Deprecate string literals as (static) assert conditions (#15860)

* Deprecate string literals as assert conditions

Fix Issue 14387 - Disallow string literals as assert conditions

* Avoid running expression semantic, only deprecate literals

Ignore enum strings.

* Fix runnable test

changelog/dmd.assert-string.dd

@@ -0,0 +1,18 @@
+A string literal as an assert condition is deprecated
+
+Boolean evaluation of a string literal could happen unintentionally
+e.g. when an `assert(0, "message")` was meant and the `0` was missing.
+
+```d
+assert("unexpected runtime condition");
+static assert("unhandled case for `", T, "`");
+```
+
+The 2 asserts would silently always have no effect.
+Now these cases will be detected with deprecation messages.
+If the original behaviour was actually intended, use `expr !is null` instead:
+
+```d
+assert("" !is null);
+static assert("" !is null);
+```

compiler/src/dmd/expressionsem.d

@@ -7592,6 +7592,13 @@ private extern (C++) final class ExpressionSemanticVisitor : Visitor
         {
             printf("AssertExp::semantic('%s')\n", exp.toChars());
         }
+        if (auto e = exp.e1.isStringExp())
+        {
+            // deprecated in 2.107
+            deprecation(e.loc, "assert condition cannot be a string literal");
+            deprecationSupplemental(e.loc, "If intentional, use `%s !is null` instead to preserve behaviour",
+                e.toChars());
+        }
 
         const generateMsg = !exp.msg &&
                             sc.needsCodegen() && // let ctfe interpreter handle the error message

compiler/src/dmd/semantic2.d

@@ -93,6 +93,13 @@ private extern(C++) final class Semantic2Visitor : Visitor
     override void visit(StaticAssert sa)
     {
         //printf("StaticAssert::semantic2() %s\n", sa.toChars());
+        if (const e = sa.exp.isStringExp())
+        {
+            // deprecated in 2.107
+            deprecation(e.loc, "static assert condition cannot be a string literal");
+            deprecationSupplemental(e.loc, "If intentional, use `%s !is null` instead to preserve behaviour",
+                e.toChars());
+        }
         auto sds = new ScopeDsymbol();
         sc = sc.push(sds);
         sc.tinst = null;

compiler/test/fail_compilation/array_bool.d

@@ -0,0 +1,22 @@
+/*
+REQUIRED_ARGS: -de
+TEST_OUTPUT:
+---
+fail_compilation/array_bool.d(13): Deprecation: assert condition cannot be a string literal
+fail_compilation/array_bool.d(13):        If intentional, use `"foo" !is null` instead to preserve behaviour
+fail_compilation/array_bool.d(14): Deprecation: static assert condition cannot be a string literal
+fail_compilation/array_bool.d(14):        If intentional, use `"foo" !is null` instead to preserve behaviour
+---
+*/
+void main()
+{
+    assert("foo");
+    static assert("foo");
+
+    assert("foo".ptr); // OK
+    static assert("foo".ptr); // OK
+
+    enum e = "bar";
+    static assert(e); // OK
+    assert(e); // OK
+}

compiler/test/runnable/testpdb.d

@@ -1087,7 +1087,7 @@ bool openDebugInfo(IDiaDataSource* source, IDiaSession* session, IDiaSymbol* glo
 {
     wchar[MAX_PATH] exepath;
     DWORD len = GetModuleFileNameW(null, exepath.ptr, MAX_PATH);
-    len < MAX_PATH || assert("executable path too long");
+    len < MAX_PATH || assert(false, "executable path too long");
 
     HRESULT hr = CoInitialize(NULL);