Improve unreachableCodeError message (#4559)

* Update templatesimplifier.cpp

* Add tests

* Improve unreachableCodeError message

* Update templatesimplifier.cpp

* Add tests

* Improve unreachableCodeError message

* Revert "Update templatesimplifier.cpp"

This reverts commit 3fd152ed4063772a5f162bd985c3d91bcc65eb55.

* Revert "Add tests"

This reverts commit e760ab51e66a0a2c3a0250caf4cf3b745db44d10.

lib/checkother.cpp

@@ -825,7 +825,7 @@ void CheckOther::checkUnreachableCode()
                         secondBreak = silencedWarning;
 
                     if (!labelInFollowingLoop && !silencedCompilerWarningOnly)
-                        unreachableCodeError(secondBreak, inconclusive);
+                        unreachableCodeError(secondBreak, tok, inconclusive);
                     tok = Token::findmatch(secondBreak, "[}:]");
                 } else if (secondBreak->scope() && secondBreak->scope()->isLoopScope() && secondBreak->str() == "}" && tok->str() == "continue") {
                     redundantContinueError(tok);
@@ -849,10 +849,18 @@ void CheckOther::duplicateBreakError(const Token *tok, bool inconclusive)
                 "The second statement can never be executed, and so should be removed.", CWE561, inconclusive ? Certainty::inconclusive : Certainty::normal);
 }
 
-void CheckOther::unreachableCodeError(const Token *tok, bool inconclusive)
+void CheckOther::unreachableCodeError(const Token *tok, const Token* noreturn, bool inconclusive)
 {
+    std::string msg = "Statements following ";
+    if (noreturn && noreturn->function())
+        msg += "noreturn function '" + noreturn->str() + "()'";
+    else if (noreturn && noreturn->isKeyword())
+        msg += "'" + noreturn->str() + "'";
+    else
+        msg += "return, break, continue, goto or throw";
+    msg += " will never be executed.";
     reportError(tok, Severity::style, "unreachableCode",
-                "Statements following return, break, continue, goto or throw will never be executed.", CWE561, inconclusive ? Certainty::inconclusive : Certainty::normal);
+                msg, CWE561, inconclusive ? Certainty::inconclusive : Certainty::normal);
 }
 
 void CheckOther::redundantContinueError(const Token *tok)

lib/checkother.h

@@ -259,7 +259,7 @@ private:
     void duplicateValueTernaryError(const Token *tok);
     void duplicateExpressionTernaryError(const Token *tok, ErrorPath errors);
     void duplicateBreakError(const Token *tok, bool inconclusive);
-    void unreachableCodeError(const Token* tok, bool inconclusive);
+    void unreachableCodeError(const Token* tok, const Token* noreturn, bool inconclusive);
     void redundantContinueError(const Token* tok);
     void unsignedLessThanZeroError(const Token *tok, const ValueFlow::Value *v, const std::string &varname);
     void pointerLessThanZeroError(const Token *tok, const ValueFlow::Value *v);
@@ -327,7 +327,7 @@ private:
         c.duplicateValueTernaryError(nullptr);
         c.duplicateExpressionTernaryError(nullptr, errorPath);
         c.duplicateBreakError(nullptr,  false);
-        c.unreachableCodeError(nullptr,  false);
+        c.unreachableCodeError(nullptr, nullptr,  false);
         c.unsignedLessThanZeroError(nullptr, nullptr, "varname");
         c.unsignedPositiveError(nullptr, nullptr, "varname");
         c.pointerLessThanZeroError(nullptr, nullptr);

test/testother.cpp

@@ -4291,7 +4291,7 @@ private:
               "    return 0;\n"
               "    foo();\n"
               "}", nullptr, false, false, false);
-        ASSERT_EQUALS("[test.cpp:3]: (style) Statements following return, break, continue, goto or throw will never be executed.\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:3]: (style) Statements following 'return' will never be executed.\n", errout.str());
 
         check("int foo(int unused) {\n"
               "    return 0;\n"
@@ -4312,7 +4312,7 @@ private:
               "    (void)unused2;\n"
               "    foo();\n"
               "}", nullptr, false, false, false);
-        ASSERT_EQUALS("[test.cpp:5]: (style) Statements following return, break, continue, goto or throw will never be executed.\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:5]: (style) Statements following 'return' will never be executed.\n", errout.str());
 
         check("int foo() {\n"
               "    if(bar)\n"
@@ -4349,7 +4349,7 @@ private:
               "    return 0;\n"
               "    j=2;\n"
               "}", nullptr, false, false, false);
-        ASSERT_EQUALS("[test.cpp:7]: (style) Statements following return, break, continue, goto or throw will never be executed.\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:7]: (style) Statements following 'return' will never be executed.\n", errout.str());
 
         check("int foo() {\n"
               "    return 0;\n"
@@ -4496,6 +4496,13 @@ private:
                "    return INB(port_1);\n"
                "}\n", "test.c");
         ASSERT_EQUALS("", errout.str());
+
+        check("[[noreturn]] void n();\n"
+              "void f() {\n"
+              "    n();\n"
+              "    g();\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:4]: (style) Statements following noreturn function 'n()' will never be executed.\n", errout.str());
     }
 
     void redundantContinue() {