[clang-tools-extra] [clang-doc] Add regression test for test comments in macros (PR #132510)

[via cfe-commits]

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+// Fixes #59819. The underlying problem was fixed in https://reviews.llvm.org/D142560, but this patch adds a proper regression test.
+// RUN: rm -rf %t && mkdir -p %t
+// RUN: clang-doc --format=md --doxygen --output=%t --executor=standalone %s
+// RUN: FileCheck %s < %t/GlobalNamespace/MyClass.md --check-prefix=MD-MYCLASS-LINE
+// RUN: FileCheck %s < %t/GlobalNamespace/MyClass.md --check-prefix=MD-MYCLASS
+// RUN: clang-doc --format=html --doxygen --output=%t --executor=standalone %s
+// RUN: FileCheck %s < %t/GlobalNamespace/MyClass.html --check-prefix=HTML-MYCLASS-LINE
+// RUN: FileCheck %s < %t/GlobalNamespace/MyClass.html --check-prefix=HTML-MYCLASS
+
+#define DECLARE_METHODS                                           \
+    /**   							  \
+     * @brief Declare a method to calculate the sum of two numbers\
+     */                                                           \
+    int Add(int a, int b)                                         \
+    {                                                             \
+        return a + b;                                             \
+    }
+
+// MD-MYCLASS: ### Add
+// MD-MYCLASS: *public int Add(int a, int b)*
+// MD-MYCLASS: **brief** Declare a method to calculate the sum of two numbers
+
+// HTML-MYCLASS: <p>public int Add(int a, int b)</p>
+// HTML-MYCLASS: <div>brief</div>
+// HTML-MYCLASS: <p> Declare a method to calculate the sum of two numbers</p>
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ZhongUncle wrote:

I also have another problem: Why HTML match is not similar to Markdown?

Because I refer to `enum.cpp` to write this match. It matchs different parts. So I don't make sense which part must match in HTML.

Markdown match is clearly, HTML seem to ignore something.

https://github.com/llvm/llvm-project/pull/132510