[clang] 3e333cc - [clang-format] Fix PointerAlignmentRight with AlignConsecutiveDeclarations

Björn Schäpers via cfe-commits cfe-commits at lists.llvm.org
Thu Jun 3 08:55:01 PDT 2021


Author: Gerhard Gappmeier
Date: 2021-06-03T17:55:11+02:00
New Revision: 3e333cc82e42e1e2ecc974d896489eebe1a5edc2

URL: https://github.com/llvm/llvm-project/commit/3e333cc82e42e1e2ecc974d896489eebe1a5edc2
DIFF: https://github.com/llvm/llvm-project/commit/3e333cc82e42e1e2ecc974d896489eebe1a5edc2.diff

LOG: [clang-format] Fix PointerAlignmentRight with AlignConsecutiveDeclarations

This re-applies the old patch D27651, which was never landed, into the
latest "main" branch, without understanding the code. I just applied
the changes "mechanically" and made it compiling again.

This makes the right pointer alignment working as expected.
Fixes https://llvm.org/PR27353

For instance

const char* const* v1;
float const* v2;
SomeVeryLongType const& v3;

was formatted as

const char *const *     v1;
float const *           v2;
SomeVeryLongType const &v3;

This patch keep the *s or &s aligned to the right, next to their variable.
The above example is now formatted as

const char *const      *v1;
float const            *v2;
SomeVeryLongType const &v3;

It is a pity that this still does not work with clang-format in 2021,
even though there was a fix available in 2016. IMHO right pointer alignment
is the default case in C, because syntactically the pointer belongs to the
variable.

See

int* a, b, c; // wrong, just the 1st variable is a pointer

vs.

int *a, *b, *c; // right

Prominent example is the Linux kernel coding style.

Some styles argue the left pointer alignment is better and declaration
lists as shown above should be avoided. That's ok, as different projects
can use different styles, but this important style should work too.

I hope that somebody that has a better understanding about the code,
can take over this patch and land it into main.

For now I must maintain this fork to make it working for our projects.

Cheers,
Gerhard.

Differential Revision: https://reviews.llvm.org/D103245

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Format/WhitespaceManager.cpp
    clang/unittests/Format/FormatTest.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 11bcac075c241..6d3582a6297d6 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -259,6 +259,9 @@ clang-format
 - ``git-clang-format`` no longer formats changes to symbolic links. (Fixes
   https://llvm.org/PR46992.)
 
+- Makes ``PointerAligment: Right`` working with ``AlignConsecutiveDeclarations``.
+  (Fixes https://llvm.org/PR27353)
+
 libclang
 --------
 

diff  --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index e78c5c4df5866..515cb7941e785 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -262,7 +262,8 @@ void WhitespaceManager::calculateLineBreakInformation() {
 // Align a single sequence of tokens, see AlignTokens below.
 template <typename F>
 static void
-AlignTokenSequence(unsigned Start, unsigned End, unsigned Column, F &&Matches,
+AlignTokenSequence(const FormatStyle &Style, unsigned Start, unsigned End,
+                   unsigned Column, F &&Matches,
                    SmallVector<WhitespaceManager::Change, 16> &Changes) {
   bool FoundMatchOnLine = false;
   int Shift = 0;
@@ -365,9 +366,22 @@ AlignTokenSequence(unsigned Start, unsigned End, unsigned Column, F &&Matches,
       Changes[i].Spaces += Shift;
 
     assert(Shift >= 0);
+
     Changes[i].StartOfTokenColumn += Shift;
     if (i + 1 != Changes.size())
       Changes[i + 1].PreviousEndOfTokenColumn += Shift;
+
+    // If PointerAlignment is PAS_Right, keep *s or &s next to the token
+    if (Style.PointerAlignment == FormatStyle::PAS_Right &&
+        Changes[i].Spaces != 0) {
+      for (int Previous = i - 1;
+           Previous >= 0 &&
+           Changes[Previous].Tok->getType() == TT_PointerOrReference;
+           --Previous) {
+        Changes[Previous + 1].Spaces -= Shift;
+        Changes[Previous].Spaces += Shift;
+      }
+    }
   }
 }
 
@@ -437,8 +451,8 @@ static unsigned AlignTokens(
   // containing any matching token to be aligned and located after such token.
   auto AlignCurrentSequence = [&] {
     if (StartOfSequence > 0 && StartOfSequence < EndOfSequence)
-      AlignTokenSequence(StartOfSequence, EndOfSequence, MinColumn, Matches,
-                         Changes);
+      AlignTokenSequence(Style, StartOfSequence, EndOfSequence, MinColumn,
+                         Matches, Changes);
     MinColumn = 0;
     MaxColumn = UINT_MAX;
     StartOfSequence = 0;
@@ -728,12 +742,6 @@ void WhitespaceManager::alignConsecutiveDeclarations() {
   if (Style.AlignConsecutiveDeclarations == FormatStyle::ACS_None)
     return;
 
