[clang-tidy][libc] Fix namespace check with macro (#68134)

The name of the namespace for LLVM's libc is now provided by a macro.
The ImplementationNamespaceCheck was updated to handle this, but the
CalleeNamespaceCheck was missed. This patch updates the
CalleeNamespaceCheck to handle the macro.

clang-tools-extra/clang-tidy/llvmlibc/CalleeNamespaceCheck.cpp

@@ -7,9 +7,11 @@
 //===----------------------------------------------------------------------===//
 
 #include "CalleeNamespaceCheck.h"
+#include "NamespaceConstants.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 
+#include "clang/ASTMatchers/ASTMatchers.h"
 #include "llvm/ADT/StringSet.h"
 
 using namespace clang::ast_matchers;
@@ -45,19 +47,22 @@ void CalleeNamespaceCheck::check(const MatchFinder::MatchResult &Result) {
   if (FuncDecl->getBuiltinID() != 0)
     return;
 
-  // If the outermost namespace of the function is __llvm_libc, we're good.
+  // If the outermost namespace of the function is a macro that starts with
+  // __llvm_libc, we're good.
   const auto *NS = dyn_cast<NamespaceDecl>(getOutermostNamespace(FuncDecl));
-  if (NS && NS->getName() == "__llvm_libc")
+  if (NS && Result.SourceManager->isMacroBodyExpansion(NS->getLocation()) &&
+      NS->getName().starts_with(RequiredNamespaceStart))
     return;
 
   const DeclarationName &Name = FuncDecl->getDeclName();
   if (Name.isIdentifier() &&
       IgnoredFunctions.contains(Name.getAsIdentifierInfo()->getName()))
     return;
 
-  diag(UsageSiteExpr->getBeginLoc(), "%0 must resolve to a function declared "
-                                     "within the '__llvm_libc' namespace")
-      << FuncDecl;
+  diag(UsageSiteExpr->getBeginLoc(),
+       "%0 must resolve to a function declared "
+       "within the namespace defined by the '%1' macro")
+      << FuncDecl << RequiredNamespaceMacroName;
 
   diag(FuncDecl->getLocation(), "resolves to this declaration",
        clang::DiagnosticIDs::Note);

clang-tools-extra/clang-tidy/llvmlibc/ImplementationInNamespaceCheck.cpp

@@ -7,16 +7,14 @@
 //===----------------------------------------------------------------------===//
 
 #include "ImplementationInNamespaceCheck.h"
+#include "NamespaceConstants.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 
 using namespace clang::ast_matchers;
 
 namespace clang::tidy::llvm_libc {
 
-const static StringRef RequiredNamespaceStart = "__llvm_libc";
-const static StringRef RequiredNamespaceMacroName = "LIBC_NAMESPACE";
-
 void ImplementationInNamespaceCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
       translationUnitDecl(

clang-tools-extra/clang-tidy/llvmlibc/NamespaceConstants.h

@@ -0,0 +1,16 @@
+//===--- NamespaceConstants.h -----------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/StringRef.h"
+
+namespace clang::tidy::llvm_libc {
+
+const static StringRef RequiredNamespaceStart = "__llvm_libc";
+const static StringRef RequiredNamespaceMacroName = "LIBC_NAMESPACE";
+
+} // namespace clang::tidy::llvm_libc

clang-tools-extra/docs/ReleaseNotes.rst

@@ -241,6 +241,11 @@ Changes in existing checks
   <clang-tidy/checks/llvm/namespace-comment>` check to provide fixes for
   ``inline`` namespaces in the same format as :program:`clang-format`.
 
+- Improved :doc:`llvmlibc-callee-namespace
+  <clang-tidy/checks/llvmlibc/callee-namespace>` to support
+  customizable namespace. This matches the change made to implementation in
+  namespace.
+
 - Improved :doc:`llvmlibc-implementation-in-namespace
   <clang-tidy/checks/llvmlibc/implementation-in-namespace>` to support
   customizable namespace. This further allows for testing the libc when the
@@ -319,6 +324,7 @@ Changes in existing checks
   <clang-tidy/checks/readability/static-accessed-through-instance>` check to
   identify calls to static member functions with out-of-class inline definitions.
 
+
 Removed checks
 ^^^^^^^^^^^^^^
 

clang-tools-extra/docs/clang-tidy/checks/llvmlibc/callee-namespace.rst

@@ -3,14 +3,18 @@
 llvmlibc-callee-namespace
 ====================================
 
-Checks all calls resolve to functions within ``__llvm_libc`` namespace.
+Checks all calls resolve to functions within correct namespace.
 
