Eigen Compiler Suite

A small adjustment to the makefile was needed from line 153 to complete the build on Windows and MSYS2 :

+    else ifdef MSYSTEM
+        environment := windows.cpp
+        
+        ifdef CommonProgramFiles(x86)
+            hostenvironments := win32 win64
+        else
+            hostenvironments := dos win32
+        endif
+
+        ifndef toolchain
+            toolchain := clang
+        endif
    else
        environment := $(error unknown posix environment)
    endif

My own tests run fine.

When running the ECS tests it runs fine until:

makefile:1357: update target 'tests/docprintcheck' due to: target does not exist
cd tests/ && ../utilities/regtest "/home/rute/ecs/tools/docprint docprintcheck.doc > docprintcheck.out && /home/rute/ecs/tools/doccheck docprintcheck.out" docprintcheck.doc docprintcheck.res doccheck.tst && touch docprintcheck

Overview:
command line: C:/msys64/home/rute/ecs/tools/docprint docprintcheck.doc > docprintcheck.out && /home/rute/ecs/tools/doccheck docprintcheck.out
temporary:    docprintcheck.doc (C:\msys64\tmp\regtest-3928400913)
test results: docprintcheck.res (0)
test suites:  doccheck.tst (1)

Test suite 'doccheck.tst':
The system cannot find the path specified.
positive test 'empty document' in line 19 failed with status 1
The system cannot find the path specified.
positive test 'article missing text' in line 23 failed with status 1
The system cannot find the path specified.
positive test 'article with text' in line 27 failed with status 1
The system cannot find the path specified.
The system cannot find the path specified.
The system cannot find the path specified.
positive test 'articles with valid nesting levels' in line 40 failed with status 1
The system cannot find the path specified.
positive test 'heading missing text' in line 52 failed with status 1
The system cannot find the path specified.
positive test 'heading with text' in line 56 failed with status 1
The system cannot find the path specified.
The system cannot find the path specified.
The system cannot find the path specified.
positive test 'headings with valid nesting levels' in line 69 failed with status 1
The system cannot find the path specified.
positive test 'numbered list item missing text' in line 81 failed with status 1
The system cannot find the path specified.
positive test 'numbered list item with text' in line 85 failed with status 1
The system cannot find the path specified.
The system cannot find the path specified.
The system cannot find the path specified.
positive test 'numbered list items with valid nesting levels' in line 98 failed with status 1
The system cannot find the path specified.
positive test 'list item missing text' in line 110 failed with status 1
The system cannot find the path specified.
positive test 'list item with text' in line 114 failed with status 1
The system cannot find the path specified.
The system cannot find the path specified.
The system cannot find the path specified.
positive test 'list items with valid nesting levels' in line 127 failed with status 1
The system cannot find the path specified.
positive test 'label with single name' in line 151 failed with status 1
The system cannot find the path specified.
The system cannot find the path specified.
The system cannot find the path specified.
positive test 'link with single name' in line 182 failed with status 1
The system cannot find the path specified.
The system cannot find the path specified.
positive test 'link before label' in line 196 failed with status 1
The system cannot find the path specified.
positive test 'link after label' in line 200 failed with status 1
The system cannot find the path specified.
positive test 'link before label in different articles' in line 204 failed with status 1
The system cannot find the path specified.
positive test 'link after label in different articles' in line 209 failed with status 1

Summary:
number of tests: 38 (+38)
succeeded tests: 19
failed tests:    19
make: *** [makefile:1357: tests/docprintcheck] Error 1

It seems the file docprintcheck.doc is missing.