diff --git a/changelog/dmd.basic-vs-primary-type.dd b/changelog/dmd.basic-vs-primary-type.dd
new file mode 100644
index 000000000000..91e792020171
--- /dev/null
+++ b/changelog/dmd.basic-vs-primary-type.dd
@@ -0,0 +1,13 @@
+The term *basic type* is now *primary type*
+
+The parser now uses the term *primary type* for what used to be referred to as *basic type.*
+The term *basic type* is used specifically for type expressions that are not immediately recursive.
+
+A *basic type* is a *fundamental type* (those which have keywords)
+or a type given by an identifier, a `typeof`, a `mixin`, or a `__traits`.
+Absent from this list are `__vector` types and types spelled out using a qualifier and parentheses (e.g. `const(int)`).
+
+A *primary type* is a *basic type* or a `__vector` type or a qualified type.
+
+For the most part, *primary type* is the term you want to use and will see in error messages now.
+There are some corners where indeed a *basic type* is required.
diff --git a/changelog/dmd.const-base.dd b/changelog/dmd.const-base.dd
new file mode 100644
index 000000000000..adcfe3f527a2
--- /dev/null
+++ b/changelog/dmd.const-base.dd
@@ -0,0 +1,18 @@
+Specifying a qualified type as a base class or interface is an error now
+
+A type like `const(Object)` could be used as a base class in the base class list
+of a class or interface declaration or of an anonymous class object.
+There, qualifiers were simply ignored semantically.
+
+Explicitly qualifying types in base class lists is a parse error now.
+
+This only affects parsing.
+If a `mixin` or `typeof` or an identifier is used, nothing changes.
+If it resolves to a qualified type,
+the qualifier is ignored.
+---
+class C : const(Object) { } // Parse error now
+auto obj = new class const(Object) { }; // Parse error now
+---
+There is no deprecation period.
+The fix is to remove the unnecessary and misleading qualifier from your code.
diff --git a/compiler/src/dmd/parse.d b/compiler/src/dmd/parse.d
index 33e0e5a11310..535095562d8a 100644
--- a/compiler/src/dmd/parse.d
+++ b/compiler/src/dmd/parse.d
@@ -2813,7 +2813,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
                 {
                 case TOK.rightParenthesis:
                     if (storageClass != 0 || udas !is null)
-                        error("basic type expected, not `)`");
+                        error("primary type expected, not `)`");
                     break;
 
                 case TOK.dotDotDot:
@@ -3028,7 +3028,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
             nextToken();
             int alt = 0;
             const typeLoc = token.loc;
-            memtype = parseBasicType();
+            memtype = parsePrimaryType();
             memtype = parseDeclarator(memtype, alt, null);
             checkCstyleTypeSyntax(typeLoc, memtype, alt, null);
         }
@@ -3140,7 +3140,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
                     else
                     {
                         Token* t = &token;
-                        if (isBasicType(&t))
+                        if (isPrimaryType(&t))
                         {
                             error("named enum cannot declare member with type", (*t).toChars());
                             nextToken();
@@ -3541,7 +3541,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
         const typeLoc = token.loc;
 
         AST.Type t;
-        t = parseBasicType();
+        t = parsePrimaryType();
 
         if (pdeclLoc)
             *pdeclLoc = token.loc;
@@ -3553,7 +3553,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
         return t;
     }
 
-    private AST.Type parseBasicType(bool dontLookDotIdents = false)
+    private AST.Type parseBasicType(bool dontLookDotIdents = false, bool parsingPrimaryType = false)
     {
         AST.Type t;
         Loc loc;
@@ -3682,11 +3682,11 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
             {
                 // ident!(template_arguments)
                 auto tempinst = new AST.TemplateInstance(loc, id, parseTemplateArguments());
-                t = parseBasicTypeStartingAt(new AST.TypeInstance(loc, tempinst), dontLookDotIdents);
+                t = parsePrimaryTypeStartingAt(new AST.TypeInstance(loc, tempinst), dontLookDotIdents);
             }
             else
             {
-                t = parseBasicTypeStartingAt(new AST.TypeIdentifier(loc, id), dontLookDotIdents);
+                t = parsePrimaryTypeStartingAt(new AST.TypeIdentifier(loc, id), dontLookDotIdents);
             }
             break;
 
