[Debuginfo] improve enum value formatting in LLDB for better readability #145218

nilptr · 2025-08-10T16:02:45Z

TL;DR: When debugging with CodeLLDB, I noticed enum values were often hard to read because LLDB lists every possible variant, resulting in a verbose and cluttered view, even though only one variant is actually valid. Interestingly, raw enum types display nicely. After some investigation, I found that &enum values get classified as Other, so it falls back to DefaultSyntheticProvider, which causes this verbose output.

What does this PR do?

This PR contains 2 commits:

change the enum value formatting from showing 2 separate fields (value for attached data and $discr$ for the discriminator) to a concise <readable variant name>: <attached data> format
dereference pointer types in classify_rust_type so that it can return more accurate type for reference type

Self-test proof

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After:

rustbot · 2025-08-10T16:02:50Z

r? @Mark-Simulacrum

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rustbot · 2025-08-17T13:15:39Z

This PR was rebased onto a different master commit! Check out the changes with our range-diff.

Mark-Simulacrum · 2025-08-22T13:08:27Z

@bors r+

bors · 2025-08-22T13:08:30Z

📌 Commit 6be749b has been approved by Mark-Simulacrum

It is now in the queue for this repository.

…y-printer, r=Mark-Simulacrum [Debuginfo] improve enum value formatting in LLDB for better readability > TL;DR: When debugging with CodeLLDB, I noticed enum values were often hard to read because LLDB lists every possible variant, resulting in a verbose and cluttered view, even though only one variant is actually valid. Interestingly, raw enum types display nicely. After some investigation, I found that `&enum` values get classified as `Other`, so it falls back to `DefaultSyntheticProvider`, which causes this verbose output. ## What does this PR do? This PR contains 2 commits: 1. change the enum value formatting from showing 2 separate fields (`value` for attached data and `$discr$` for the discriminator) to a concise `<readable variant name>: <attached data>` format 2. dereference pointer types in `classify_rust_type` so that it can return more accurate type for reference type ## Self-test proof Before: <img width="1706" height="799" alt="before" src="https://github.com/user-attachments/assets/b66c7e22-990a-4da5-9036-34e3f9f62367" /> After: <img width="1541" height="678" alt="after" src="https://github.com/user-attachments/assets/36db32e2-f822-4883-8f17-cb8067e509f6" />

Rollup of 20 pull requests Successful merges: - #132087 (Fix overly restrictive lifetime in `core::panic::Location::file` return type) - #137396 (Recover `param: Ty = EXPR`) - #142185 (Convert moves of references to copies in ReferencePropagation) - #144443 (Make target pointer width in target json an integer) - #144648 (Implementation: `#[feature(nonpoison_rwlock)]`) - #144897 (print raw lifetime idents with r#) - #145218 ([Debuginfo] improve enum value formatting in LLDB for better readability) - #145380 (Add codegen-llvm regression tests) - #145573 (Add an experimental unsafe(force_target_feature) attribute.) - #145597 (resolve: Remove `ScopeSet::Late`) - #145641 (On E0277, point at type that doesn't implement bound) - #145669 (rustdoc-search: GUI tests check for `//` in URL) - #145695 (Introduce ProjectionElem::try_map.) - #145710 (Fix the ABI parameter inconsistency issue in debug.rs for LoongArch64) - #145726 (Experiment: Reborrow trait) - #145731 (Make raw pointers work in type-based search) - #145736 (triagebot: Update style team reviewers) - #145738 (Uplift rustc_mir_transform::coverage::counters::union_find to rustc_data_structures.) - #145743 (doc: fix some typos in comment) - #145745 (tests: Ignore basic-stepping.rs on LoongArch) Failed merges: - #145670 (port `sanitize` attribute to the new parsing infrastructure) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 28 pull requests Successful merges: - #132087 (Fix overly restrictive lifetime in `core::panic::Location::file` return type) - #137396 (Recover `param: Ty = EXPR`) - #137457 (Fix host code appearing in Wasm binaries) - #142185 (Convert moves of references to copies in ReferencePropagation) - #144648 (Implementation: `#[feature(nonpoison_rwlock)]`) - #144897 (print raw lifetime idents with r#) - #145218 ([Debuginfo] improve enum value formatting in LLDB for better readability) - #145380 (Add codegen-llvm regression tests) - #145573 (Add an experimental unsafe(force_target_feature) attribute.) - #145597 (resolve: Remove `ScopeSet::Late`) - #145633 (Fix some typos in LocalKey documentation) - #145641 (On E0277, point at type that doesn't implement bound) - #145669 (rustdoc-search: GUI tests check for `//` in URL) - #145695 (Introduce ProjectionElem::try_map.) - #145710 (Fix the ABI parameter inconsistency issue in debug.rs for LoongArch64) - #145726 (Experiment: Reborrow trait) - #145731 (Make raw pointers work in type-based search) - #145736 (triagebot: Update style team reviewers) - #145738 (Uplift rustc_mir_transform::coverage::counters::union_find to rustc_data_structures.) - #145742 (rustdoc js: Even more typechecking improvments ) - #145743 (doc: fix some typos in comment) - #145745 (tests: Ignore basic-stepping.rs on LoongArch) - #145747 (Refactor lint buffering to avoid requiring a giant enum) - #145751 (fix(lexer): Allow '-' in the frontmatter infostring continue set) - #145761 (Add aarch64_be-unknown-hermit target) - #145762 (convert strings to symbols in attr diagnostics) - #145763 (Ship LLVM tools for the correct target when cross-compiling) - #145765 (Revert suggestions for missing methods in tuples) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #145218 - nilptr:nilptr/feat/lldb-enum-pretty-printer, r=Mark-Simulacrum [Debuginfo] improve enum value formatting in LLDB for better readability > TL;DR: When debugging with CodeLLDB, I noticed enum values were often hard to read because LLDB lists every possible variant, resulting in a verbose and cluttered view, even though only one variant is actually valid. Interestingly, raw enum types display nicely. After some investigation, I found that `&enum` values get classified as `Other`, so it falls back to `DefaultSyntheticProvider`, which causes this verbose output. ## What does this PR do? This PR contains 2 commits: 1. change the enum value formatting from showing 2 separate fields (`value` for attached data and `$discr$` for the discriminator) to a concise `<readable variant name>: <attached data>` format 2. dereference pointer types in `classify_rust_type` so that it can return more accurate type for reference type ## Self-test proof Before: <img width="1706" height="799" alt="before" src="https://github.com/user-attachments/assets/b66c7e22-990a-4da5-9036-34e3f9f62367" /> After: <img width="1541" height="678" alt="after" src="https://github.com/user-attachments/assets/36db32e2-f822-4883-8f17-cb8067e509f6" />

