[clang-format] Align preprocessor comments with #

Summary:
r312125, which introduced preprocessor indentation, shipped with a known
issue where "indentation of comments immediately before indented
preprocessor lines is toggled on each run". For example these two forms
toggle:

  #ifndef HEADER_H
  #define HEADER_H
  #if 1
  // comment
  #   define A 0
  #endif
  #endif

  #ifndef HEADER_H
  #define HEADER_H
  #if 1
     // comment
  #   define A 0
  #endif
  #endif

This happens because we check vertical alignment against the '#' yet
indent to the level of the 'define'. This patch resolves this issue by
aligning against the '#'.

Reviewers: krasimir, klimek, djasper

Reviewed By: krasimir

Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D42408

llvm-svn: 323904

1 files changed, 79 insertions, 15 deletions

diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index dcb1089a82c..cbabc459c4d 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -2595,21 +2595,85 @@ TEST_F(FormatTest, IndentPreprocessorDirectives) {
                    "code();\n"
                    "#endif",
                    Style));
-  // FIXME: The comment indent corrector in TokenAnnotator gets thrown off by
-  // preprocessor indentation.
-  EXPECT_EQ("#if 1\n"
-            "  // comment\n"
-            "#  define A 0\n"
-            "// comment\n"
-            "#  define B 0\n"
-            "#endif",
-            format("#if 1\n"
-                   "// comment\n"
-                   "#  define A 0\n"
-                   "   // comment\n"
-                   "#  define B 0\n"
-                   "#endif",
-                   Style));
+  // Keep comments aligned with #, otherwise indent comments normally. These
+  // tests cannot use verifyFormat because messUp manipulates leading
+  // whitespace.
+  {
+    const char *Expected = ""
+                           "void f() {\n"
+                           "#if 1\n"
+                           "// Preprocessor aligned.\n"
+                           "#  define A 0\n"
+                           "  // Code. Separated by blank line.\n"
+                           "\n"
+                           "#  define B 0\n"
+                           "  // Code. Not aligned with #\n"
+                           "#  define C 0\n"
+                           "#endif";
+    const char *ToFormat = ""
+                           "void f() {\n"
+                           "#if 1\n"
+                           "// Preprocessor aligned.\n"
+                           "#  define A 0\n"
+                           "// Code. Separated by blank line.\n"
+                           "\n"
+                           "#  define B 0\n"
+                           "   // Code. Not aligned with #\n"
+                           "#  define C 0\n"
+                           "#endif";
+    EXPECT_EQ(Expected, format(ToFormat, Style));
+    EXPECT_EQ(Expected, format(Expected, Style));
+  }
+  // Keep block quotes aligned.
+  {
+    const char *Expected = ""
+                           "void f() {\n"
+                           "#if 1\n"
+                           "/* Preprocessor aligned. */\n"
+                           "#  define A 0\n"
+                           "  /* Code. Separated by blank line. */\n"
+                           "\n"
+                           "#  define B 0\n"
+                           "  /* Code. Not aligned with # */\n"
+                           "#  define C 0\n"
+                           "#endif";
+    const char *ToFormat = ""
+                           "void f() {\n"
+                           "#if 1\n"
+                           "/* Preprocessor aligned. */\n"
+                           "#  define A 0\n"
+                           "/* Code. Separated by blank line. */\n"
+                           "\n"
+                           "#  define B 0\n"
+                           "   /* Code. Not aligned with # */\n"
+                           "#  define C 0\n"
+                           "#endif";
+    EXPECT_EQ(Expected, format(ToFormat, Style));
+    EXPECT_EQ(Expected, format(Expected, Style));
+  }
+  // Keep comments aligned with un-indented directives.
+  {
+    const char *Expected = ""
+                           "void f() {\n"
+                           "// Preprocessor aligned.\n"
+                           "#define A 0\n"
+                           "  // Code. Separated by blank line.\n"
+                           "\n"
+                           "#define B 0\n"
+                           "  // Code. Not aligned with #\n"
+                           "#define C 0\n";
+    const char *ToFormat = ""
+                           "void f() {\n"
+                           "// Preprocessor aligned.\n"
+                           "#define A 0\n"
+                           "// Code. Separated by blank line.\n"
+                           "\n"
+                           "#define B 0\n"
+                           "   // Code. Not aligned with #\n"
+                           "#define C 0\n";
+    EXPECT_EQ(Expected, format(ToFormat, Style));
+    EXPECT_EQ(Expected, format(Expected, Style));
+  }
   // Test with tabs.
   Style.UseTab = FormatStyle::UT_Always;
   Style.IndentWidth = 8;