[clang] [clang-format] Properly indent lines inside Verilog case structure (PR #65861)

[via cfe-commits]

llvmbot wrote:

@llvm/pr-subscribers-clang-format

<details>
<summary>Changes</summary>

When a statement following a case label had to be broken into multiple lines, the continuation parts were not indented correctly.

Old:

```Verilog
case (data)
  16'd0:
    result = // break here
    10'b0111111111;
endcase
```

New:

```Verilog
case (data)
  16'd0:
    result = // break here
        10'b0111111111;
endcase
```

Verilog case labels and the following statements are on the same unwrapped line due to the difficulty of identifying them.  So there was a rule in `getNewLineColumn` to add a level of indentation to the part following the case label.  However, in case the line had to be broken again, the code at the end of the function would see that the line was already broken with the continuation part indented, so it would not indent it more.  Now `State.FirstIndent` is changed as well for the part following the case label, so the logic for determining when to add a continuation indentation works.
--
Full diff: https://github.com/llvm/llvm-project/pull/65861.diff

2 Files Affected:

- (modified) clang/lib/Format/ContinuationIndenter.cpp (+16-6) 
- (modified) clang/unittests/Format/FormatTestVerilog.cpp (+47) 


<pre>
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index ac62dab1b07cdca..ec21c181772fa81 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -1204,12 +1204,13 @@ unsigned ContinuationIndenter::getNewLineColumn(const LineState &State) {
                     CurrentState.Indent + Style.ContinuationIndentWidth);
   }
 
-  // After a goto label. Usually labels are on separate lines. However
-  // for Verilog the labels may be only recognized by the annotator and
-  // thus are on the same line as the current token.
-  if ((Style.isVerilog() && Keywords.isVerilogEndOfLabel(Previous)) ||
-      (Style.BreakBeforeBraces == FormatStyle::BS_Whitesmiths &&
-       State.Line->First->is(tok::kw_enum))) {
+  // Indentation of the statement following a Verilog case label is taken care
+  // of in moveStateToNextToken.
+  if (Style.isVerilog() && Keywords.isVerilogEndOfLabel(Previous))
+    return State.FirstIndent;
+
+  if (Style.BreakBeforeBraces == FormatStyle::BS_Whitesmiths &&
+      State.Line->First->is(tok::kw_enum)) {
     return (Style.IndentWidth * State.Line->First->IndentLevel) +
            Style.IndentWidth;
   }
@@ -1599,6 +1600,15 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
 
   State.Column += Current.ColumnWidth;
   State.NextToken = State.NextToken->Next;
+  // Verilog case labels are are on the same unwrapped lines as the statements
+  // that follow.  TokenAnnotator identifies them and sets MustBreakBefore.
+  // Indentation is taken care of here.  A case label can only have 1 statement
+  // in Verilog, so we don't have to worry about lines that follow.
+  if (Style.isVerilog() && State.NextToken &&
+      State.NextToken->MustBreakBefore &&
+      Keywords.isVerilogEndOfLabel(Current)) {
+    State.FirstIndent += Style.IndentWidth;
+  }
 
   unsigned Penalty =
       handleEndOfLine(Current, State, DryRun, AllowBreak, Newline);
diff --git a/clang/unittests/Format/FormatTestVerilog.cpp b/clang/unittests/Format/FormatTestVerilog.cpp
index 9b090aa74f714d1..7161312126ea6ed 100644
--- a/clang/unittests/Format/FormatTestVerilog.cpp
+++ b/clang/unittests/Format/FormatTestVerilog.cpp
@@ -312,6 +312,53 @@ TEST_F(FormatTestVerilog, Case) {
   verifyFormat("default:\n"
                "  x = '{x: x, default: 9};\n",
                Style);
+  // When the line following the case label needs to be indented, the
+  // continuation should be indented correctly.
+  verifyFormat("case (data)\n"
+               "  16'd0:\n"
+               "    result = //\n"
+               "        10'b0111111111;\n"
+               "endcase");
+  verifyFormat("case (data)\n"
+               "  16'd0, //\n"
+               "      16'd1:\n"
+               "    result = //\n"
+               "        10'b0111111111;\n"
+               "endcase");
+  verifyFormat("case (data)\n"
+               "  16'd0:\n"
+               "    result = (10'b0111111111 + //\n"
+               "              10'b0111111111 + //\n"
+               "              10'b0111111111);\n"
+               "endcase");
+  verifyFormat("case (data)\n"
+               "  16'd0:\n"
+               "    result =              //\n"
+               "        (10'b0111111111 + //\n"
+               "         10'b0111111111 + //\n"
+               "         10'b0111111111);\n"
+               "endcase");
+  verifyFormat("case (data)\n"
+               "  16'd0:\n"
+               "    result =          //\n"
+               "        longfunction( //\n"
+               "            arg);\n"
+               "endcase");
+  Style = getDefaultStyle();
+  Style.ContinuationIndentWidth = 1;
+  verifyFormat("case (data)\n"
+               "  16'd0:\n"
+               "    result = //\n"
+               "     10'b0111111111;\n"
+               "endcase",
+               Style);
+  verifyFormat("case (data)\n"
+               "  16'd0:\n"
+               "    result =       //\n"
+               "     longfunction( //\n"
+               "      arg);\n"
+               "endcase",
+               Style);
 }
 
 TEST_F(FormatTestVerilog, Coverage) {
</pre>

</details>

https://github.com/llvm/llvm-project/pull/65861