-  // FIXME: Currently we don't handle properly the PointerAlignment: Right
-  // The * and & are not aligned and are left dangling. Something has to be done
-  // about it, but it raises the question of alignment of code like:
-  //   const char* const* v1;
-  //   float const* v2;
-  //   SomeVeryLongType const& v3;
   AlignTokens(
       Style,
       [](Change const &C) {

diff  --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index efabaabf6e7f5..79d838cb28b7a 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -14915,6 +14915,7 @@ TEST_F(FormatTest, AlignConsecutiveDeclarations) {
   FormatStyle Alignment = getLLVMStyle();
   Alignment.AlignConsecutiveMacros = FormatStyle::ACS_Consecutive;
   Alignment.AlignConsecutiveDeclarations = FormatStyle::ACS_None;
+  Alignment.PointerAlignment = FormatStyle::PAS_Right;
   verifyFormat("float const a = 5;\n"
                "int oneTwoThree = 123;",
                Alignment);
@@ -14950,8 +14951,8 @@ TEST_F(FormatTest, AlignConsecutiveDeclarations) {
   verifyFormat("int      oneTwoThree{0}; // comment\n"
                "unsigned oneTwo;         // comment",
                Alignment);
-  verifyFormat("unsigned int *      a;\n"
-               "int *               b;\n"
+  verifyFormat("unsigned int       *a;\n"
+               "int                *b;\n"
                "unsigned int Const *c;\n"
                "unsigned int const *d;\n"
                "unsigned int Const &e;\n"
@@ -15073,9 +15074,11 @@ TEST_F(FormatTest, AlignConsecutiveDeclarations) {
                "  double        bar();\n"
                "};\n",
                Alignment);
+
+  // PAS_Right
   EXPECT_EQ("void SomeFunction(int parameter = 0) {\n"
             "  int const i   = 1;\n"
-            "  int *     j   = 2;\n"
+            "  int      *j   = 2;\n"
             "  int       big = 10000;\n"
             "\n"
             "  unsigned oneTwoThree = 123;\n"
@@ -15096,6 +15099,161 @@ TEST_F(FormatTest, AlignConsecutiveDeclarations) {
                    "int ll=10000;\n"
                    "}",
                    Alignment));
+  EXPECT_EQ("void SomeFunction(int parameter = 0) {\n"
+            "  int const i   = 1;\n"
+            "  int     **j   = 2, ***k;\n"
+            "  int      &k   = i;\n"
+            "  int     &&l   = i + j;\n"
+            "  int       big = 10000;\n"
+            "\n"
+            "  unsigned oneTwoThree = 123;\n"
+            "  int      oneTwo      = 12;\n"
+            "  method();\n"
+            "  float k  = 2;\n"
+            "  int   ll = 10000;\n"
+            "}",
+            format("void SomeFunction(int parameter= 0) {\n"
+                   " int const  i= 1;\n"
+                   "  int **j=2,***k;\n"
+                   "int &k=i;\n"
+                   "int &&l=i+j;\n"
+                   " int big  =  10000;\n"
+                   "\n"
+                   "unsigned oneTwoThree  =123;\n"
+                   "int oneTwo = 12;\n"
+                   "  method();\n"
+                   "float k= 2;\n"
+                   "int ll=10000;\n"
+                   "}",
+                   Alignment));
+  // variables are aligned at their name, pointers are at the right most
+  // position
+  verifyFormat("int   *a;\n"
+               "int  **b;\n"
+               "int ***c;\n"
+               "int    foobar;\n",
+               Alignment);
+
+  // PAS_Left
+  FormatStyle AlignmentLeft = Alignment;
+  AlignmentLeft.PointerAlignment = FormatStyle::PAS_Left;
+  EXPECT_EQ("void SomeFunction(int parameter = 0) {\n"
+            "  int const i   = 1;\n"
+            "  int*      j   = 2;\n"
+            "  int       big = 10000;\n"
+            "\n"
+            "  unsigned oneTwoThree = 123;\n"
+            "  int      oneTwo      = 12;\n"
+            "  method();\n"
+            "  float k  = 2;\n"
+            "  int   ll = 10000;\n"
+            "}",
+            format("void SomeFunction(int parameter= 0) {\n"
+                   " int const  i= 1;\n"
+                   "  int *j=2;\n"
+                   " int big  =  10000;\n"
+                   "\n"
+                   "unsigned oneTwoThree  =123;\n"
+                   "int oneTwo = 12;\n"
+                   "  method();\n"
+                   "float k= 2;\n"
+                   "int ll=10000;\n"
+                   "}",
+                   AlignmentLeft));
+  EXPECT_EQ("void SomeFunction(int parameter = 0) {\n"
+            "  int const i   = 1;\n"
