clang unused dim
Fades out unused C/C++ symbols directly in the editor. Detection is pure text analysis over the open
file plus a workspace-wide token index — no clangd, no compiler, no compile_commands.json — so it
works on vendor embedded trees (Renesas CC-RL / e2 studio / CS+, IAR, Keil) where a language server
cannot realistically be configured.
Features
- Single-file checks that work immediately, with no index and no setup: local variables declared
but never used, parameters that never appear in the body,
static functions and file-scope
static variables nothing in their own file references, and an extern declaration a .c file
never mentions again.
- Workspace-proven checks for what one file cannot decide — non-static functions and prototypes
that no file in the workspace calls, and a header's
extern declarations. These appear only once
the background index is ready and its evidence is complete.
- Silence instead of a guess. Dimming code that is actually in use is the failure that matters, so
wherever the evidence is incomplete — a
## token paste, inline assembly, an unreadable file,
unsaved edits, a rebuilding index — the affected verdicts are dropped rather than shown. The tool
deliberately under-reports.
- Reads the toolchain files a C parser would miss. Assembler, linker scripts and CC-RL subcommand
files are swept for identifiers, so an interrupt handler referenced only from
startup.s or an
ENTRY() in a linker script does not look dead. Leading underscores match both ways.
- Non-UTF-8 sources are handled, using the encoding VS Code resolves for each file, so Shift-JIS
CC-RL sources are analysed rather than turned into mojibake.
- A status bar item that says why nothing is dimmed, distinguishing "no unused symbols here" from
"this file cannot be judged", and naming the file that caused the refusal.
- An optional
#include hint (off by default) for recognised standard headers whose symbols never
appear in the file. It is advisory only — confirm with a build before deleting an include.
Usage
Works automatically on C and C++ files. Dimming appears as you edit for the single-file checks, and
once the workspace scan finishes for the cross-file ones. Press ctrl+alt+u (or run the toggle
command, listed in the palette as "Toggle dimming of unused symbols") to turn dimming on and off, and
click the status bar item (or run "Show unused-symbol verdict status") to see why a file or a kind is
not being judged.
Settings
| Setting |
Default |
Purpose |
clangUnusedDim.enabled |
true |
Master switch for all dimming. |
clangUnusedDim.opacity |
0.45 |
Opacity of dimmed identifiers (0 invisible, 1 normal). |
clangUnusedDim.localVariables |
true |
Dim locals declared but never used in their function body. |
clangUnusedDim.parameters |
true |
Dim parameters that never appear in the body. |
clangUnusedDim.staticFunctions |
true |
Dim static functions unreferenced in their own file. |
clangUnusedDim.staticVariables |
true |
Dim file-scope static variables unreferenced in their own file. |
clangUnusedDim.includeNonStaticFunctions |
true |
Dim non-static functions no file in the workspace calls. |
clangUnusedDim.functionDeclarations |
true |
Dim prototypes no file in the workspace calls. |
clangUnusedDim.externVariables |
true |
Dim unused extern declarations and workspace-proven-unused globals. |
clangUnusedDim.includes |
false |
Advisory #include hint for standard headers (off by default). |
Limitations
Worth knowing before trusting a verdict on unfamiliar code: the index only proves absence of use
within the opened workspace, so a header consumed from an SDK or a sibling repository looks unused;
the preprocessor is not evaluated; macro-assembled names, K&R definitions, __attribute__ carriers,
inline functions and files containing asm blocks are never analysed; and a name is counted as used
whenever the identifier reappears, so a same-named field or macro suppresses the report.
Requirements
VS Code 1.100.0 or later — the floor comes from vscode.workspace.decode, which resolves
files.encoding so Shift-JIS sources are read correctly. Nothing else: no compiler, no toolchain, no
index configuration. Virtual workspaces are supported in limited form.
