From 17e776861e331c0238a77a66009cf975323240d9 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Tue, 28 Feb 2023 15:05:45 +0100
Subject: [PATCH] Get type from auto with index operator (#4826)

---
 lib/token.cpp               |  6 ++++++
 test/testfunctions.cpp      | 12 ++++++++++++
 test/testsymboldatabase.cpp | 14 ++++++++++++++
 3 files changed, 32 insertions(+)

diff --git a/lib/token.cpp b/lib/token.cpp
index d2fe45e4a..f4881ad59 100644
--- a/lib/token.cpp
+++ b/lib/token.cpp
@@ -2265,6 +2265,12 @@ std::pair<const Token*, const Token*> Token::typeDecl(const Token* tok, bool poi
             if (Token::simpleMatch(tok2, "=") && Token::Match(tok2->astOperand2(), "!!=") && tok != tok2->astOperand2()) {
                 tok2 = tok2->astOperand2();
 
+                if (Token::simpleMatch(tok2, "[") && tok2->astOperand1()) {
+                    const ValueType* vt = tok2->astOperand1()->valueType();
+                    if (vt && vt->containerTypeToken)
+                        return { vt->containerTypeToken, vt->containerTypeToken->linkAt(-1) };
+                }
+
                 const Token* varTok = tok2; // try to find a variable
                 if (Token::Match(varTok, ":: %name%"))
                     varTok = varTok->next();
diff --git a/test/testfunctions.cpp b/test/testfunctions.cpp
index ba9b628fa..9cccc61fd 100644
--- a/test/testfunctions.cpp
+++ b/test/testfunctions.cpp
@@ -1986,6 +1986,18 @@ private:
               "}\n");
         ASSERT_EQUALS("", errout.str());
 
+        check("void f(std::vector<std::unordered_map<int, std::unordered_set<int>>>& v, int i, int j) {\n"
+              "    auto& s = v[i][j];\n"
+              "    s.insert(0);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
+        check("int f(const std::vector<std::string>& v, int i, char c) {\n"
+              "    const auto& s = v[i];\n"
+              "    return s.find(c);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
         settings = settings_old;
     }
 
diff --git a/test/testsymboldatabase.cpp b/test/testsymboldatabase.cpp
index 72d5aa75c..805a587bd 100644
--- a/test/testsymboldatabase.cpp
+++ b/test/testsymboldatabase.cpp
@@ -481,6 +481,7 @@ private:
 
         TEST_CASE(valueType1);
         TEST_CASE(valueType2);
+        TEST_CASE(valueType3);
         TEST_CASE(valueTypeThis);
 
         TEST_CASE(variadic1); // #7453
@@ -8109,6 +8110,19 @@ private:
         }
     }
 
+    void valueType3() {
+        GET_SYMBOL_DB("void f(std::vector<std::unordered_map<int, std::unordered_set<int>>>& v, int i, int j) {\n"
+                      "    auto& s = v[i][j];\n"
+                      "    s.insert(0);\n"
+                      "}\n");
+        ASSERT_EQUALS("", errout.str());
+
+        const Token* tok = tokenizer.tokens();
+        tok = Token::findsimplematch(tok, "s .");
+        ASSERT(tok && tok->valueType());
+        ASSERT_EQUALS("container(std :: set|unordered_set <)", tok->valueType()->str());
+    }
+
     void valueTypeThis() {
         ASSERT_EQUALS("C *", typeOf("class C { C() { *this = 0; } };", "this"));
         ASSERT_EQUALS("const C *", typeOf("class C { void foo() const; }; void C::foo() const { *this = 0; }", "this"));