From de83fc785fd9b3518059a37c2730b70f095409a7 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Mon, 5 Aug 2024 19:29:29 +0200
Subject: [PATCH] Fix #12987 false negative: knownConditionTrueFalse with
 std::string (regression) (#6661)

---
 lib/valueflow.cpp      | 3 ++-
 test/testvalueflow.cpp | 7 +++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 11999c79bb6..72c3fbf588c 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -6909,7 +6909,8 @@ static std::vector<ValueFlow::Value> getContainerSizeFromConstructorArgs(const s
         }
     } else if (container->stdStringLike) {
         if (astIsPointer(args[0])) {
-            // TODO: Try to read size of string literal { "abc" }
+            if (args.size() == 1 && args[0]->tokType() == Token::Type::eString)
+                return {makeContainerSizeValue(Token::getStrLength(args[0]), known)};
             if (args.size() == 2 && astIsIntegral(args[1], false)) // { char*, count }
                 return {makeContainerSizeValue(args[1], known)};
         } else if (astIsContainer(args[0])) {
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index 84b3a1f13bd..f1250b87ab8 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -6919,6 +6919,13 @@ class TestValueFlow : public TestFixture {
                "    return x;\n"
                "}\n";
         ASSERT_EQUALS(false, testValueOfXKnown(code, 9U, 1));
+
+        code = "int f() {\n" // #12987
+               "    std::string s{\"0\"};\n"
+               "    auto x = s.size();\n"
+               "    return x;\n"
+               "}\n";
+        ASSERT_EQUALS(true, testValueOfXKnown(code, 4U, 1));
     }
 
     void valueFlowContainerElement()