[clang] acc3ce9 - [Format] Don't derive pointers right based on space before method ref-qualifiers

[Sam McCall via cfe-commits]

Author: Sam McCall
Date: 2022-02-04T12:13:58+01:00
New Revision: acc3ce945c32a71ec077df379c99d859f31cc741

URL: https://github.com/llvm/llvm-project/commit/acc3ce945c32a71ec077df379c99d859f31cc741
DIFF: https://github.com/llvm/llvm-project/commit/acc3ce945c32a71ec077df379c99d859f31cc741.diff

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

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.

Differential Revision: https://reviews.llvm.org/D118921

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index daa815106049..551d8cfe7ec1 100644
--- a/clang/lib/Format/Format.cpp
+++ b/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"
@@ -1940,6 +1941,14 @@ class Formatter : public TokenAnalyzer {
       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)

diff  --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 96efc0e029e0..565b125dd1bc 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -9710,6 +9710,25 @@ TEST_F(FormatTest, UnderstandsFunctionRefQualification) {
                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) {