[clang] d999ce0 - Reland "[clang-repl] Extend the C support. (#89804)"

[Vassil Vassilev via cfe-commits]

Author: Vassil Vassilev
Date: 2024-06-04T13:55:03Z
New Revision: d999ce0302f06d250f6d496b56a5a5f2dc331e61

URL: https://github.com/llvm/llvm-project/commit/d999ce0302f06d250f6d496b56a5a5f2dc331e61
DIFF: https://github.com/llvm/llvm-project/commit/d999ce0302f06d250f6d496b56a5a5f2dc331e61.diff

LOG: Reland "[clang-repl] Extend the C support. (#89804)"

Original commit message:"

[clang-repl] Extend the C support. (#89804)

The IdResolver chain is the main way for C to implement lookup rules.  Every new
partial translation unit caused clang to exit the top-most scope which in turn
cleaned up the IdResolver chain. That was not an issue for C++ because its
lookup is implemented on the level of declaration contexts.

This patch keeps the IdResolver chain across partial translation units
maintaining proper C-style lookup infrastructure.
"

It was reverted in dfdf1c5fe45a82b9c578306f3d7627fd251d63f8 because it broke the
bots of lldb. This failure was subtle to debug but the current model does not
work well with ObjectiveC support in lldb. This patch does cleans up the
partial translation units in ObjectiveC. In future if we want to support
ObjectiveC we need to understand what exactly lldb is doing when recovering from
errors...

Added: 
    clang/test/Interpreter/execute.c

Modified: 
    clang/lib/Interpreter/IncrementalParser.cpp
    clang/lib/Sema/SemaDecl.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Interpreter/IncrementalParser.cpp b/clang/lib/Interpreter/IncrementalParser.cpp
index ef90fe9e6f545..5bc8385d874a1 100644
--- a/clang/lib/Interpreter/IncrementalParser.cpp
+++ b/clang/lib/Interpreter/IncrementalParser.cpp
@@ -387,8 +387,7 @@ std::unique_ptr<llvm::Module> IncrementalParser::GenModule() {
 
 void IncrementalParser::CleanUpPTU(PartialTranslationUnit &PTU) {
   TranslationUnitDecl *MostRecentTU = PTU.TUPart;
-  TranslationUnitDecl *FirstTU = MostRecentTU->getFirstDecl();
-  if (StoredDeclsMap *Map = FirstTU->getPrimaryContext()->getLookupPtr()) {
+  if (StoredDeclsMap *Map = MostRecentTU->getPrimaryContext()->getLookupPtr()) {
     for (auto &&[Key, List] : *Map) {
       DeclContextLookupResult R = List.getLookupResult();
       std::vector<NamedDecl *> NamedDeclsToRemove;
@@ -407,6 +406,16 @@ void IncrementalParser::CleanUpPTU(PartialTranslationUnit &PTU) {
       }
     }
   }
+
+  // FIXME: We should de-allocate MostRecentTU
+  for (Decl *D : MostRecentTU->decls()) {
+    auto *ND = dyn_cast<NamedDecl>(D);
+    if (!ND)
+      continue;
+    // Check if we need to clean up the IdResolver chain.
+    if (ND->getDeclName().getFETokenInfo())
+      getCI()->getSema().IdResolver.RemoveDecl(ND);
+  }
 }
 
 llvm::StringRef IncrementalParser::GetMangledName(GlobalDecl GD) const {

diff  --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 08483e6ebd67f..7ff05ae514ebe 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2284,9 +2284,13 @@ void Sema::ActOnPopScope(SourceLocation Loc, Scope *S) {
     if (LabelDecl *LD = dyn_cast<LabelDecl>(D))
       CheckPoppedLabel(LD, *this, addDiag);
 
-    // Remove this name from our lexical scope, and warn on it if we haven't
-    // already.
-    IdResolver.RemoveDecl(D);
+    // Partial translation units that are created in incremental processing must
+    // not clean up the IdResolver because PTUs should take into account the
+    // declarations that came from previous PTUs.
+    if (!PP.isIncrementalProcessingEnabled() || getLangOpts().ObjC)
+      IdResolver.RemoveDecl(D);
+
+    // Warn on it if we are shadowing a declaration.
     auto ShadowI = ShadowingDecls.find(D);
     if (ShadowI != ShadowingDecls.end()) {
       if (const auto *FD = dyn_cast<FieldDecl>(ShadowI->second)) {

diff  --git a/clang/test/Interpreter/execute.c b/clang/test/Interpreter/execute.c
new file mode 100644
index 0000000000000..44a3a32c93011
--- /dev/null
+++ b/clang/test/Interpreter/execute.c
@@ -0,0 +1,21 @@
+// REQUIRES: host-supports-jit
+// UNSUPPORTED: system-aix
+
+// RUN: cat %s | clang-repl -Xcc -xc -Xcc -Xclang -Xcc -verify | FileCheck %s
+// RUN: cat %s | clang-repl -Xcc -xc -Xcc -O2 -Xcc -Xclang -Xcc -verify| FileCheck %s
+int printf(const char *, ...);
+int i = 42; err // expected-error{{use of undeclared identifier}}
+int i = 42;
+struct S { float f; struct S *m;} s = {1.0, 0};
+// FIXME: Making foo inline fails to emit the function.
+int foo() { return 42; }
+void run() {                                                    \
+  printf("i = %d\n", i);                                        \
+  printf("S[f=%f, m=0x%llx]\n", s.f, (unsigned long long)s.m);  \
+  int r3 = foo();                                               \
+}
+run();
+// CHECK: i = 42
+// CHECK-NEXT: S[f=1.000000, m=0x0]
+
+%quit