@@ -3702,14 +3702,31 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
 
         case TOK.dot:
             // Leading . as in .foo
-            t = parseBasicTypeStartingAt(new AST.TypeIdentifier(token.loc, Id.empty), dontLookDotIdents);
+            t = parsePrimaryTypeStartingAt(new AST.TypeIdentifier(token.loc, Id.empty), dontLookDotIdents);
             break;
 
         case TOK.typeof_:
             // typeof(expression)
-            t = parseBasicTypeStartingAt(parseTypeof(), dontLookDotIdents);
+            t = parsePrimaryTypeStartingAt(parseTypeof(), dontLookDotIdents);
             break;
 
+        default:
+            immutable char* kind = parsingPrimaryType ? "primary" : "basic";
+            error("%s type expected, not `%s`", kind, token.toChars());
+            if (token.value == TOK.else_)
+                eSink.errorSupplemental(token.loc, "There's no `static else`, use `else` instead.");
+            t = AST.Type.terror;
+            break;
+        }
+        return t;
+    }
+
+    private AST.Type parsePrimaryType(bool dontLookDotIdents = false)
+    {
+        AST.Type t;
+        //printf("parsePrimaryType()\n");
+        switch (token.value)
+        {
         case TOK.vector:
             t = parseVector();
             break;
@@ -3757,20 +3774,17 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
             break;
 
         default:
-            error("basic type expected, not `%s`", token.toChars());
-            if (token.value == TOK.else_)
-                eSink.errorSupplemental(token.loc, "There's no `static else`, use `else` instead.");
-            t = AST.Type.terror;
+            t = parseBasicType(dontLookDotIdents, /+parsingPrimaryType:+/true);
             break;
         }
         return t;
     }
 
-    private AST.Type parseBasicTypeStartingAt(AST.TypeQualified tid, bool dontLookDotIdents)
+    private AST.Type parsePrimaryTypeStartingAt(AST.TypeQualified tid, bool dontLookDotIdents)
     {
         AST.Type maybeArray = null;
         // See https://issues.dlang.org/show_bug.cgi?id=1215
-        // A basic type can look like MyType (typical case), but also:
+        // A primary type can look like MyType (typical case), but also:
         //  MyType.T -> A type
         //  MyType[expr] -> Either a static array of MyType or a type (iif MyType is a Ttuple)
         //  MyType[expr].T -> A type.
@@ -4491,7 +4505,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
                 }
                 else
                 {
-                    ts = parseBasicType();
+                    ts = parsePrimaryType();
                     ts = parseTypeSuffixes(ts);
                 }
             }
@@ -4947,7 +4961,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
                     if (udas)
                         error("user-defined attributes not allowed for `alias` declarations");
 
-                    auto t = parseBasicType();
+                    auto t = parsePrimaryType();
                     t = parseTypeSuffixes(t);
                     if (token.value == TOK.identifier)
                     {
@@ -5092,7 +5106,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
             {
                 // function type (parameters) { statements... }
                 // delegate type (parameters) { statements... }
-                tret = parseBasicType();
+                tret = parsePrimaryType();
                 tret = parseTypeSuffixes(tret); // function return type
             }
 
@@ -7201,7 +7215,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
             break;
         }
 
-        if (!isBasicType(&t))
+        if (!isPrimaryType(&t))
         {
             goto Lisnot;
         }
@@ -7230,10 +7244,10 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
         return false;
     }
 
