[PATCH] D68245: [Clangd] ExtractFunction: Don't extract body of enclosing function.

[Shaurya Gupta via Phabricator via cfe-commits]

SureYeaah created this revision.
SureYeaah added reviewers: sammccall, kadircet.
Herald added subscribers: cfe-commits, usaxena95, arphaman, jkorous, MaskRay, ilya-biryukov.
Herald added a project: clang.

This patch disable extraction of the body of the enclosing function.
`void f() [[{}]]`

Extracting this CompoundStmt would leave the enclosing function without
a body.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D68245

Files:
  clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
  clang-tools-extra/clangd/unittests/TweakTests.cpp


Index: clang-tools-extra/clangd/unittests/TweakTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/TweakTests.cpp
+++ clang-tools-extra/clangd/unittests/TweakTests.cpp
@@ -631,6 +631,14 @@
     F ([[int x = 0;]])
   )cpp";
   EXPECT_EQ(apply(MacroFailInput), "unavailable");
+
+  // Don't extract if we select the entire function body (CompoundStmt).
+  std::string CompoundFailInput = R"cpp(
+    void f() [[{
+      int a;
+    }]]
+  )cpp";
+  EXPECT_EQ(apply(CompoundFailInput), "unavailable");
 }
 
 TEST_F(ExtractFunctionTest, ControlFlow) {
Index: clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
===================================================================
--- clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
+++ clang-tools-extra/clangd/refactor/tweaks/ExtractFunction.cpp
@@ -218,6 +218,21 @@
   return toHalfOpenFileRange(SM, LangOpts, EnclosingFunction->getSourceRange());
 }
 
+// returns true if Child can be a single RootStmt being extracted from
+// EnclosingFunc.
+bool validSingleChild(const Node *Child, const FunctionDecl *EnclosingFunc) {
+  // Don't extract expressions.
+  // FIXME: We should extract expressions that are "statements" i.e. not
+  // subexpressions
+  if (Child->ASTNode.get<Expr>())
+    return false;
+  // Extracting the body of EnclosingFunc would remove it's definition.
+  if (const Stmt *S = Child->ASTNode.get<Stmt>())
+    if (EnclosingFunc->hasBody() && EnclosingFunc->getBody() == S)
+      return false;
+  return true;
+}
+
 // FIXME: Check we're not extracting from the initializer/condition of a control
 // flow structure.
 // FIXME: Check that we don't extract the compound statement of the
@@ -229,15 +244,14 @@
   ExtZone.Parent = getParentOfRootStmts(CommonAnc);
   if (!ExtZone.Parent || ExtZone.Parent->Children.empty())
     return llvm::None;
-  // Don't extract expressions.
-  // FIXME: We should extract expressions that are "statements" i.e. not
-  // subexpressions
-  if (ExtZone.Parent->Children.size() == 1 &&
-      ExtZone.getLastRootStmt()->ASTNode.get<Expr>())
-    return llvm::None;
   ExtZone.EnclosingFunction = findEnclosingFunction(ExtZone.Parent);
   if (!ExtZone.EnclosingFunction)
     return llvm::None;
+  // When there is a single RootStmt, we must check if it's valid for
+  // extraction.
+  if (ExtZone.Parent->Children.size() == 1 &&
+      !validSingleChild(ExtZone.getLastRootStmt(), ExtZone.EnclosingFunction))
+    return llvm::None;
   if (auto FuncRange =
           computeEnclosingFuncRange(ExtZone.EnclosingFunction, SM, LangOpts))
     ExtZone.EnclosingFuncRange = *FuncRange;


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