Fix detection of _Static_assert() in C (#7126)

Correct previous by honoring _Static_assert (introduced in C11) in C.

Author: mptre

lib/checkother.cpp

@@ -2575,9 +2575,19 @@ namespace {
 }
 
 static bool
-isStaticAssert(const Token *tok)
+isStaticAssert(const Settings &settings, const Token *tok)
 {
-    return Token::Match(tok, "_Static_assert|static_assert (");
+    if (tok->isCpp() && settings.standards.cpp >= Standards::CPP11 &&
+        Token::simpleMatch(tok, "static_assert")) {
+        return true;
+    }
+
+    if (tok->isC() && settings.standards.c >= Standards::C11 &&
+        Token::simpleMatch(tok, "_Static_assert")) {
+        return true;
+    }
+
+    return false;
 }
 
 void CheckOther::checkDuplicateExpression()
@@ -2701,12 +2711,12 @@ void CheckOther::checkDuplicateExpression()
                             if (assignment)
                                 selfAssignmentError(tok, tok->astOperand1()->expressionString());
                             else if (!isEnum) {
-                                if (tok->isCpp() && mSettings->standards.cpp >= Standards::CPP11 && tok->str() == "==") {
+                                if (tok->str() == "==") {
                                     const Token* parent = tok->astParent();
                                     while (parent && parent->astParent()) {
                                         parent = parent->astParent();
                                     }
-                                    if (parent && isStaticAssert(parent->previous())) {
+                                    if (parent && parent->previous() && isStaticAssert(*mSettings, parent->previous())) {
                                         continue;
                                     }
                                 }

test/testother.cpp

@@ -6920,7 +6920,7 @@ class TestOther : public TestFixture {
         check("void f() {\n"
               "    enum { Four = 4 };\n"
               "    _Static_assert(Four == 4, \"\");\n"
-              "}");
+              "}", false);
         ASSERT_EQUALS("", errout_str());
 
         check("void f() {\n"