+            "  int**     j   = 2;\n"
+            "  int&      k   = i;\n"
+            "  int&&     l   = i + j;\n"
+            "  int       big = 10000;\n"
+            "\n"
+            "  unsigned oneTwoThree = 123;\n"
+            "  int      oneTwo      = 12;\n"
+            "  method();\n"
+            "  float k  = 2;\n"
+            "  int   ll = 10000;\n"
+            "}",
+            format("void SomeFunction(int parameter= 0) {\n"
+                   " int const  i= 1;\n"
+                   "  int **j=2;\n"
+                   "int &k=i;\n"
+                   "int &&l=i+j;\n"
+                   " int big  =  10000;\n"
+                   "\n"
+                   "unsigned oneTwoThree  =123;\n"
+                   "int oneTwo = 12;\n"
+                   "  method();\n"
+                   "float k= 2;\n"
+                   "int ll=10000;\n"
+                   "}",
+                   AlignmentLeft));
+  // variables are aligned at their name, pointers are at the left most position
+  verifyFormat("int*   a;\n"
+               "int**  b;\n"
+               "int*** c;\n"
+               "int    foobar;\n",
+               AlignmentLeft);
+
+  // PAS_Middle
+  FormatStyle AlignmentMiddle = Alignment;
+  AlignmentMiddle.PointerAlignment = FormatStyle::PAS_Middle;
+  EXPECT_EQ("void SomeFunction(int parameter = 0) {\n"
+            "  int const i   = 1;\n"
+            "  int *     j   = 2;\n"
+            "  int       big = 10000;\n"
+            "\n"
+            "  unsigned oneTwoThree = 123;\n"
+            "  int      oneTwo      = 12;\n"
+            "  method();\n"
+            "  float k  = 2;\n"
+            "  int   ll = 10000;\n"
+            "}",
+            format("void SomeFunction(int parameter= 0) {\n"
+                   " int const  i= 1;\n"
+                   "  int *j=2;\n"
+                   " int big  =  10000;\n"
+                   "\n"
+                   "unsigned oneTwoThree  =123;\n"
+                   "int oneTwo = 12;\n"
+                   "  method();\n"
+                   "float k= 2;\n"
+                   "int ll=10000;\n"
+                   "}",
+                   AlignmentMiddle));
+  EXPECT_EQ("void SomeFunction(int parameter = 0) {\n"
+            "  int const i   = 1;\n"
+            "  int **    j   = 2, ***k;\n"
+            "  int &     k   = i;\n"
+            "  int &&    l   = i + j;\n"
+            "  int       big = 10000;\n"
+            "\n"
+            "  unsigned oneTwoThree = 123;\n"
+            "  int      oneTwo      = 12;\n"
+            "  method();\n"
+            "  float k  = 2;\n"
+            "  int   ll = 10000;\n"
+            "}",
+            format("void SomeFunction(int parameter= 0) {\n"
+                   " int const  i= 1;\n"
+                   "  int **j=2,***k;\n"
+                   "int &k=i;\n"
+                   "int &&l=i+j;\n"
+                   " int big  =  10000;\n"
+                   "\n"
+                   "unsigned oneTwoThree  =123;\n"
+                   "int oneTwo = 12;\n"
+                   "  method();\n"
+                   "float k= 2;\n"
+                   "int ll=10000;\n"
+                   "}",
+                   AlignmentMiddle));
+  // variables are aligned at their name, pointers are in the middle
+  verifyFormat("int *   a;\n"
+               "int *   b;\n"
+               "int *** c;\n"
+               "int     foobar;\n",
+               AlignmentMiddle);
+
   Alignment.AlignConsecutiveAssignments = FormatStyle::ACS_None;
   Alignment.AlignEscapedNewlines = FormatStyle::ENAS_DontAlign;
   verifyFormat("#define A \\\n"
@@ -15129,7 +15287,7 @@ TEST_F(FormatTest, AlignConsecutiveDeclarations) {
                Alignment);
   verifyFormat("void SomeFunction(int parameter = 0) {\n"
                "  int const i = 1;\n"
-               "  int *     j = 2;\n"
+               "  int      *j = 2;\n"
                "  int       big = 10000;\n"
                "}",
                Alignment);
@@ -15232,7 +15390,7 @@ TEST_F(FormatTest, AlignConsecutiveDeclarations) {
                "         float     b,\n"
                "         int       c,\n"
                "         uint32_t *d) {\n"
-               "  int *  e = 0;\n"
+               "  int   *e = 0;\n"
                "  float  f = 0;\n"
                "  double g = 0;\n"
                "}\n"


        


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