[clang-tools-extra] [clang-tidy] Add new check bugprone-tagged-union-member-count (PR #89925)

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=?utf-8?b?R8OhYm9yIFTDs3RodsOhcmk=?= <tigbrcode at protonmail.com>
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In-Reply-To: <llvm.org/llvm/llvm-project/pull/89925 at github.com>


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@@ -0,0 +1,150 @@
+// RUN: %check_clang_tidy -std=c++98-or-later %s bugprone-tagged-union-member-count %t \
+// RUN:   -config='{CheckOptions: { \
+// RUN:     bugprone-tagged-union-member-count.StrictMode: 1, \
+// RUN:     bugprone-tagged-union-member-count.EnumCounterHeuristicIsEnabled: 0, \
+// RUN:     bugprone-tagged-union-member-count.EnumCounterSuffix: "count", \
+// RUN:  }}' --
+
+typedef enum tags3 {
+	tags3_1,
+	tags3_2,
+	tags3_3,
+} tags3;
+
+typedef enum tags4 {
+	tags4_1,
+	tags4_2,
+	tags4_3,
+	tags4_4,
+} tags4;
+
+typedef enum tags5 {
+	tags5_1,
+	tags5_2,
+	tags5_3,
+	tags5_4,
+	tags5_5,
+} tags5;
+
+enum class classtags3 {
+	classtags3_1,
+	classtags3_2,
+	classtags3_3,
+};
+
+enum class classtags4 {
+	classtags4_1,
+	classtags4_2,
+	classtags4_3,
+	classtags4_4,
+};
+
+enum class classtags5 {
+	classtags5_1,
+	classtags5_2,
+	classtags5_3,
+	classtags5_4,
+	classtags5_5,
+};
+
+enum class typedtags3 : unsigned int {
+	typedtags3_1,
+	typedtags3_2,
+	typedtags3_3,
+};
+
+enum class typedtags4 : long {
+	typedtags4_1,
+	typedtags4_2,
+	typedtags4_3,
+	typedtags4_4,
+};
+
+enum class typedtags5 {
+	typedtags5_1,
+	typedtags5_2,
+	typedtags5_3,
+	typedtags5_4,
+	typedtags5_5,
+};
+
+typedef union union3 {
+	short *shorts;
+	int *ints;
+	float *floats;
+} union3;
+
+typedef union union4 {
+	short *shorts;
+	double *doubles;
+	int *ints;
+	float *floats;
+} union4;
+
+// Technically this means that every enum value is defined from 0-256 and therefore a warning is given.
+enum mycolor {
+	mycolor_black = 0x00,
+	mycolor_gray  = 0xcc,
+	mycolor_white = 0xff,
+};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:8: warning: Tagged union has fewer data members (3) than tags (256)! [bugprone-tagged-union-member-count]
+struct taggedunion9 { 
+	enum mycolor tag;
+	union {
+		int a;
+		float b;
+		struct {
+			double re;
+			double im;
+		} complex;
+	} data;
+};
+
+// CHECK-MESSAGES: :[[@LINE+1]]:8: warning: Tagged union has fewer data members (3) than tags (4)! [bugprone-tagged-union-member-count]
----------------
whisperity wrote:

```suggestion
// CHECK-MESSAGES: :[[@LINE+1]]:8: warning: Tagged union has fewer data members (3) than tags (4)
```

There is no need to repeat the full message in every line, as the check is applied as a substring and regular expression match, it is enough to type out the prefix only until the last dynamically generated part.

https://github.com/llvm/llvm-project/pull/89925