Rollup of 28 pull requests Successful merges: - rust-lang/rust#132087 (Fix overly restrictive lifetime in `core::panic::Location::file` return type) - rust-lang/rust#137396 (Recover `param: Ty = EXPR`) - rust-lang/rust#137457 (Fix host code appearing in Wasm binaries) - rust-lang/rust#142185 (Convert moves of references to copies in ReferencePropagation) - rust-lang/rust#144648 (Implementation: `#[feature(nonpoison_rwlock)]`) - rust-lang/rust#144897 (print raw lifetime idents with r#) - rust-lang/rust#145218 ([Debuginfo] improve enum value formatting in LLDB for better readability) - rust-lang/rust#145380 (Add codegen-llvm regression tests) - rust-lang/rust#145573 (Add an experimental unsafe(force_target_feature) attribute.) - rust-lang/rust#145597 (resolve: Remove `ScopeSet::Late`) - rust-lang/rust#145633 (Fix some typos in LocalKey documentation) - rust-lang/rust#145641 (On E0277, point at type that doesn't implement bound) - rust-lang/rust#145669 (rustdoc-search: GUI tests check for `//` in URL) - rust-lang/rust#145695 (Introduce ProjectionElem::try_map.) - rust-lang/rust#145710 (Fix the ABI parameter inconsistency issue in debug.rs for LoongArch64) - rust-lang/rust#145726 (Experiment: Reborrow trait) - rust-lang/rust#145731 (Make raw pointers work in type-based search) - rust-lang/rust#145736 (triagebot: Update style team reviewers) - rust-lang/rust#145738 (Uplift rustc_mir_transform::coverage::counters::union_find to rustc_data_structures.) - rust-lang/rust#145742 (rustdoc js: Even more typechecking improvments ) - rust-lang/rust#145743 (doc: fix some typos in comment) - rust-lang/rust#145745 (tests: Ignore basic-stepping.rs on LoongArch) - rust-lang/rust#145747 (Refactor lint buffering to avoid requiring a giant enum) - rust-lang/rust#145751 (fix(lexer): Allow '-' in the frontmatter infostring continue set) - rust-lang/rust#145761 (Add aarch64_be-unknown-hermit target) - rust-lang/rust#145762 (convert strings to symbols in attr diagnostics) - rust-lang/rust#145763 (Ship LLVM tools for the correct target when cross-compiling) - rust-lang/rust#145765 (Revert suggestions for missing methods in tuples) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned Mark-Simulacrum Aug 10, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Aug 10, 2025

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nilptr added 3 commits August 17, 2025 21:15

feat(lldb debug info): improve enum value formatting in lldb

12eb1a0

feat(lldb debug info): deref pointer types for more accurate rust typ…

c39ebea

…e classification

fix: python formatting error

6be749b

nilptr force-pushed the nilptr/feat/lldb-enum-pretty-printer branch from 81979cd to 6be749b Compare August 17, 2025 13:15

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 22, 2025

jhpratt mentioned this pull request Aug 22, 2025

Rollup of 20 pull requests #145764

Closed

jhpratt mentioned this pull request Aug 23, 2025

Rollup of 28 pull requests #145773

Merged

bors merged commit 5cfdbd6 into rust-lang:master Aug 23, 2025
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rustbot added this to the 1.91.0 milestone Aug 23, 2025

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[Debuginfo] improve enum value formatting in LLDB for better readability #145218

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nilptr commented Aug 10, 2025

What does this PR do?

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