[clang] [clang-format] Don't confuse initializer equal signs in for loops (PR #77712)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-format

Author: Emilia Kond (rymiel)

<details>
<summary>Changes</summary>

clang-format has logic to align declarations of multiple variables of the same type, aligning them at the equals sign. This logic is applied in for loops as well. However, this alignment logic also erroneously affected the equals signs of designated initializers.

This patch forbids alignment if the token 2 tokens back from the equals sign is a designated initializer period.

Fixes https://github.com/llvm/llvm-project/issues/73902

---
Full diff: https://github.com/llvm/llvm-project/pull/77712.diff


2 Files Affected:

- (modified) clang/lib/Format/ContinuationIndenter.cpp (+3-1) 
- (modified) clang/unittests/Format/FormatTest.cpp (+12) 


``````````diff
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 102504182c4505..ce6c17c3b7d927 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -703,7 +703,9 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
 
   if (Current.is(tok::equal) &&
       (State.Line->First->is(tok::kw_for) || Current.NestingLevel == 0) &&
-      CurrentState.VariablePos == 0) {
+      CurrentState.VariablePos == 0 &&
+      (!Previous.Previous ||
+       Previous.Previous->isNot(TT_DesignatedInitializerPeriod))) {
     CurrentState.VariablePos = State.Column;
     // Move over * and & if they are bound to the variable name.
     const FormatToken *Tok = &Previous;
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 25ef5c680af862..01678a4971caae 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -4944,6 +4944,18 @@ TEST_F(FormatTest, DesignatedInitializers) {
                "    [3] = cccccccccccccccccccccccccccccccccccccc,\n"
                "    [4] = dddddddddddddddddddddddddddddddddddddd,\n"
                "    [5] = eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee};");
+
+  verifyFormat("for (const TestCase &test_case : {\n"
+               "         TestCase{\n"
+               "             .a = 1,\n"
+               "             .b = 1,\n"
+               "         },\n"
+               "         TestCase{\n"
+               "             .a = 2,\n"
+               "             .b = 2,\n"
+               "         },\n"
+               "     }) {\n"
+               "}\n");
 }
 
 TEST_F(FormatTest, BracedInitializerIndentWidth) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/77712