[clang] 22fc2cb - [clang-format] Fix AllowShortLambdasOnASingleLine interfering with lambda brace wrapping. (#81848)

[via cfe-commits]

Author: rmarker
Date: 2024-02-19T14:32:06-08:00
New Revision: 22fc2cb15d9e9bfb84145c6891fb748e8e52757e

URL: https://github.com/llvm/llvm-project/commit/22fc2cb15d9e9bfb84145c6891fb748e8e52757e
DIFF: https://github.com/llvm/llvm-project/commit/22fc2cb15d9e9bfb84145c6891fb748e8e52757e.diff

LOG: [clang-format] Fix AllowShortLambdasOnASingleLine interfering with lambda brace wrapping. (#81848)

Fix an issue where the lambda body left brace could sometimes fail to be
wrapped when AllowShortLambdasOnASingleLine is enabled.

Now, when BraceWrapping.BeforeLambdaBody is enabled, if the brace is not
wrapped, we prevent breaks in the lambda body.

Resolves #81845

Added: 
    

Modified: 
    clang/lib/Format/ContinuationIndenter.cpp
    clang/lib/Format/ContinuationIndenter.h
    clang/unittests/Format/FormatTest.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 97500ee41259f0..df44e6994c4784 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -1803,7 +1803,7 @@ void ContinuationIndenter::moveStatePastScopeOpener(LineState &State,
   }
 
   if (Current.MatchingParen && Current.is(BK_Block)) {
-    moveStateToNewBlock(State);
+    moveStateToNewBlock(State, Newline);
     return;
   }
 
@@ -1991,7 +1991,7 @@ void ContinuationIndenter::moveStatePastScopeCloser(LineState &State) {
   }
 }
 
-void ContinuationIndenter::moveStateToNewBlock(LineState &State) {
+void ContinuationIndenter::moveStateToNewBlock(LineState &State, bool NewLine) {
   if (Style.LambdaBodyIndentation == FormatStyle::LBI_OuterScope &&
       State.NextToken->is(TT_LambdaLBrace) &&
       !State.Line->MightBeFunctionDecl) {
@@ -2003,10 +2003,18 @@ void ContinuationIndenter::moveStateToNewBlock(LineState &State) {
       NestedBlockIndent + (State.NextToken->is(TT_ObjCBlockLBrace)
                                ? Style.ObjCBlockIndentWidth
                                : Style.IndentWidth);
+
+  // Even when wrapping before lambda body, the left brace can still be added to
+  // the same line. This occurs when checking whether the whole lambda body can
+  // go on a single line. In this case we have to make sure there are no line
+  // breaks in the body, otherwise we could just end up with a regular lambda
+  // body without the brace wrapped.
+  bool NoLineBreak = Style.BraceWrapping.BeforeLambdaBody && !NewLine &&
+                     State.NextToken->is(TT_LambdaLBrace);
+
   State.Stack.push_back(ParenState(State.NextToken, NewIndent,
                                    State.Stack.back().LastSpace,
-                                   /*AvoidBinPacking=*/true,
-                                   /*NoLineBreak=*/false));
+                                   /*AvoidBinPacking=*/true, NoLineBreak));
   State.Stack.back().NestedBlockIndent = NestedBlockIndent;
   State.Stack.back().BreakBeforeParameter = true;
 }

diff  --git a/clang/lib/Format/ContinuationIndenter.h b/clang/lib/Format/ContinuationIndenter.h
index 057b85bd32d505..2598947bb624c5 100644
--- a/clang/lib/Format/ContinuationIndenter.h
+++ b/clang/lib/Format/ContinuationIndenter.h
@@ -104,7 +104,7 @@ class ContinuationIndenter {
   /// Update 'State' according to the next token being one of ")>}]".
   void moveStatePastScopeCloser(LineState &State);
   /// Update 'State' with the next token opening a nested block.
-  void moveStateToNewBlock(LineState &State);
+  void moveStateToNewBlock(LineState &State, bool NewLine);
 
   /// Reformats a raw string literal.
   ///

diff  --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index d9e369296eed16..24f62af8ddcb87 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -22893,6 +22893,19 @@ TEST_F(FormatTest, FormatsLambdas) {
                LLVMWithBeforeLambdaBody);
   verifyFormat("FctWithTwoParams_SLS_All([]() { return 43; }, 87);",
                LLVMWithBeforeLambdaBody);
+  verifyFormat(
+      "FctWithTwoParams_SLS_All(\n"
+      "    87, []() { return LongLineThatWillForceBothParamsToNewLine(); });",
+      LLVMWithBeforeLambdaBody);
+  verifyFormat(
+      "FctWithTwoParams_SLS_All(\n"
+      "    87,\n"
+      "    []()\n"
+      "    {\n"
+      "      return "
+      "LongLineThatWillForceTheLambdaBodyToBeBrokenIntoMultipleLines();\n"
+      "    });",
+      LLVMWithBeforeLambdaBody);
   verifyFormat("FctWithOneNestedLambdas_SLS_All([]() { return 17; });",
                LLVMWithBeforeLambdaBody);
   verifyFormat(