explanation
-    ///
-    /// Rust has historically emitted non-spec-compliant C ABI. This has caused
-    /// incompatibilities between other compilers and Wasm targets. In a future
-    /// version of Rust this will be fixed and therefore dependencies relying
-    /// on the non-spec-compliant C ABI will stop functioning.
-    pub WASM_C_ABI,
-    Deny,
-    "detects dependencies that are incompatible with the Wasm C ABI",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorReportInDeps,
-        reference: "issue #71871 <https://github.com/rust-lang/rust/issues/71871>",
-    };
-    crate_level_only
-}
-
 declare_lint! {
     /// The `uncovered_param_in_projection` lint detects a violation of one of Rust's orphan rules for
     /// foreign trait implementations that concerns the use of type parameters inside trait associated

diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
@@ -783,7 +783,6 @@ pub enum BuiltinLintDiag {
         extern_crate: Symbol,
         local_crate: Symbol,
     },
-    WasmCAbi,
     IllFormedAttributeInput {
         suggestions: Vec<String>,
     },

diff --git a/compiler/rustc_metadata/messages.ftl b/compiler/rustc_metadata/messages.ftl
@@ -290,6 +290,9 @@ metadata_unsupported_abi =
 metadata_unsupported_abi_i686 =
     ABI not supported by `#[link(kind = "raw-dylib")]` on i686
 
+metadata_wasm_c_abi =
+    older versions of the `wasm-bindgen` crate are incompatible with current versions of Rust; please update to `wasm-bindgen` v0.2.88
+
 metadata_wasm_import_form =
     wasm import module must be of the form `wasm_import_module = "string"`
 

diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
@@ -1076,12 +1076,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
             // Make a point span rather than covering the whole file
             let span = krate.spans.inner_span.shrink_to_lo();
 
-            self.sess.psess.buffer_lint(
-                lint::builtin::WASM_C_ABI,
-                span,
-                ast::CRATE_NODE_ID,
-                BuiltinLintDiag::WasmCAbi,
-            );
+            self.sess.dcx().emit_err(errors::WasmCAbi { span });
         }
     }
 

diff --git a/compiler/rustc_metadata/src/errors.rs b/compiler/rustc_metadata/src/errors.rs
@@ -732,3 +732,10 @@ pub struct ImportNameTypeRaw {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(metadata_wasm_c_abi)]
+pub(crate) struct WasmCAbi {
+    #[primary_span]
+    pub span: Span,
+}