Improve MCP validation efficiency and annotate public APIs with nodiscard by HarshPopat23 · Pull Request #3024 · sourcemeta/core

HarshPopat23 · 2026-10-16T06:34:02Z

Summary

Combines MCP validation performance and API safety improvements:

Validation Efficiency & Reduced Allocations:
- Replaced the ad-hoc strings() array-checking loop in src/core/mcp/validation.h with native member function is_array_of_strings() across �udience, sizes, stopSequences, and task environment object values.
- Eliminated redundant string copies on dispatch (const auto &name{...to_string()}) in sampling_block(), sampling_message_block(), �alid_content(), and �alid_input_requests().
- Reused bound string references across �nnotations() and icons() loops.
- Retained exact JSON number comparisons for annotation priority bounds (*priority < JSON{0} || *priority > JSON{1}) to preserve Decimal precision without rounding or overflow.
Annotate Public MCP Functions with [[nodiscard]]:
- Added [[nodiscard]] to all public query, validation, parsing, and factory functions across mcp_protocol.h, mcp_headers.h, mcp_results.h, mcp_capabilities.h, mcp_error.h, and mcp_logging.h to prevent callers from silently ignoring validation results or responses (excluding void-returning mcp_write_result).
- Updated est/mcp/mcp_helpers.h (EXPECT_MCP_REJECTS) and est/mcp/mcp_error_test.cc to cast discarded expressions to �oid for -Werror=unused-result compliance.

Testing

Full MSYS2 UCRT64 GCC 14.2 & Ninja build cleanly passing.
100% pass on all test suites:
- core.mcp: all 1,409 tests passed, 0 failed.
- core.json: passed.
- core.jsonrpc: passed.
Code formatted with repository's clang-format configuration.

cubic-dev-ai

All reported issues were addressed across 2 files

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augmentcode · 2026-10-16T06:39:19Z

🤖 Augment PR Summary

Summary: Improves MCP validation efficiency and makes ignored public API results visible.

Replaces the local string-array validator with JSON::is_array_of_strings().
Applies it to audiences, icon sizes, sampling stop sequences, and elicitation content arrays.
Borrows strings during sampling, content, and nested-request dispatch instead of copying them.
Reuses string references when checking audience roles and icon themes.
Checks nonnegative resource sizes using is_integral() and is_positive().
Preserves exact JSON-number comparisons for annotation priority bounds.
Adds [[nodiscard]] across protocol, header, result, capability, error, and logging APIs.
Leaves the void-returning mcp_write_result() unannotated.
Explicitly discards factory results in exception tests while preserving their evaluation.

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Review completed. 2 suggestions posted.

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HarshPopat23 · 2026-10-16T07:22:44Z

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cubic-dev-ai

All reported issues were addressed across 9 files (changes from recent commits).

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HarshPopat23 · 2026-10-16T08:42:57Z

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All reported issues were addressed across 9 files

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HarshPopat23 · 2026-10-16T09:01:51Z

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…card - Replace ad-hoc array of strings validation loop with is_array_of_strings() in validation.h. - Avoid unnecessary string allocations when dispatching message and content types. - Annotate public MCP functions across protocol, headers, results, capabilities, error, and logging with [[nodiscard]]. - Update test helpers to cast discarded results to void. Signed-off-by: HarshPopat23 <musichk61@gmail.com>

HarshPopat23 · 2026-10-16T09:04:48Z

augment review

jviotti · 2026-10-23T13:50:24Z

  try {
-    sourcemeta::core::mcp_make_resource_link(
-        sourcemeta::core::MCPProtocolVersion::V_2025_03_26, "file:///a", "a");
+    static_cast<void>(sourcemeta::core::mcp_make_resource_link(


Please use [[maybe_unused]] instead

jviotti · 2026-10-23T13:50:30Z

 #define EXPECT_MCP_REJECTS(expression, expected_message)                       \
  try {                                                                        \
-    expression;                                                                \
+    static_cast<void>(expression);                                             \


Signed-off-by: HarshPopat23 <musichk61@gmail.com>

jviotti · 2026-10-23T15:58:18Z

+        [[maybe_unused]] const auto &sourcemeta_test_result{                   \
+            sourcemeta_test_expression()};                                     \
+      }                                                                        \
+    }([&]() -> decltype(auto) { return (expression); });                       \


This looks very weird. I don't think you need this? Can you check? i.e. can't you provide the actual return type in the lambda declaration?

Signed-off-by: HarshPopat23 <musichk61@gmail.com>

HarshPopat23 · 2026-10-23T16:22:47Z

Thanks @jviotti

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HarshPopat23 force-pushed the perf/mcp-reduce-temporary-allocations branch from aa5d198 to ef8c35d Compare October 16, 2026 07:05

HarshPopat23 changed the title ~~Avoid temporary allocations in MCP validation and parameter parsing~~ Avoid temporary allocations in MCP validation Oct 16, 2026

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HarshPopat23 force-pushed the perf/mcp-reduce-temporary-allocations branch from ef8c35d to c704323 Compare October 16, 2026 08:04

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Comment thread src/core/mcp/include/sourcemeta/core/mcp_logging.h Outdated

HarshPopat23 changed the title ~~Avoid temporary allocations in MCP validation~~ Improve MCP validation efficiency and annotate public APIs with nodiscard Oct 16, 2026

HarshPopat23 force-pushed the perf/mcp-reduce-temporary-allocations branch from aea02e4 to 205435d Compare October 16, 2026 08:32

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Comment thread src/core/mcp/include/sourcemeta/core/mcp_error.h

Comment thread src/core/mcp/include/sourcemeta/core/mcp_results.h

HarshPopat23 force-pushed the perf/mcp-reduce-temporary-allocations branch from 205435d to d10e9ce Compare October 16, 2026 09:01

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HarshPopat23 closed this Oct 16, 2026

HarshPopat23 force-pushed the perf/mcp-reduce-temporary-allocations branch from d10e9ce to 8f7d7f2 Compare October 16, 2026 09:04

HarshPopat23 reopened this Oct 16, 2026

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HarshPopat23 added 2 commits October 23, 2026 19:34

test(mcp): use maybe_unused for intentionally ignored results

d9f0b68

Signed-off-by: HarshPopat23 <musichk61@gmail.com>

test(mcp): bind ignored results by reference

46fc79c

Signed-off-by: HarshPopat23 <musichk61@gmail.com>

HarshPopat23 requested a review from jviotti October 23, 2026 14:45

jviotti reviewed Oct 23, 2026

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test(mcp): simplify rejection helper with explicit lambda return type

026e10b

Signed-off-by: HarshPopat23 <musichk61@gmail.com>

HarshPopat23 requested a review from jviotti October 23, 2026 16:16

jviotti approved these changes Oct 23, 2026

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jviotti merged commit 3ce74df into sourcemeta:main Oct 23, 2026
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