[style.alias_syntax] Add AutoFix replacement

Author: ntrel

src/dscanner/analysis/alias_syntax_check.d

@@ -25,13 +25,64 @@ final class AliasSyntaxCheck : BaseAnalyzer
 
 	override void visit(const AliasDeclaration ad)
 	{
+		// new alias syntax uses `ad.initializers` instead
 		if (ad.declaratorIdentifierList is null)
 			return;
 		assert(ad.declaratorIdentifierList.identifiers.length > 0,
 				"Identifier list length is zero, libdparse has a bug");
+
+		static string tokenStr(const Token[] tokens)
+		{
+			string r;
+			foreach (i, t; tokens)
+			{
+				if (i)
+				{
+					// keep whitespace to separate multiple tokens like original
+					foreach (tt; tokens[i - 1].trailingTrivia)
+						r ~= tt.text;
+				}
+				foreach (lt; t.leadingTrivia)
+					r ~= lt.text;
+
+				string st = t.text ? t.text : t.type.str;
+				assert(st.length);
+				r ~= st;
+			}
+			return r;
+		}
+		// `alias storage target ident, ident2;`
+		string target;
+		foreach (i, sc; ad.storageClasses)
+		{
+			target ~= tokenStr(sc.tokens);
+			target ~= ' ';
+		}
+		target ~= tokenStr(ad.type.tokens);
+		// or single function type:
+		// `alias storage type ident(params) attributes;`
+		if (ad.parameters)
+		{
+			target ~= tokenStr(ad.parameters.tokens);
+			foreach (fa; ad.memberFunctionAttributes)
+			{
+				target ~= ' ';
+				target ~= tokenStr(fa.tokens);
+			}
+		}
+		// need `ident = target, ident2 = target`
+		string rep;
+		foreach (i, t; ad.declaratorIdentifierList.identifiers)
+		{
+			if (i)
+				rep ~= ", ";
+			rep ~= t.text ~ " = " ~ target;
+		}
 		addErrorMessage(ad, KEY,
 				"Prefer the new \"'alias' identifier '=' type ';'\" syntax"
-				~ " to the  old \"'alias' type identifier ';'\" syntax.");
+				~ " to the old \"'alias' type identifier ';'\" syntax.",
+				[AutoFix.replacement(ad.tokens[1 .. $ - 1], rep,
+					"Rewrite alias to use assignment syntax")]);
 	}
 
 private:
@@ -40,16 +91,37 @@ private:
 
 unittest
 {
-	import dscanner.analysis.helpers : assertAnalyzerWarnings;
+	import dscanner.analysis.helpers : assertAnalyzerWarnings, assertAutoFix;
 	import dscanner.analysis.config : StaticAnalysisConfig, Check, disabledConfig;
 	import std.stdio : stderr;
 
 	StaticAnalysisConfig sac = disabledConfig();
 	sac.alias_syntax_check = Check.enabled;
 	assertAnalyzerWarnings(q{
 		alias int abcde; /+
-		^^^^^^^^^^^^^^^^ [warn]: Prefer the new "'alias' identifier '=' type ';'" syntax to the  old "'alias' type identifier ';'" syntax.+/
+		^^^^^^^^^^^^^^^^ [warn]: Prefer the new "'alias' identifier '=' type ';'" syntax to the old "'alias' type identifier ';'" syntax.+/
 		alias abcde = int;
+		alias xyz[] a, b; /+
+		^^^^^^^^^^^^^^^^^ [warn]: Prefer the new "'alias' identifier '=' type ';'" syntax to the old "'alias' type identifier ';'" syntax.+/
+		alias a = xyz, b = xyz;
+		alias void Func(); /+
+		^^^^^^^^^^^^^^^^^^ [warn]: Prefer the new "'alias' identifier '=' type ';'" syntax to the old "'alias' type identifier ';'" syntax.+/
+		alias Func = void();
+		alias tem(T) = T!int;
+	}c, sac);
+
+	assertAutoFix(q{
+		alias T * PT; // fix
+		alias int[f(1, 2) + 3] sa; // fix
+		alias void Func(int i) pure @att(4 * 5.g); // fix
+		alias extern (C) void function() FP; // fix
+		alias xyz a, b; // fix
+	}c, q{
+		alias PT = T *; // fix
+		alias sa = int[f(1, 2) + 3]; // fix
+		alias Func = void(int i) pure @att(4 * 5.g); // fix
+		alias FP = extern (C) void function(); // fix
+		alias a = xyz, b = xyz; // fix
 	}c, sac);
 
 	stderr.writeln("Unittest for AliasSyntaxCheck passed.");