[clang] [clang-tools-extra] [llvm] [ADT] Fix IWYU for hashing-adjacent files (PR #194297)

[Fangrui Song via cfe-commits]

https://github.com/MaskRay updated https://github.com/llvm/llvm-project/pull/194297

>From 10d31c495a395496cda4af53afb48c0df5209f5d Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Sun, 26 Apr 2026 23:29:04 -0700
Subject: [PATCH] [ADT] Fix IWYU for hashing-adjacent files
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Add explicit includes so these files keep building after we trim
transitive includes from xxhash.h.

For example, FoldingSet.cpp calls llvm::uninitialized_copy, which is
declared in llvm/ADT/STLExtras.h and today reaches the file only
transitively.

Also drop the vestigial `#include "llvm/ADT/Hashing.h"` from
llvm/ADT/STLExtras.h — no name from Hashing.h is used there.
---
 clang-tools-extra/clangd/Config.h                            | 1 +
 clang/lib/StaticAnalyzer/Checkers/WebKit/PtrTypesSemantics.h | 1 +
 llvm/include/llvm/ADT/FoldingSet.h                           | 1 +
 llvm/include/llvm/ADT/STLExtras.h                            | 1 -
 llvm/include/llvm/ADT/StableHashing.h                        | 1 +
 llvm/include/llvm/ExecutionEngine/Orc/WaitingOnGraph.h       | 1 +
 llvm/lib/Support/FoldingSet.cpp                              | 1 +
 llvm/unittests/Support/xxhashTest.cpp                        | 1 +
 8 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/clang-tools-extra/clangd/Config.h b/clang-tools-extra/clangd/Config.h
index bc58c831e4e89..56d7ac453deeb 100644
--- a/clang-tools-extra/clangd/Config.h
+++ b/clang-tools-extra/clangd/Config.h
@@ -26,6 +26,7 @@
 
 #include "support/Context.h"
 #include "llvm/ADT/FunctionExtras.h"
+#include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringSet.h"
 #include <functional>
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/PtrTypesSemantics.h b/clang/lib/StaticAnalyzer/Checkers/WebKit/PtrTypesSemantics.h
index bcb4eee16bd2c..1d25a660247ab 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/PtrTypesSemantics.h
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/PtrTypesSemantics.h
@@ -14,6 +14,7 @@
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/PointerUnion.h"
 #include <optional>
+#include <string>
 
 namespace clang {
 class CXXBaseSpecifier;
diff --git a/llvm/include/llvm/ADT/FoldingSet.h b/llvm/include/llvm/ADT/FoldingSet.h
index 56e6e34dba591..0322dc5bddfe3 100644
--- a/llvm/include/llvm/ADT/FoldingSet.h
+++ b/llvm/include/llvm/ADT/FoldingSet.h
@@ -16,6 +16,7 @@
 #ifndef LLVM_ADT_FOLDINGSET_H
 #define LLVM_ADT_FOLDINGSET_H
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/STLForwardCompat.h"
 #include "llvm/ADT/SmallVector.h"
diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index ba9c5352fd736..fb9fdae1733f8 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -18,7 +18,6 @@
 #define LLVM_ADT_STLEXTRAS_H
 
 #include "llvm/ADT/ADL.h"
-#include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/STLForwardCompat.h"
 #include "llvm/ADT/STLFunctionalExtras.h"
 #include "llvm/ADT/iterator.h"
diff --git a/llvm/include/llvm/ADT/StableHashing.h b/llvm/include/llvm/ADT/StableHashing.h
index b6bd23c6945bf..0f5027488bee5 100644
--- a/llvm/include/llvm/ADT/StableHashing.h
+++ b/llvm/include/llvm/ADT/StableHashing.h
@@ -18,6 +18,7 @@
 #ifndef LLVM_ADT_STABLEHASHING_H
 #define LLVM_ADT_STABLEHASHING_H
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/xxhash.h"
 
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/WaitingOnGraph.h b/llvm/include/llvm/ExecutionEngine/Orc/WaitingOnGraph.h
index aaf09e0e90a6f..b0917b03aaa4e 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/WaitingOnGraph.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/WaitingOnGraph.h
@@ -14,6 +14,7 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/raw_ostream.h"
diff --git a/llvm/lib/Support/FoldingSet.cpp b/llvm/lib/Support/FoldingSet.cpp
index 977e4ca8c26ef..3df1e655a2ea1 100644
--- a/llvm/lib/Support/FoldingSet.cpp
+++ b/llvm/lib/Support/FoldingSet.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/ErrorHandling.h"
diff --git a/llvm/unittests/Support/xxhashTest.cpp b/llvm/unittests/Support/xxhashTest.cpp
index 84308ce130e72..6764efe8e5415 100644
--- a/llvm/unittests/Support/xxhashTest.cpp
+++ b/llvm/unittests/Support/xxhashTest.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/xxhash.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;