[clang] [Clang] Wide delimiters ('{{{') for expect strings (PR #77326)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: None (sethp)

<details>
<summary>Changes</summary>

Prior to this commit, it was impossible to use the simple string matching directives to look for most content that contains `{{`, such as:

```
// expected-note {{my_struct{{1}, 2}}}
```

Which would parse like so:

```
             "nested" brace v
// expected-note {{my_struct{{1}, 2}}}
          closes the nested brace  ^ |
                            trailing }
```

And the frontend would complain 'cannot find end ('}}') of expected'.

At this snapshot, VerifyDiagnosticConsumer's parser now counts the opening braces and looks for a matching length of closing sigils, allowing the above to be written as:

```
// expected-note {{{my_struct{{1}, 2}}}}
   opening brace |-|                 |-|
  closing brace is '}}}', found here ^
```

This came about as a result of this discussion: https://github.com/llvm/llvm-project/pull/74852#discussion_r1443117644

cc @<!-- -->erichkeane 

---
Full diff: https://github.com/llvm/llvm-project/pull/77326.diff


2 Files Affected:

- (modified) clang/include/clang/Basic/DiagnosticFrontendKinds.td (+1-1) 
- (modified) clang/lib/Frontend/VerifyDiagnosticConsumer.cpp (+11-4) 


``````````diff
diff --git a/clang/include/clang/Basic/DiagnosticFrontendKinds.td b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
index 715e0c0dc8fa84..4bf0ab54a046c1 100644
--- a/clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -166,7 +166,7 @@ def err_verify_no_such_marker : Error<
 def err_verify_missing_start : Error<
     "cannot find start ('{{') of expected %0">;
 def err_verify_missing_end : Error<
-    "cannot find end ('}}') of expected %0">;
+    "cannot find end ('%1') of expected %0">;
 def err_verify_invalid_content : Error<
     "invalid expected %0: %1">;
 def err_verify_missing_regex : Error<
diff --git a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
index ab8174f4f4db92..5eab7bd3619f19 100644
--- a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
+++ b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
@@ -612,12 +612,19 @@ static bool ParseDirective(StringRef S, ExpectedData *ED, SourceManager &SM,
                    diag::err_verify_missing_start) << KindStr;
       continue;
     }
+    llvm::SmallString<8> CloseBrace("}}");
+    const char *const DelimBegin = PH.C;
     PH.Advance();
+    // Count the number of opening braces for `string` kinds
+    for (; !D.RegexKind && PH.Next("{"); PH.Advance())
+      CloseBrace += '}';
     const char* const ContentBegin = PH.C; // mark content begin
-    // Search for token: }}
-    if (!PH.SearchClosingBrace("{{", "}}")) {
-      Diags.Report(Pos.getLocWithOffset(PH.C-PH.Begin),
-                   diag::err_verify_missing_end) << KindStr;
+    // Search for closing brace
+    StringRef OpenBrace(DelimBegin, ContentBegin - DelimBegin);
+    if (!PH.SearchClosingBrace(OpenBrace, CloseBrace)) {
+      Diags.Report(Pos.getLocWithOffset(PH.C - PH.Begin),
+                   diag::err_verify_missing_end)
+          << KindStr << CloseBrace;
       continue;
     }
     const char* const ContentEnd = PH.P; // mark content end

``````````

</details>


https://github.com/llvm/llvm-project/pull/77326