CMP0186

Regular expressions match ^ at most once in repeated searches.

This policy affects commands that perform multiple regular expression searches:

• string(REGEX MATCHALL)
• string(REGEX REPLACE)
• list(TRANSFORM REPLACE)

and the generator expression $<LIST:TRANSFORM,list,REPLACE>.

CMake 4.0 and below match the ^ anchor at the start of every successive search, leading to multiple matches:

string(REGEX REPLACE "^a" "b" result "aaaa") # result="bbbb"
string(REGEX MATCHALL "^a" result "aaaa")    # result="a;a;a;a"

CMake 4.1 and above prefer to match the ^ anchor at most once, at the start of the input string:

string(REGEX REPLACE "^a" "b" result "aaaa") # result="baaa"
string(REGEX MATCHALL "^a" result "aaaa")    # result="a"

This policy provides compatibility for projects that have not been updated.

The OLD behavior for this policy is to match ^ multiple times, at the start of each search. The NEW behavior for this policy is to match ^ at most once, at the start of the input string.

This policy was introduced in CMake version 4.1. It may be set by cmake_policy() or cmake_minimum_required(). If it is not set, CMake does not warn, and uses OLD behavior.