[clang-tools-extra] [clangd] Index reserved symbols from `*intrin.h` system headers (PR #119735)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/119735

Summary:
`clangd` intentionally suppresses indexing symbols from system headers
as these are likely implementation details the user does not want.
Howver, there are plenty of system headers that provide extensions that
we want to index, such as vector intrinsic headers. This patch adds an
extra check for these commonly-named '*intrin.h' headers. This is not
fully inclusive for all symbols the user might want, but it's a good
start.

Fixes: https://github.com/llvm/llvm-project/issues/118684


>From 0c91459c6833e9ca7869184cb82e2509ac03f819 Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Thu, 12 Dec 2024 12:15:32 -0600
Subject: [PATCH] [clangd] Index reserved symbols from `*intrin.h` system
 headers

Summary:
`clangd` intentionally suppresses indexing symbols from system headers
as these are likely implementation details the user does not want.
Howver, there are plenty of system headers that provide extensions that
we want to index, such as vector intrinsic headers. This patch adds an
extra check for these commonly-named '*intrin.h' headers. This is not
fully inclusive for all symbols the user might want, but it's a good
start.

Fixes: https://github.com/llvm/llvm-project/issues/118684
---
 clang-tools-extra/clangd/index/SymbolCollector.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/clang-tools-extra/clangd/index/SymbolCollector.cpp b/clang-tools-extra/clangd/index/SymbolCollector.cpp
index 81125dbb1aeafc..6d0af20e31260c 100644
--- a/clang-tools-extra/clangd/index/SymbolCollector.cpp
+++ b/clang-tools-extra/clangd/index/SymbolCollector.cpp
@@ -550,9 +550,14 @@ bool SymbolCollector::shouldCollectSymbol(const NamedDecl &ND,
   // Avoid indexing internal symbols in protobuf generated headers.
   if (isPrivateProtoDecl(ND))
     return false;
+
+  // System headers that end with `intrin.h` likely contain useful symbols.
   if (!Opts.CollectReserved &&
       (hasReservedName(ND) || hasReservedScope(*ND.getDeclContext())) &&
-      ASTCtx.getSourceManager().isInSystemHeader(ND.getLocation()))
+      ASTCtx.getSourceManager().isInSystemHeader(ND.getLocation()) &&
+      !ASTCtx.getSourceManager()
+           .getFilename(ND.getLocation())
+           .ends_with("intrin.h"))
     return false;
 
   return true;