caio/clang-p2996
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[clang-format] Fix alignment in #else preprocessor blocks

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Summary:
clang-format makes multiple passes when #if/#else preprocessor blocks are found.  It will make
one pass for normal code and code in the #if block, and then it will make another pass for just
the code in #else blocks. This often results in invalid alignment inside the else blocks because
they do not have any scope or indentAndNestingLevel context from their surrounding tokens/lines.

This patch remedies that by caching any initial indentAndNestingLevel from a second pass and
not breaking/returning early when a scope change is detected.

Fixes #36070

Reviewers: HazardyKnusperkeks, MyDeveloperDay

Tags: clang, clang-format

Differential Revision: https://reviews.llvm.org/D134042
This commit is contained in:
mitchell
2022-09-27 15:40:39 -04:00
parent 670cac7280
commit c0779756a0
2 changed files with 112 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
clang/lib/Format/WhitespaceManager.cpp
View File

@@ -522,6 +522,13 @@ static unsigned AlignTokens(const FormatStyle &Style, F &&Matches,
? Changes[StartAt].indentAndNestingLevel()
: std::tuple<unsigned, unsigned, unsigned>();
// Keep track if the first token has a non-zero indent and nesting level.
// This can happen when aligning the contents of "#else" preprocessor blocks,
// which is done separately.
bool HasInitialIndentAndNesting =
StartAt == 0 &&
IndentAndNestingLevel > std::tuple<unsigned, unsigned, unsigned>();
// Keep track of the number of commas before the matching tokens, we will only
// align a sequence of matching tokens if they are preceded by the same number
// of commas.
@@ -556,8 +563,19 @@ static unsigned AlignTokens(const FormatStyle &Style, F &&Matches,
unsigned i = StartAt;
for (unsigned e = Changes.size(); i != e; ++i) {
if (Changes[i].indentAndNestingLevel() < IndentAndNestingLevel)
break;
if (Changes[i].indentAndNestingLevel() < IndentAndNestingLevel) {
if (!HasInitialIndentAndNesting)
break;
// The contents of preprocessor blocks are aligned separately.
// If the initial preprocessor block is indented or nested (e.g. it's in
// a function), do not align and exit after finishing this scope block.
// Instead, align, and then lower the baseline indent and nesting level
// in order to continue aligning subsequent blocks.
EndOfSequence = i;
AlignCurrentSequence();
IndentAndNestingLevel =
Changes[i].indentAndNestingLevel(); // new baseline
}
if (Changes[i].NewlinesBefore != 0) {
CommasBeforeMatch = 0;

92
clang/unittests/Format/FormatTest.cpp
View File

@@ -5825,6 +5825,98 @@ TEST_F(FormatTest, IndentPreprocessorDirectives) {
Style);
}
TEST_F(FormatTest, FormatAlignInsidePreprocessorElseBlock) {
FormatStyle Style = getLLVMStyle();
Style.AlignConsecutiveAssignments.Enabled = true;
Style.AlignConsecutiveDeclarations.Enabled = true;
// Test with just #if blocks.
verifyFormat("void f1() {\n"
"#if 1\n"
" int foo = 1;\n"
" int foobar = 2;\n"
"#endif\n"
"}\n"
"#if 1\n"
"int baz = 3;\n"
"#endif\n"
"void f2() {\n"
"#if 1\n"
" char *foobarbaz = \"foobarbaz\";\n"
" int quux = 4;\n"
"}",
Style);
// Test with just #else blocks.
verifyFormat("void f1() {\n"
"#if 1\n"
"#else\n"
" int foo = 1;\n"
" int foobar = 2;\n"
"#endif\n"
"}\n"
"#if 1\n"
"#else\n"
"int baz = 3;\n"
"#endif\n"
"void f2() {\n"
"#if 1\n"
"#else\n"
" char *foobarbaz = \"foobarbaz\";\n"
" int quux = 4;\n"
"}",
Style);
// Test with a mix of #if and #else blocks.
verifyFormat("void f1() {\n"
"#if 1\n"
"#else\n"
" int foo = 1;\n"
" int foobar = 2;\n"
"#endif\n"
"}\n"
"#if 1\n"
"int baz = 3;\n"
"#endif\n"
"void f2() {\n"
"#if 1\n"
"#else\n"
" // prevent alignment with #else in f1\n"
" char *foobarbaz = \"foobarbaz\";\n"
" int quux = 4;\n"
"}",
Style);
// Test with nested #if and #else blocks.
verifyFormat("void f1() {\n"
"#if 1\n"
"#else\n"
"#if 2\n"
"#else\n"
" int foo = 1;\n"
" int foobar = 2;\n"
"#endif\n"
"#endif\n"
"}\n"
"#if 1\n"
"#else\n"
"#if 2\n"
"int baz = 3;\n"
"#endif\n"
"#endif\n"
"void f2() {\n"
"#if 1\n"
"#if 2\n"
"#else\n"
" // prevent alignment with #else in f1\n"
" char *foobarbaz = \"foobarbaz\";\n"
" int quux = 4;\n"
"#endif\n"
"#endif\n"
"}",
Style);
}
TEST_F(FormatTest, FormatHashIfNotAtStartOfLine) {
verifyFormat("{\n { a #c; }\n}");
}