-    // pt = test token. If found, pt is set to the token after BasicType
-    private bool isBasicType(Token** pt)
+    // pt = test token. If found, pt is set to the token after PrimaryType
+    private bool isPrimaryType(Token** pt)
     {
-        // This code parallels parseBasicType()
+        // This code parallels parsePrimaryType()
         Token* t = *pt;
         switch (t.value)
         {
@@ -7736,7 +7750,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
 
             default:
                 {
-                    if (!isBasicType(&t))
+                    if (!isPrimaryType(&t))
                         return false;
                 L2:
                     int tmp = false;
@@ -8775,7 +8789,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
             {
                 StorageClass stc = parseTypeCtor();
 
-                AST.Type t = parseBasicType();
+                AST.Type t = parsePrimaryType();
                 t = t.addSTC(stc);
 
                 if (stc == 0 && token.value == TOK.dot)
@@ -9543,7 +9557,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
         }
 
         const stc = parseTypeCtor();
-        auto t = parseBasicType(true);
+        auto t = parsePrimaryType(true);
         t = parseTypeSuffixes(t);
         t = t.addSTC(stc);
         if (t.ty == Taarray)
diff --git a/compiler/test/compilable/test1353.d b/compiler/test/compilable/test1353.d
index b724aa818b1e..cb0f6487fb8e 100644
--- a/compiler/test/compilable/test1353.d
+++ b/compiler/test/compilable/test1353.d
@@ -6,9 +6,9 @@ interface D(X) {}
 
 void fun()
 {
-    class T : typeof(new A), .B, const(C), D!int {}
+    class T : typeof(new A), .B, C, D!int {}
     version(none)
     {
-        class U : int, float, __vector(int[3]) {}
+        class U : int, float {}
     }
 }
diff --git a/compiler/test/fail_compilation/b20780.d b/compiler/test/fail_compilation/b20780.d
index ec6917bb58ae..23a657012591 100644
--- a/compiler/test/fail_compilation/b20780.d
+++ b/compiler/test/fail_compilation/b20780.d
@@ -3,7 +3,7 @@ TEST_OUTPUT:
 ---
 fail_compilation/b20780.d(10): Error: `@identifier` or `@(ArgumentList)` expected, not `@)`
 fail_compilation/b20780.d(11): Error: `@identifier` or `@(ArgumentList)` expected, not `@,`
-fail_compilation/b20780.d(11): Error: basic type expected, not `,`
+fail_compilation/b20780.d(11): Error: primary type expected, not `,`
 ---
 */
 
