make deinitializeDMD reset onlyOneMain check

compiler/src/dmd/frontend.d

@@ -175,6 +175,7 @@ void deinitializeDMD()
     import dmd.dsymbol : Dsymbol;
     import dmd.escape : EscapeState;
     import dmd.expression : Expression;
+    import dmd.func : FuncDeclaration;
     import dmd.globals : global;
     import dmd.id : Id;
     import dmd.mtype : Type;
@@ -184,6 +185,7 @@ void deinitializeDMD()
 
     diagnosticHandler = null;
     fatalErrorHandler = null;
+    FuncDeclaration.lastMain = null;
 
     global.deinitialize();
 

compiler/src/dmd/frontend.h

@@ -3668,6 +3668,7 @@ class FuncDeclaration : public Declaration
     bool requiresClosure;
     Array<VarDeclaration* > closureVars;
     Array<VarDeclaration* > outerVars;
+    static FuncDeclaration* lastMain;
     Array<FuncDeclaration* > siblingCallers;
     Array<FuncDeclaration* >* inlinedNestedCallees;
     AttributeViolation* safetyViolation;
@@ -7406,6 +7407,8 @@ class NrvoWalker final : public StatementRewriteWalker
     void visit(TryFinallyStatement* s) override;
 };
 
+extern bool onlyOneMain(FuncDeclaration* fd);
+
 class NOGCVisitor final : public StoppableVisitor
 {
 public:

compiler/src/dmd/func.d

@@ -269,6 +269,10 @@ extern (C++) class FuncDeclaration : Declaration
      */
     VarDeclarations outerVars;
 
+    // Most recent encountered `main` (`WinMain` or `DllMain`) function.
+    // Track it to give error messages for multiple entrypoints
+    __gshared FuncDeclaration lastMain;
+
     /// Sibling nested functions which called this one
     FuncDeclarations siblingCallers;
 

compiler/src/dmd/funcsem.d

@@ -154,6 +154,28 @@
     }
 }
 
+/****************************************
+ * Only one entry point function is allowed. Print error if more than one.
+ * Params:
+ *      fd = a "main" function
+ * Returns:
+ *      true if haven't seen "main" before
+ */
+extern (C++) bool onlyOneMain(FuncDeclaration fd)
+{
+    if (auto lastMain = FuncDeclaration.lastMain)
+    {
+        const format = (target.os == Target.OS.Windows)
+            ? "only one entry point `main`, `WinMain` or `DllMain` is allowed"
+            : "only one entry point `main` is allowed";
+        error(fd.loc, format.ptr);
+        errorSupplemental(lastMain.loc, "previously found `%s` here", lastMain.toFullSignature());
+        return false;
+    }
+    FuncDeclaration.lastMain = fd;
+    return true;
+}
+
 /**********************************
  * Main semantic routine for functions.
  */

compiler/src/dmd/glue.d

@@ -52,6 +52,7 @@ import dmd.e2ir;
 import dmd.errors;
 import dmd.expression;
 import dmd.func;
+import dmd.funcsem : onlyOneMain;
 import dmd.globals;
 import dmd.identifier;
 import dmd.id;
@@ -1623,29 +1624,6 @@ private bool entryPointFunctions(Obj objmod, FuncDeclaration fd)
     return false;
 }
 
-/****************************************
- * Only one entry point function is allowed. Print error if more than one.
- * Params:
- *      fd = a "main" function
- * Returns:
- *      true if haven't seen "main" before
- */
-private bool onlyOneMain(FuncDeclaration fd)
-{
-    __gshared FuncDeclaration lastMain;
-    if (lastMain)
-    {
-        const format = (target.os == Target.OS.Windows)
-            ? "only one entry point `main`, `WinMain` or `DllMain` is allowed"
-            : "only one entry point `main` is allowed";
-        error(fd.loc, format.ptr);
-        errorSupplemental(lastMain.loc, "previously found `%s` here", lastMain.toFullSignature());
-        return false;
-    }
-    lastMain = fd;
-    return true;
-}
-
 /* ================================================================== */
 
 /**************************************