feat(errorprone): enforce no-java.lang.Math rule at compile time

Replace the regex-based .github/workflows/math-check.yml scan with a
custom ErrorProne BugChecker (ForbidJavaLangMath) in the :errorprone
module. It resolves symbols on the type-attributed AST, so it catches
every usage form (direct, fully-qualified, statically-imported,
method references, field access) with no string/comment false
positives. java.lang.StrictMath remains allowed.

- add ForbidJavaLangMath BugChecker (auto-registered via @autoservice)
- enable -Xep:ForbidJavaLangMath:ERROR in build.gradle
- exempt the canonical x86 MathWrapper via @SuppressWarnings
- delete .github/workflows/math-check.yml

Note: ErrorProne runs only on JDK 11+, so the rule is no longer
enforced on the JDK 8 (x86_64) build path.

Author: halibobo1205

.github/workflows/math-check.yml

@@ -130,6 +130,7 @@ subprojects {
                 errorproneArgs.addAll([
                         '-Xep:StringCaseLocaleUsage:ERROR',
                         '-Xep:StringCaseLocaleUsageMethodRef:ERROR',
+                        '-Xep:ForbidJavaLangMath:ERROR',
                 ])
             }
         }

build.gradle

@@ -0,0 +1,106 @@
+package errorprone;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.IdentifierTree;
+import com.sun.source.tree.MemberReferenceTree;
+import com.sun.source.tree.MemberSelectTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.code.Symbol;
+
+/**
+ * Forbids any direct use of {@code java.lang.Math}.
+ *
+ * <p>{@code java.lang.Math} permits the JIT to use platform-specific intrinsics for some
+ * methods (notably the transcendental and floating-point ones), so results are not
+ * guaranteed to be bit-for-bit identical across CPUs / JVMs. In a consensus system that
+ * non-determinism can fork the chain. All math must therefore go through
+ * {@code org.tron.common.math.StrictMathWrapper}, which is backed by {@code java.lang.StrictMath}
+ * and produces reproducible results.
+ *
+ * <p>This checker replaces the previous regex-based {@code .github/workflows/math-check.yml}
+ * scan. It resolves symbols on the type-attributed AST, so it has no false positives from
+ * strings/comments or unrelated classes named {@code Math}, and it catches every usage form:
+ * <ul>
+ *   <li>direct calls: {@code Math.max(a, b)}</li>
+ *   <li>fully-qualified calls: {@code java.lang.Math.max(a, b)}</li>
+ *   <li>statically-imported calls: {@code import static java.lang.Math.max; ... max(a, b)}</li>
+ *   <li>method references: {@code Math::max}</li>
+ *   <li>field access: {@code Math.PI}, {@code Math.E}</li>
+ *   <li>statically-imported fields used bare: {@code import static java.lang.Math.PI; ... PI}</li>
+ * </ul>
+ *
+ * <p>{@code java.lang.StrictMath} itself is intentionally allowed — it is the deterministic
+ * primitive that {@code StrictMathWrapper} and the deprecated {@code MathWrapper} are built on.
+ * Those wrappers legitimately call {@code java.lang.Math}/{@code StrictMath} and are exempted via
+ * {@code @SuppressWarnings("ForbidJavaLangMath")}.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    name = "ForbidJavaLangMath",
+    summary = "Direct use of java.lang.Math is forbidden: its results are not guaranteed to be "
+        + "bit-for-bit identical across platforms, which can break consensus. Use "
+        + "org.tron.common.math.StrictMathWrapper instead.",
+    severity = BugPattern.SeverityLevel.ERROR
+)
+public class ForbidJavaLangMath extends BugChecker
+    implements BugChecker.MethodInvocationTreeMatcher,
+        BugChecker.MemberReferenceTreeMatcher,
+        BugChecker.MemberSelectTreeMatcher,
+        BugChecker.IdentifierTreeMatcher {
+
+  private static final String JAVA_LANG_MATH = "java.lang.Math";
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    return flagIfMathMember(ASTHelpers.getSymbol(tree), tree);
+  }
+
+  @Override
+  public Description matchMemberReference(MemberReferenceTree tree, VisitorState state) {
+    return flagIfMathMember(ASTHelpers.getSymbol(tree), tree);
+  }
+
+  @Override
+  public Description matchMemberSelect(MemberSelectTree tree, VisitorState state) {
+    // Method selects (Math.max) are already reported via matchMethodInvocation /
+    // matchMemberReference; only flag field selects (Math.PI, Math.E) here to avoid
+    // double-reporting the same usage.
+    Symbol sym = ASTHelpers.getSymbol(tree);
+    if (!(sym instanceof Symbol.VarSymbol)) {
+      return Description.NO_MATCH;
+    }
+    return flagIfMathMember(sym, tree);
+  }
+
+  @Override
+  public Description matchIdentifier(IdentifierTree tree, VisitorState state) {
+    // Catches statically-imported constants referenced bare (e.g. `import static
+    // java.lang.Math.PI; ... double c = PI;`). Statically-imported *methods* are caught by
+    // matchMethodInvocation, so restrict this to fields to avoid double-reporting.
+    Symbol sym = ASTHelpers.getSymbol(tree);
+    if (!(sym instanceof Symbol.VarSymbol)) {
+      return Description.NO_MATCH;
+    }
+    return flagIfMathMember(sym, tree);
+  }
+
+  private Description flagIfMathMember(Symbol sym, Tree tree) {
+    if (sym == null) {
+      return Description.NO_MATCH;
+    }
+    Symbol.ClassSymbol enclosingClass = ASTHelpers.enclosingClass(sym);
+    if (enclosingClass == null) {
+      return Description.NO_MATCH;
+    }
+    if (enclosingClass.getQualifiedName().contentEquals(JAVA_LANG_MATH)) {
+      return describeMatch(tree);
+    }
+    return Description.NO_MATCH;
+  }
+}

errorprone/src/main/java/errorprone/ForbidJavaLangMath.java

@@ -6,6 +6,7 @@
  * especially for floating-point calculations.
  */
 @Deprecated
+@SuppressWarnings("ForbidJavaLangMath") // canonical wrapper: deliberately delegates to java.lang.Math
 public class MathWrapper {
 
   public static double pow(double a, double b) {