My understanding is that the state of semantic IDE features for C++ was pretty miserable until CLion and clangd came along.
That is, sure, there were a whole lot of “literally” IDEs — gui wrappers around editor/build system/debugger/compiler combos. In the post, when I say IDE, I focus on “refactoring rubicon” connotation of the term, not on the literal meaning (https://martinfowler.com/articles/refactoringRubicon.html).
Here is the documentation to cadillac, https://dreamsongs.com/Cadillac.html, and the respective demo of their XEmacs based environment from 1993.
https://www.youtube.com/watch?v=pQQTScuApWk
Refactoring is one feature of IDEs, not the whole package.
Still, here is your refactoring rubicon in Visual Age for C++ (1999), http://www.edm2.com/index.php/VisualAge_C%2B%2B_4.0_Review
https://www.developer.com/java/suns-forte-developer-7-simpli...
Still available under Oracle, now rebranded as Oracle Solaris Studio.
https://docs.oracle.com/cd/E24457_01/html/E21989/gkofj.html#...
Example, these blog posts from 2009 showing that KDevelop already had semantic highlighting, smart auto-completion, quick fixes and whatnot https://zwabel.wordpress.com/
KDevelop had its own C++ parser at the time, and it was quite good. Same for QtCreator. They both moved to use libclang much later.