gocg

A Go call graph analyzer inspired by clang-callgraph. Uses golang.org/x/tools (VTA, SSA, packages) to build precise call graphs for Go codebases, with an interactive REPL for exploration.

Installation

go install github.com/LiuYinCarl/gocg@latest

Or build from source:

git clone https://github.com/LiuYinCarl/gocg.git
cd gocg
go install .

Requires Go 1.21+.

Quick Start

# Analyze a Go project, enter interactive REPL
gocg /path/to/your/go/project

# Single lookup (non-interactive)
gocg /path/to/your/go/project --lookup 'pkg.FuncName'

# Exclude functions containing certain import paths
gocg . -x 'golang.org/x/tools,github.com/some/dep'

# Disable or clear cache
gocg . --no-cache
gocg . --clear-cache

Interactive REPL

>>> createTransport             # exact match → call graph; partial → search list
>>> ? createTransport           # filter mode: only branches containing filter keywords
>>> ! createTransport           # ignore mode: skip branches matching ignore keywords
>>> & createTransport           # reverse references: who calls this function

>>> @ filter keyword1 keyword2  # add filter keywords
>>> @ ignore keyword1 keyword2  # add ignore keywords
>>> @ del_fi keyword            # remove a filter keyword
>>> @ del_ig keyword            # remove an ignore keyword
>>> @ depth 3                   # set max print depth
>>> @ show                      # show current config
>>> @ reset                     # reset all config

Tab completion is supported for function names and @ subcommands.

How It Works

1. Load: go/packages loads the project and all dependencies
2. SSA: go/ssa builds static single-assignment form
3. VTA: go/callgraph/vta computes a precise call graph (no false-positive interface calls like CHA)
4. Filter: Only functions defined under the project directory are expanded; external calls appear as leaf nodes
5. Cache: Results are cached in .gocg-cache/ under the project directory, keyed by SHA256 of all .go file mtimes/sizes

CLI Flags

Flag	Description
<directory>	Go project directory to analyze (default: .)
-x p1,p2,...	Exclude functions whose full import path contains any of these substrings
--lookup func	Print call graph for a function and exit (no REPL)
--no-cache	Skip reading/writing cache
--clear-cache	Remove all cached files and exit

Comparison with clang-callgraph

Feature	clang-callgraph	gocg
Language	C/C++ (libclang)	Go (x/tools)
Input	compile_commands.json / .cpp	Go project directory
Call graph algorithm	Clang AST walk	VTA (Variable Type Analysis)
Interactive REPL	✅	✅
Filter / Ignore / Ref	✅	✅
Tab completion	✅	✅
Cache	✅	✅