 .. code-block:: c++
 
-    namespace __llvm_libc {
+    // Implementation inside the LIBC_NAMESPACE namespace.
+    // Correct if:
+    // - LIBC_NAMESPACE is a macro
+    // - LIBC_NAMESPACE expansion starts with `__llvm_libc`
+    namespace LIBC_NAMESPACE {
 
     // Allow calls with the fully qualified name.
-    __llvm_libc::strlen("hello");
+    LIBC_NAMESPACE::strlen("hello");
 
     // Allow calls to compiler provided functions.
     (void)__builtin_abs(-1);
@@ -21,4 +25,4 @@ Checks all calls resolve to functions within ``__llvm_libc`` namespace.
     // Disallow calling into functions in the global namespace.
     ::strlen("!");
 
-    } // namespace __llvm_libc
+    } // namespace LIBC_NAMESPACE

clang-tools-extra/test/clang-tidy/checkers/llvmlibc/callee-namespace.cpp

@@ -1,6 +1,16 @@
 // RUN: %check_clang_tidy %s llvmlibc-callee-namespace %t
 
+#define OTHER_MACRO_NAMESPACE custom_namespace
+namespace OTHER_MACRO_NAMESPACE {
+  void wrong_name_macro_func() {}
+}
+
 namespace __llvm_libc {
+  void right_name_no_macro_func() {}
+}
+
+#define LIBC_NAMESPACE __llvm_libc_xyz
+namespace LIBC_NAMESPACE {
 namespace nested {
 void nested_func() {}
 } // namespace nested
@@ -22,12 +32,12 @@ struct global_struct {
   int operator()() const { return 0; }
 };
 
-namespace __llvm_libc {
+namespace LIBC_NAMESPACE {
 void Test() {
   // Allow calls with the fully qualified name.
-  __llvm_libc::libc_api_func();
-  __llvm_libc::nested::nested_func();
-  void (*qualifiedPtr)(void) = __llvm_libc::libc_api_func;
+  LIBC_NAMESPACE::libc_api_func();
+  LIBC_NAMESPACE::nested::nested_func();
+  void (*qualifiedPtr)(void) = LIBC_NAMESPACE::libc_api_func;
   qualifiedPtr();
 
   // Should not trigger on compiler provided function calls.
@@ -36,31 +46,41 @@ void Test() {
   // Bare calls are allowed as long as they resolve to the correct namespace.
   libc_api_func();
   nested::nested_func();
-  void (*barePtr)(void) = __llvm_libc::libc_api_func;
+  void (*barePtr)(void) = LIBC_NAMESPACE::libc_api_func;
   barePtr();
 
   // Allow calling entities defined in the namespace.
-  __llvm_libc::libc_api_struct{}();
+  LIBC_NAMESPACE::libc_api_struct{}();
 
   // Disallow calling into global namespace for implemented entrypoints.
   ::libc_api_func();
-  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'libc_api_func' must resolve to a function declared within the '__llvm_libc' namespace
-  // CHECK-MESSAGES: :15:6: note: resolves to this declaration
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'libc_api_func' must resolve to a function declared within the namespace defined by the 'LIBC_NAMESPACE' macro
+  // CHECK-MESSAGES: :25:6: note: resolves to this declaration
 
   // Disallow indirect references to functions in global namespace.
   void (*badPtr)(void) = ::libc_api_func;
   badPtr();
-  // CHECK-MESSAGES: :[[@LINE-2]]:26: warning: 'libc_api_func' must resolve to a function declared within the '__llvm_libc' namespace
-  // CHECK-MESSAGES: :15:6: note: resolves to this declaration
+  // CHECK-MESSAGES: :[[@LINE-2]]:26: warning: 'libc_api_func' must resolve to a function declared within the namespace defined by the 'LIBC_NAMESPACE' macro
+  // CHECK-MESSAGES: :25:6: note: resolves to this declaration
 
   // Allow calling into global namespace for specific functions.
   ::malloc();
 
   // Disallow calling on entities that are not in the namespace, but make sure
   // no crashes happen.
   global_struct{}();
-  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: 'operator()' must resolve to a function declared within the '__llvm_libc' namespace
-  // CHECK-MESSAGES: :22:7: note: resolves to this declaration
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: 'operator()' must resolve to a function declared within the namespace defined by the 'LIBC_NAMESPACE' macro
+  // CHECK-MESSAGES: :32:7: note: resolves to this declaration
+
+  OTHER_MACRO_NAMESPACE::wrong_name_macro_func();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'wrong_name_macro_func' must resolve to a function declared within the namespace defined by the 'LIBC_NAMESPACE' macro
+  // CHECK-MESSAGES: :3:31: note: expanded from macro 'OTHER_MACRO_NAMESPACE'
+  // CHECK-MESSAGES: :5:8: note: resolves to this declaration
+
+  __llvm_libc::right_name_no_macro_func();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'right_name_no_macro_func' must resolve to a function declared within the namespace defined by the 'LIBC_NAMESPACE' macro
+  // CHECK-MESSAGES: :9:8: note: resolves to this declaration
+
 }
 
 } // namespace __llvm_libc