[clang][CodeCompletion] Allow debuggers to code-complete reserved identifiers

[Michael137]

It is not uncommon for LLDB users to dig into internal implementation details of system types (including the STL). LLDB's expression evaluator makes use of Clang's code-completion facilities but currently reserved identifeirs are filtered out (clang::Decls created in LLDB don't have valid locations, so we would also fail to code-complete any identifiers with reserved prefixes, not just ones from system headers).

This patch permits Clang to code-complete reserved identifiers iff we're in the debugger.

The associated LLDB tests: #84890

rdar://124098023

[llvmbot]

@llvm/pr-subscribers-clang

Author: Michael Buch (Michael137)

Changes

It is not uncommon for LLDB users to dig into internal implementation details of system types (including the STL). LLDB's expression evaluator makes use of Clang's code-completion facilities but currently reserved identifeirs are filtered out (clang::Decls created in LLDB don't have valid locations, so we would also fail to code-complete any identifiers with reserved prefixes, not just ones from system headers).

This patch permits Clang to code-complete reserved identifiers iff we're in the debugger.

The associated LLDB tests: #84890

rdar://124098023

---

Full diff: https://github.com/llvm/llvm-project/pull/84891.diff

2 Files Affected:

• (modified) clang/lib/Sema/SemaCodeComplete.cpp (+4)
• (modified) clang/test/CodeCompletion/ordinary-name.c (+6-1)

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index c44be0df9b0a85..18a7f2d98340a3 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -764,6 +764,10 @@ getRequiredQualification(ASTContext &Context, const DeclContext *CurContext,
 // Filter out names reserved for the implementation if they come from a
 // system header.
 static bool shouldIgnoreDueToReservedName(const NamedDecl *ND, Sema &SemaRef) {
+  // Debuggers want access to all identifiers, including reserved ones.
+  if (SemaRef.getLangOpts().DebuggerSupport)
+    return false;
+
   ReservedIdentifierStatus Status = ND->isReserved(SemaRef.getLangOpts());
   // Ignore reserved names for compiler provided decls.
   if (isReservedInAllContexts(Status) && ND->getLocation().isInvalid())
diff --git a/clang/test/CodeCompletion/ordinary-name.c b/clang/test/CodeCompletion/ordinary-name.c
index c8181a248daa2f..93985619206173 100644
--- a/clang/test/CodeCompletion/ordinary-name.c
+++ b/clang/test/CodeCompletion/ordinary-name.c
@@ -5,6 +5,7 @@ typedef struct t _TYPEDEF;
 void foo() {
   int y;
   // RUN: %clang_cc1 -isystem %S/Inputs -fsyntax-only -code-completion-at=%s:%(line-1):9 %s -o - | FileCheck -check-prefix=CHECK-CC1 %s
+  // CHECK-CC1-NOT: __builtin_va_list
   // CHECK-CC1-NOT: __INTEGER_TYPE
   // CHECK-CC1: _Imaginary
   // CHECK-CC1: _MyPrivateType
@@ -15,4 +16,8 @@ void foo() {
   // CHECK-CC1: y
 
   // PR8744
-  // RUN: %clang_cc1 -isystem %S/Inputs -fsyntax-only -code-completion-at=%s:%(line-17):11 %s
+  // RUN: %clang_cc1 -isystem %S/Inputs -fsyntax-only -code-completion-at=%s:%(line-18):11 %s
+  
+  // RUN: %clang_cc1 -isystem %S/Inputs -fsyntax-only -fdebugger-support -code-completion-at=%s:%(line-15):9 %s -o - | FileCheck -check-prefix=CHECK-DBG %s
+  // CHECK-DBG: __builtin_va_list
+  // CHECK-DBG: __INTEGER_TYPE