feat(graph): C++ parser — classes, namespaces, templates, exception flow

[shivasurya]

Summary

Stacked on #670 (C parser).

Adds the C++ parser. After this PR a .cpp project produces a fully
populated CodeGraph with Language=\"cpp\" on every node, plus the C++-
only constructs the security analysis layer needs: classes with
inheritance, methods with access modifiers, namespaces (named and
anonymous, including nesting), templates, and exception flow
(throw/try/catch).

Files

• graph/parser_cpp.go — new, ~890 lines. Class / namespace /
  template / field / throw / try / call / struct / enum / typedef. Uses
  currentContext to detect class membership and propagate namespace
  PackageName through the AST recursion.
• graph/parser_cpp_test.go — TestParseCppEndToEnd (15 sub-tests
  covering every gap-analysis point from the tech spec) plus four
  targeted unit tests for defensive paths.
• graph/testdata/cpp/{example.cpp,buffer.hpp} — single-project
  fixture exercising every C++ construct the parser handles.
• graph/parser.go — modified. Two existing cases gained a C++ branch
  (function_definition, call_expression); five new cases for
  C++-only node types; existing struct_specifier / enum_specifier /
  type_definition cases now dispatch to the C-flavour or C++-flavour
  parse function based on file type. Java-only handlers (block,
  if/while/do/for, yield, binary_expression, class_declaration,
  block_comment) gated by isJavaSourceFile to fix cross-language
  pollution that produced Java-tagged nodes inside C/C++ files.
• graph/parser_c.go — minor: parseCLikeDeclaration now routes
  destructor-shaped declarations to the C++ helper when in class context;
  childrenByFieldName renamed to childDeclarators (linter caught
  unused generality).
• graph/graph_test.go — two existing tests updated to reflect the
  now-correct reality: .cpp files are parsed (not ignored), and the
  Java BlockStmt leak that inflated Python-test node counts is fixed.

Design choices

• Separate files per language. parser_c.go and parser_cpp.go are
  independent. Where the AST shape is genuinely identical
  (declaration, preproc_include), the existing C functions take an
  isCpp flag and emit the right Language tag. Where the shape differs
  (classes, namespaces, templates, throw/try, methods inside class
  bodies), each language has its own parse function. Where the shape is
  similar but C++ adds features (struct inheritance, scoped enums), the
  C++ flavour is a separate function so future C++ extensions don't
  ripple into the C path.
• Method dispatch via currentContext. parseCppFunctionDefinition
  detects class membership via classFromContext(currentContext) and
  emits method_declaration instead of function_definition when
  inside a class body. Same primitive disambiguates field_declaration:
  int x; becomes a data member, void bar(); becomes a method
  declaration with is_declaration=true.
• Access specifier as side-channel state. tree-sitter emits
  access_specifier as a sibling preceding the fields/methods it
  governs. recordAccessSpecifier mutates the class node's
  Metadata[current_access]; subsequent handlers read it. This avoids
  a separate AST pre-pass while keeping the graph nodes
  context-independent (each field/method carries its own Modifier).
• Constants over magic strings. nodeType* and meta* declared
  next to the parser that emits them. C++-only constants live in
  parser_cpp.go; shared constants stay in parser_c.go.
• Pre-existing bugs fixed. Java-only parsers were producing
  Java-tagged nodes for non-Java files. Each gate is a single-line
  if isJavaSourceFile {} wrap — no Java parser internals touched.

Test plan

• go build ./... — clean
• go vet ./... — clean
• golangci-lint run ./graph/... — 0 issues
• go test ./... -count=1 — all 25 packages pass, zero regressions
• TestParseCppEndToEnd — 15 sub-tests covering every gap-analysis
  point: inheritance, namespace propagation, anonymous namespaces,
  access + override + virtual + pure virtual, destructors, class
  fields, templates, throw/try with catch types, dot/arrow/qualified
  calls, scoped enums, typedefs, C++ structs, header forward decls,
  and regression check against Java-tagged nodes leaking into C++
  files
• Targeted unit tests: forward class declaration, catch (...),
  nil template list, recordAccessSpecifier outside class context

[safedep]

SafeDep Report Summary

No dependency changes detected. Nothing to scan.

View complete scan results →

_{This report is generated by SafeDep Github App}

[github-actions]

Code Pathfinder Security Scan

No security issues detected.

Metric	Value
Files Scanned	10
Rules	205

---

_{Powered by Code Pathfinder}

[codecov]

Codecov Report

❌ Patch coverage is 87.19852% with 69 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.18%. Comparing base (a7d99f7) to head (b1dd894).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
sast-engine/graph/parser_cpp.go	85.19%	38 Missing and 31 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #671      +/-   ##
==========================================
+ Coverage   85.14%   85.18%   +0.03%     
==========================================
  Files         177      178       +1     
  Lines       25550    26064     +514     
==========================================
+ Hits        21754    22202     +448     
- Misses       2977     3012      +35     
- Partials      819      850      +31     

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[shivasurya]

• feat(python-sdk): @c_rule / @cpp_rule decorators with language scoping #678
• feat(cfg+scan+output): wire C/C++ pipeline end-to-end #677
• feat(extraction): C/C++ statement extraction #676
• feat(callgraph): C++ call graph builder #675
• feat(callgraph): C call graph builder #674
• feat(callgraph): C/C++ explicit type inference engines #673
• feat(callgraph): C/C++ module registry and include resolution #672
• feat(graph): C++ parser — classes, namespaces, templates, exception flow #671 👈 (View in Graphite)
• feat(graph): C parser — function defs, types, decls, calls, includes #670
• feat(graph/clike): shared C/C++ AST extraction helpers #669
• feat(graph): C/C++ file detection and tree-sitter parsing foundation #668
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[shivasurya]

Merge activity

• May 3, 1:15 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• May 3, 1:21 PM UTC: Graphite rebased this pull request as part of a merge.
• May 3, 1:22 PM UTC: @shivasurya merged this pull request with Graphite.