1031892 bytes / 9 bytes = ratio 114654.666667

Compiler g++-11, with -std=c++20 flag

p<p<p<p<p

produces 1031892 bytes, or 21056 lines of error.

first 20 lines look like this:

test.cpp:1:9: error: ‘p’ was not declared in this scope    1 | p<p<p<p<p      |         ^test.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:7: error: ‘p’ was not declared in this scope    1 | p<p<p<p<p      |       ^test.cpp:1:9: error: ‘p’ was not declared in this scope    1 | p<p<p<p<p      |         ^test.cpp:1:9: error: ‘p’ was not declared in this scope

and last 20 lines:

      |         ^test.cpp:1:5: error: ‘p’ was not declared in this scope    1 | p<p<p<p<p      |     ^test.cpp:1:9: error: ‘p’ was not declared in this scope    1 | p<p<p<p<p      |         ^test.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:9: error: ‘p’ was not declared in this scopetest.cpp:1:7: error: ‘p’ was not declared in this scope    1 | p<p<p<p<p      |       ^test.cpp:1:9: error: ‘p’ was not declared in this scope    1 | p<p<p<p<p      |         ^test.cpp:1:1: error: ‘p’ does not name a type    1 | p<p<p<p<p      | ^

And my compiler version:

$ g++-11 --versiong++-11 (Ubuntu 11.1.0-1ubuntu1~18.04.1) 11.1.0Copyright (C) 2021 Free Software Foundation, Inc.This is free software; see the source for copying conditions.  There is NOwarranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

What if I add more "<p" ?

• 1 byte -> 70 bytes error, ratio = 70

  $ echo 'p'> test.cpp; g++-11 test.cpp -o test -std=c++20 2>&1 | wc -c70

• 3 byte -> 636 bytes error, ratio = 212

  $ echo 'p<p'> test.cpp; g++-11 test.cpp -o test -std=c++20 2>&1 | wc -c636

• 5 byte -> 7608 bytes error, ratio = 1521.6

  $ echo 'p<p<p'> test.cpp; g++-11 test.cpp -o test -std=c++20 2>&1 | wc -c7608

• 7 byte -> 88884 bytes error, ratio = 12697.7142857

  $ echo 'p<p<p<p'> test.cpp; g++-11 test.cpp -o test -std=c++20 2>&1 | wc -c88884

• 9 byte -> 1031892 bytes error, ratio = 114654.666667

  $ echo 'p<p<p<p<p'> test.cpp; g++-11 test.cpp -o test -std=c++20 2>&1 | wc -c1031892

• 11 byte -> 12132840 bytes error, ratio = 1102985.45455

  $ echo 'p<p<p<p<p<p'> test.cpp; g++-11 test.cpp -o test -std=c++20 2>&1 | wc -c12132840

• ...and latter take too much time to evaluate.