Error map
need typename before dependent name C++: error: need 'typename' before 'T::iterator' because 'T' is a dependent scope
C/C++ · layer 4, Application & API
Centre: this error. First ring: errors it is linked with (8). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (8)
C/C++: error: expected ';' before 'x' — missing semicolon
The compiler reached a token where a statement should have ended — almost always a missing semicolon on the line above.
C++: error: 'x' was not declared in this scope (undeclared identifier)
The compiler met a name it has never seen: it is misspelled, declared later, out of scope, or its header or namespace is missing.
C++: error: no match for 'operator<<' (operand types are 'std::ostream' and 'X')
You used an operator on a type that does not define it — most often printing your own class with `
C++: error: expected primary-expression before ')' token
The parser expected a value or expression and found a token that cannot start one — often a type name passed where a value belong…
C++: error: 'string' does not name a type
Where the compiler expected a type, it found a name it does not know as one — a missing header, namespace, or class declared late…
C++: error: template argument deduction/substitution failed / couldn't deduce template parameter
The compiler could not work out the template arguments from your call — the arguments disagree, the type can't be deduced, or a c…
C/C++: error: stray '\342' in program (smart quotes or invisible characters)
The source file contains a character the compiler does not recognise, typically curly quotes or a non-breaking space pasted from…
C++: error: expected unqualified-id before 'return' / before ')' token
The parser found a token where a name (declaration) was required — often a missing brace, a stray `)`, or a statement placed in a…
Two steps away (12)
Go: declared and not used: x / "fmt" imported and not used
Go refuses to compile code with unused local variables or unused imports.
C/C++: undefined reference to `function' — collect2: error: ld returned 1 exit status
The linker can’t find the definition of a function or variable that was declared and used.
C++: error: 'optional' in namespace 'std' does not name a template type — wrong -std standard
The standard-library feature you used needs a newer C++ standard than the compiler is currently set to.
C: warning: implicit declaration of function 'foo' [-Wimplicit-function-declaration]
In C you called a function the compiler has not seen declared — usually a missing `#include`. Newer compilers treat it as an erro…
C++: error: no matching function for call to 'f(int, const char*)'
No overload of the function accepts the arguments you passed — wrong count, wrong types, or a missing conversion.
C++: error: call of overloaded 'f(int)' is ambiguous
Two or more overloads fit equally well, so the compiler refuses to guess which function you meant.
C++: error: cannot declare variable 'x' to be of abstract type 'Shape' (pure virtual functions)
You tried to create an object of a class that still has pure virtual functions; only a derived class that overrides all of them c…
Rust: error[E0308]: mismatched types — expected `X`, found `Y`
A value’s type doesn’t match what the context expects — common with &str vs String, Option/Result vs plain values, and integer ty…
C++: error: invalid conversion from 'const char*' to 'char*' [-fpermissive]
C++ forbids silently dropping `const` or converting between unrelated pointer types — typically a string literal assigned to `cha…
C++: error: invalid use of incomplete type 'class X' — forward declaration only
You used a class that has only been forward-declared (so its size and members are unknown) where the full definition is required.
C++: error: narrowing conversion of 'x' from 'int' to 'char' inside { } [-Wnarrowing]
Brace initialisation `{}` refuses conversions that can lose data, such as `double` to `int` or a runtime `int` to `char`.
C++: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
You compared a string literal or pointer with a character or integer — typically `ch == "y"` instead of `ch == 'y'`.
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