[PATCH] D118921: [Format] Don't derive pointers right based on space before method ref-qualifiers

[Sam McCall via Phabricator via cfe-commits]

sammccall created this revision.
sammccall added a reviewer: benhamilton.
sammccall requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

The second space in `void foo() &` is always produced by clang-format,
and isn't evidence of any particular style.

Before this patch, it was considered evidence of PAS_Right, because
there is a space before a pointerlike ampersand.

This caused the following code to have "unstable" pointer alignment:

  void a() &;
  void b() &;
  int *x;

PAS_Left, Derive=false would produce 'int* x' with other lines unchanged.
But subsequent formatting with Derive=true would produce 'int *x' again.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118921

Files:
  clang/lib/Format/Format.cpp
  clang/unittests/Format/FormatTest.cpp


Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -9683,6 +9683,25 @@
                AlignLeftBreakTemplate);
 
   verifyFormat("void (*foopt)(int) = &func;");
+
+  FormatStyle DerivePointerAlignment = getLLVMStyle();
+  DerivePointerAlignment.DerivePointerAlignment = true;
+  // There's always a space between the function and its trailing qualifiers.
+  // This isn't evidence for PAS_Right (or for PAS_Left).
+  std::string Prefix = "void a() &;\n"
+                       "void b() &;\n";
+  verifyFormat(Prefix + "int* x;", DerivePointerAlignment);
+  verifyFormat(Prefix + "int *x;", DerivePointerAlignment);
+  // Same if the function is an overloaded operator instead.
+  Prefix = "void operator()() &;\n"
+           "void operator()() &;\n";
+  verifyFormat(Prefix + "int* x;", DerivePointerAlignment);
+  verifyFormat(Prefix + "int *x;", DerivePointerAlignment);
+  // However a space between cv-qualifiers and ref-qualifiers *is* evidence.
+  Prefix = "void a() const &;\n"
+           "void b() const &;\n";
+  EXPECT_EQ(Prefix + "int *x;",
+            format(Prefix + "int* x;", DerivePointerAlignment));
 }
 
 TEST_F(FormatTest, UnderstandsNewAndDelete) {
Index: clang/lib/Format/Format.cpp
===================================================================
--- clang/lib/Format/Format.cpp
+++ clang/lib/Format/Format.cpp
@@ -18,6 +18,7 @@
 #include "ContinuationIndenter.h"
 #include "DefinitionBlockSeparator.h"
 #include "FormatInternal.h"
+#include "FormatToken.h"
 #include "FormatTokenLexer.h"
 #include "NamespaceEndCommentsFixer.h"
 #include "QualifierAlignmentFixer.h"
@@ -1945,6 +1946,17 @@
       for (FormatToken *Tok = Line->First; Tok && Tok->Next; Tok = Tok->Next) {
         if (!Tok->is(TT_PointerOrReference))
           continue;
+        // Don't treat space in `void foo() &&` as evidence.
+        if (const auto *Prev = Tok->getPreviousNonComment()) {
+          if (Prev->is(tok::r_paren) && Prev->MatchingParen) {
+            if (const auto *Func =
+                    Prev->MatchingParen->getPreviousNonComment()) {
+              if (Func->isOneOf(TT_FunctionDeclarationName, TT_StartOfName,
+                                TT_OverloadedOperator))
+                continue;
+            }
+          }
+        }
         bool SpaceBefore = Tok->hasWhitespaceBefore();
         bool SpaceAfter = Tok->Next->hasWhitespaceBefore();
         if (SpaceBefore && !SpaceAfter)


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