diff --git a/compiler/test/fail_compilation/diag19225.d b/compiler/test/fail_compilation/diag19225.d
index a43a7e10e07a..4b34becb5e4d 100644
--- a/compiler/test/fail_compilation/diag19225.d
+++ b/compiler/test/fail_compilation/diag19225.d
@@ -1,7 +1,7 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/diag19225.d(14): Error: basic type expected, not `else`
+fail_compilation/diag19225.d(14): Error: primary type expected, not `else`
 fail_compilation/diag19225.d(14):        There's no `static else`, use `else` instead.
 fail_compilation/diag19225.d(14): Error: found `else` without a corresponding `if`, `version` or `debug` statement
 fail_compilation/diag19225.d(15): Error: unmatched closing brace
diff --git a/compiler/test/fail_compilation/e15876_3.d b/compiler/test/fail_compilation/e15876_3.d
index 7e9d70913d25..9358004bb840 100644
--- a/compiler/test/fail_compilation/e15876_3.d
+++ b/compiler/test/fail_compilation/e15876_3.d
@@ -2,7 +2,7 @@
 TEST_OUTPUT:
 ---
 fail_compilation/e15876_3.d(28): Error: unexpected `(` in declarator
-fail_compilation/e15876_3.d(28): Error: basic type expected, not `=`
+fail_compilation/e15876_3.d(28): Error: primary type expected, not `=`
 fail_compilation/e15876_3.d(29): Error: found `End of File` when expecting `(`
 fail_compilation/e15876_3.d(29): Error: found `End of File` instead of statement
 fail_compilation/e15876_3.d(29): Error: expression expected, not `End of File`
diff --git a/compiler/test/fail_compilation/e15876_5.d b/compiler/test/fail_compilation/e15876_5.d
index 42183b26bd09..a3b573719c22 100644
--- a/compiler/test/fail_compilation/e15876_5.d
+++ b/compiler/test/fail_compilation/e15876_5.d
@@ -1,7 +1,7 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/e15876_5.d(17): Error: basic type expected, not `End of File`
+fail_compilation/e15876_5.d(17): Error: primary type expected, not `End of File`
 fail_compilation/e15876_5.d(17): Error: semicolon expected to close `alias` declaration, not `End of File`
 fail_compilation/e15876_5.d(17): Error: matching `}` expected following compound statement, not `End of File`
 fail_compilation/e15876_5.d(16):        unmatched `{`
diff --git a/compiler/test/fail_compilation/enum_member.d b/compiler/test/fail_compilation/enum_member.d
index 94c6f9811952..5023d6d845b1 100644
--- a/compiler/test/fail_compilation/enum_member.d
+++ b/compiler/test/fail_compilation/enum_member.d
@@ -1,7 +1,7 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/enum_member.d(14): Error: basic type expected, not `for`
+fail_compilation/enum_member.d(14): Error: primary type expected, not `for`
 fail_compilation/enum_member.d(15): Error: no identifier for declarator `T`
 fail_compilation/enum_member.d(15): Error: found `@` when expecting `,`
 fail_compilation/enum_member.d(22): Error: found `}` when expecting `identifier`
diff --git a/compiler/test/fail_compilation/fail15667.d b/compiler/test/fail_compilation/fail15667.d
index ce4940ffa31b..78ed75fbef43 100644
--- a/compiler/test/fail_compilation/fail15667.d
+++ b/compiler/test/fail_compilation/fail15667.d
@@ -3,7 +3,7 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/imports/a15667.d(16): Error: basic type expected, not `;`
+fail_compilation/imports/a15667.d(16): Error: primary type expected, not `;`
 fail_compilation/imports/a15667.d(19): Error: declaration expected following attribute, not end of file
 ---
 */
diff --git a/compiler/test/fail_compilation/ice11982.d b/compiler/test/fail_compilation/ice11982.d
index f500700f674b..efa69f7f0cfe 100644
--- a/compiler/test/fail_compilation/ice11982.d
+++ b/compiler/test/fail_compilation/ice11982.d
@@ -1,10 +1,10 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/ice11982.d(22): Error: basic type expected, not `scope`
+fail_compilation/ice11982.d(22): Error: primary type expected, not `scope`
 fail_compilation/ice11982.d(22): Error: found `scope` when expecting `;` following expression
 fail_compilation/ice11982.d(22):        expression: `new _error_`
-fail_compilation/ice11982.d(22): Error: basic type expected, not `}`
+fail_compilation/ice11982.d(22): Error: primary type expected, not `}`
 fail_compilation/ice11982.d(22): Error: missing `{ ... }` for function literal
 fail_compilation/ice11982.d(22): Error: C style cast illegal, use `cast(funk)function _error_()
 {
