Fix cmake header (#1491)

* Fixed guessing of CMake by header.

* Version number can have multiple digits.
* Tabs are handled as white space.
* Trailing comments are ignored.

* Cleaned up regex to detect CMake header.

2 files changed, 35 insertions, 1 deletions

diff --git a/pygments/lexers/make.py b/pygments/lexers/make.py
index 121db1c2..5f65afcc 100644
--- a/pygments/lexers/make.py
+++ b/pygments/lexers/make.py
@@ -196,7 +196,12 @@ class CMakeLexer(RegexLexer):
     }
 
     def analyse_text(text):
-        exp = r'^ *CMAKE_MINIMUM_REQUIRED *\( *VERSION *\d(\.\d)* *( FATAL_ERROR)? *\) *$'
+        exp = (
+            r'^[ \t]*CMAKE_MINIMUM_REQUIRED[ \t]*'
+            r'\([ \t]*VERSION[ \t]*\d+(\.\d+)*[ \t]*'
+            r'([ \t]FATAL_ERROR)?[ \t]*\)[ \t]*'
+            r'(#[^\n]*)?$'
+       )
         if re.search(exp, text, flags=re.MULTILINE | re.IGNORECASE):
             return 0.8
         return 0.0
diff --git a/tests/test_make.py b/tests/test_make.py
new file mode 100644
index 00000000..b311850c
--- /dev/null
+++ b/tests/test_make.py
@@ -0,0 +1,29 @@
+# -*- coding: utf-8 -*-
+"""
+    CMake Tests
+    ~~~~~~~~~~~
+
+    :copyright: Copyright 2006-2020 by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from pygments.lexers import CMakeLexer, guess_lexer
+
+
+def test_guess_cmake_lexer_from_header():
+    headers = [
+        "CMAKE_MINIMUM_REQUIRED(VERSION 2.6 FATAL_ERROR)",
+        "cmake_minimum_required(version 3.13)  # CMake version check",
+        " CMAKE_MINIMUM_REQUIRED\t( VERSION 2.6 FATAL_ERROR ) ",
+    ]
+    for header in headers:
+        code = '\n'.join([
+            header,
+            'project(example)',
+            'set(CMAKE_CXX_STANDARD 14)',
+            'set(SOURCE_FILES main.cpp)',
+            'add_executable(example ${SOURCE_FILES})',
+        ])
+        lexer = guess_lexer(code)
+        assert isinstance(lexer, CMakeLexer), \
+            "header must be detected as CMake: %r" % header