diff --git a/compiler/test/fail_compilation/ice15127.d b/compiler/test/fail_compilation/ice15127.d
index afc6419725ff..98dbcd99089d 100644
--- a/compiler/test/fail_compilation/ice15127.d
+++ b/compiler/test/fail_compilation/ice15127.d
@@ -1,7 +1,7 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/ice15127.d(17): Error: basic type expected, not `struct`
+fail_compilation/ice15127.d(17): Error: primary type expected, not `struct`
 fail_compilation/ice15127.d(17): Error: identifier expected for template value parameter
 fail_compilation/ice15127.d(17): Error: found `struct` when expecting `)`
 fail_compilation/ice15127.d(17): Error: found `ExampleStruct` when expecting `=`
diff --git a/compiler/test/fail_compilation/misc_parser_err_cov1.d b/compiler/test/fail_compilation/misc_parser_err_cov1.d
index 4a8875d6d69c..fcd25b2d5b4c 100644
--- a/compiler/test/fail_compilation/misc_parser_err_cov1.d
+++ b/compiler/test/fail_compilation/misc_parser_err_cov1.d
@@ -2,8 +2,8 @@
 REQUIRED_ARGS: -verrors=0
 TEST_OUTPUT:
 ---
-fail_compilation/misc_parser_err_cov1.d(29): Error: basic type expected, not `)`
-fail_compilation/misc_parser_err_cov1.d(30): Error: basic type expected, not `)`
+fail_compilation/misc_parser_err_cov1.d(29): Error: primary type expected, not `)`
+fail_compilation/misc_parser_err_cov1.d(30): Error: primary type expected, not `)`
 fail_compilation/misc_parser_err_cov1.d(31): Error: `__traits(identifier, args...)` expected
 fail_compilation/misc_parser_err_cov1.d(31): Error: semicolon expected following auto declaration, not `o`
 fail_compilation/misc_parser_err_cov1.d(31): Error: expression expected, not `)`
diff --git a/compiler/test/fail_compilation/qualbaseclass1.d b/compiler/test/fail_compilation/qualbaseclass1.d
new file mode 100644
index 000000000000..675150d2cd2e
--- /dev/null
+++ b/compiler/test/fail_compilation/qualbaseclass1.d
@@ -0,0 +1,12 @@
+/* TEST_OUTPUT:
+---
+fail_compilation\qualbaseclass1.d(101): Error: basic type expected, not `const`
+fail_compilation\qualbaseclass1.d(101): Error: { } expected following `class` declaration
+fail_compilation\qualbaseclass1.d(101): Error: variable name expected after type `const(Object)`, not `{`
+fail_compilation\qualbaseclass1.d(101): Error: declaration expected, not `{`
+---
+ */
+
+#line 100
+
+class C : const(Object) { }
diff --git a/compiler/test/fail_compilation/qualbaseclass2.d b/compiler/test/fail_compilation/qualbaseclass2.d
new file mode 100644
index 000000000000..e9f0fc51439d
--- /dev/null
+++ b/compiler/test/fail_compilation/qualbaseclass2.d
@@ -0,0 +1,15 @@
+/* TEST_OUTPUT:
+---
+fail_compilation\qualbaseclass2.d(103): Error: basic type expected, not `const`
+fail_compilation\qualbaseclass2.d(103): Error: `{ members }` expected for anonymous class
+fail_compilation\qualbaseclass2.d(103): Error: semicolon expected following auto declaration, not `const`
+fail_compilation/qualbaseclass2.d(103): Error: variable name expected after type `const(Object)`, not `{`
+---
+ */
+
+#line 100
+
+void test()
+{
+    auto obj = new class () const(Object) { };
+}
diff --git a/compiler/test/fail_compilation/udaparams.d b/compiler/test/fail_compilation/udaparams.d
index 06f4bd8b67b3..33231943a013 100644
--- a/compiler/test/fail_compilation/udaparams.d
+++ b/compiler/test/fail_compilation/udaparams.d
@@ -18,10 +18,10 @@ fail_compilation/udaparams.d(53): Error: semicolon expected to close `alias` dec
 fail_compilation/udaparams.d(53): Error: declaration expected, not `1`
 fail_compilation/udaparams.d(54): Error: semicolon expected to close `alias` declaration, not `=>`
 fail_compilation/udaparams.d(54): Error: declaration expected, not `1`
-fail_compilation/udaparams.d(57): Error: basic type expected, not `@`
+fail_compilation/udaparams.d(57): Error: primary type expected, not `@`
 fail_compilation/udaparams.d(57): Error: identifier expected for template value parameter
 fail_compilation/udaparams.d(57): Error: found `@` when expecting `)`
-fail_compilation/udaparams.d(57): Error: basic type expected, not `3`
+fail_compilation/udaparams.d(57): Error: primary type expected, not `3`
 fail_compilation/udaparams.d(57): Error: found `3` when expecting `)`
 fail_compilation/udaparams.d(57): Error: semicolon expected following function declaration, not `)`
 fail_compilation/udaparams.d(57): Error: variable name expected after type `T`, not `)`